Nozzle plate and its manufacturing method

【0001】

[Technical field to which the invention belongs]

The present invention relates to a nozzle plate used for a fluid discharge head that discharges a fluid such as ink. More specifically, the present invention is an electrostatic suction type fluid discharge device that discharges a fluid onto an object by charging the fluid and electrostatically sucking the fluid. Regarding the nozzle plate used for.

【0002】

[Conventional technology]

In general, there are various fluid jet methods for ejecting a fluid such as ink onto an object (recording medium). Here, an inkjet method using ink as a fluid will be described.

【0003】

As on-demand type inkjet methods, a piezo method using a piezoelectric phenomenon, a thermal method using an ink film boiling phenomenon, an electrostatic suction method using an electrostatic phenomenon, etc. have been developed. The demand for the inkjet method is increasing. In order to realize high-resolution inkjet recording, it is indispensable to miniaturize the ejected ink droplets.

【0004】

Here, the behavior until the ink droplets ejected from the nozzle land on the recording medium is ρink (4/3 π d.³) Dv / dt = --Cd (1/2 ρair v²) (Π d²/ 4) It can be expressed by the equation of motion (Equation (1)) shown in (1).

【0005】

The above ρink is the volume density of the ink, v is the droplet velocity, Cd is the drag coefficient, ρair is the density of air, d is the ink droplet radius, and Cd is Cd = 24 / Re · (1 + 3/16 · (1 + 3/16 ·) Re^0.62) It can be expressed by Eq. (2) shown in (2).

【0006】

The above Re is the Reynolds number, and η is the viscosity of the air, and Re = 2 d ρink v / η By equation (3) shown in (3) Can be represented.

【0007】

The influence of the droplet radius on the kinetic energy of the ink droplet on the left side of the above equation (1) is larger than the influence of the droplet radius on the viscous resistance of air. Therefore, in the case of the same velocity, the smaller the droplet is, the faster the droplet velocity is decelerated, and the recording medium cannot be reached at a predetermined distance, or even if the droplet is reached, the landing accuracy becomes poor.

【0008】

To prevent this, it is necessary to increase the initial ejection speed of the droplet, that is, to increase the ejection energy per unit volume.

【0009】

However, the conventional piezo type and thermal type inkjet heads have the following problems when the ejection droplets are miniaturized, that is, the ejection energy per unit volume of the ejection droplets is increased, and the ejection droplet amount is 1 pl. Below, that is, it was particularly difficult to reduce the diameter of the droplet (hereinafter referred to as the droplet diameter) to φ10 μm or less.

【0010】

Problem 1: The discharge energy of the piezo type inkjet head is related to the displacement amount and the generated pressure of the driven piezoelectric element. The displacement amount of this piezoelectric element is closely related to the ink ejection amount, that is, the ink droplet size, and in order to reduce the droplet size, the displacement amount must also be reduced, and the ejection energy per unit volume of the ejected droplets. It is difficult to improve.

【0011】

Problem 2: Since the thermal inkjet head uses the phenomenon of ink film boiling, the pressure at the time of bubble formation has a physical limit, and the ejection energy is almost determined by the area of the heating element. The area of this heating element is substantially proportional to the volume of generated bubbles, that is, the amount of ink ejected. Therefore, if the ink droplet size is reduced, the volume of generated bubbles is reduced and the ejection energy is reduced, so that it is difficult to improve the ejection energy per unit volume of the ink droplets.

【0012】

Problem 3: Since the driving amount of the driving (heating) element is closely related to the ejection amount in both the piezo method and the thermal method, it is very difficult to suppress the variation, especially when ejecting a minute droplet size.

【0013】

Therefore, as a method for solving each of the above problems, a method for ejecting fine droplets by an electrostatic suction method has been developed.

【0014】

In the electrostatic suction method, the equation of motion of the ink droplets ejected from the nozzle is expressed by the following equation (4).

【0015】

ρink (4/3 π d³) Dv / dt = q E- Cd (1/2 ρair v²) (Π d²/ 4) ... (4) Here, q is the charge amount of the droplet and E is the electric field strength of the surroundings.

【0016】

From the above equation (4), in the electrostatic suction method, the ejected droplets receive electrostatic force during flight in addition to the ejection energy, so that the ejection energy per unit volume can be reduced, and the ejection energy of minute droplets can be reduced. It can be applied to discharge.

【0017】

As such an electrostatic suction type inkjet device (hereinafter, referred to as an electrostatic suction type inkjet device), for example, Patent Document 1 discloses an inkjet device provided with an electrode for applying a voltage inside the nozzle. .. Further, Patent Document 2 discloses an inkjet device in which a nozzle is used as a slit and a needle electrode protruding from the nozzle is provided to eject ink containing fine particles.

【0018】

The inkjet device disclosed in Patent Document 1 will be described below with reference to FIG. FIG. 17 is a schematic cross-sectional view of the inkjet device.

【0019】

In the figure, 101 is an ink injection chamber, 102 is ink, 103 is an ink chamber, 104 is a nozzle hole, 105 is an ink tank, 106 is an ink supply path, 107 is a rotating roller, 108 is a recording medium, and 110 is a control element unit. 111 indicates a process control unit.

【0020】

Further, 114 is an electrode portion for applying an electrostatic field arranged on the ink chamber 103 side of the ink injection chamber 101, 115 is a counter electrode portion which is a metal drum installed on the rotating roller 107, and 116 is a counter electrode portion 115. It is a bias power supply unit that applies a negative voltage of 1,000 V. Reference numeral 117 denotes a high-voltage power supply unit that supplies a high voltage of several hundred volts to the electrode unit 114 for applying an electrostatic field, and 118 is a grounding unit.

【0021】

Here, between the electrostatic field application electrode section 114 and the counter electrode section 115, the bias power supply section 116 having a negative voltage of several thousand V and the high voltage power supply section 117 having a voltage of several hundred V applied to the counter electrode section 115. A superposed electric field is formed by superimposing the high voltage voltage, and the ejection of the ink 102 from the nozzle hole 104 is controlled by this superposed electric field.

【0022】

Reference numeral 119 is a convex meniscus formed in the nozzle hole 104 by a bias voltage of several thousand V applied to the counter electrode portion 115.

【0023】

The operation of the electrostatic suction type inkjet device configured as described above will be described below.

【0024】

First, the ink 102 is transferred to the nozzle hole 104 for ejecting the ink 102 through the ink supply path 106 due to the capillary phenomenon. At this time, the counter electrode portion 115 on which the recording medium 108 is mounted is arranged so as to face the nozzle hole 104.

【0025】

In the ink 102 that has reached the nozzle hole 104, a convex ink meniscus 119 is formed by a bias voltage of several thousand V applied to the counter electrode portion 115. By applying a signal voltage from the high-voltage power supply unit 117 of several hundred volts to the electrode unit 114 for applying an electrostatic field arranged in the ink chamber 103, the voltage from the bias power supply unit 116 applied to the counter electrode unit 115 can be obtained. The ink 102 is superposed, and the ink 102 is ejected to the recording medium 108 by the superposed electric field to form a printed image.

【0026】

The behavior of the meniscus up to the flight of droplets in the inkjet device disclosed in Patent Document 1 will be described below with reference to FIGS. 18 (a) to 18 (c).

【0027】

Before applying the drive voltage, as shown in Fig. 18 (a), a raised meniscus 119a is formed on the ink surface due to the balance between the electrostatic force due to the bias voltage applied to the ink and the surface tension of the ink. It has become.

【0028】

When a drive voltage is applied in the above state, as shown in FIG. 18 (b), in the meniscus 119b, the electric charge generated on the liquid surface begins to move toward the center of the swelling of the liquid surface, thereby causing the center of the swelling of the liquid surface to move. A raised meniscus 119b is formed.

【0029】

After that, when the driving voltage is continuously applied, as shown in FIG. 18 (c), the electric charge generated on the liquid surface is further concentrated in the center to form a crescent-shaped meniscus 119c called a tailor cone, and the tailor is formed. When the electrostatic force due to the amount of electric charge concentrated on the top of the cone exceeds the surface tension of the ink, the droplets are separated and ejected.

【0030】

Next, the inkjet apparatus disclosed in Patent Document 2 will be described below with reference to FIG. FIG. 19 is a schematic configuration diagram of the inkjet device.

【0031】

As shown in the figure, inside the holding member of the inkjet device, a line-type recording head 211 formed of a low dielectric material (acrylic resin, ceramics, etc.) as an inkjet head, and ink ejection holes of the recording head 211. Opposite electrodes 210 made of metal or high dielectric arranged so as to face each other, ink tank 212 for storing ink in which charged pigment particles are dispersed in a non-conductive ink medium, ink tank 212 and recording head 211. An ink circulation system (pumps 214a, 214b, pipes 215a, 215b) that circulates ink between the two, and a pulse that applies a pulse voltage to each discharge electrode 211a to draw ink droplets that form one pixel of the recorded image. A voltage generator 213, a drive circuit (not shown) that controls the pulse voltage generator 213 according to image data, and a recording medium that allows the recording medium 230 to pass through a gap provided between the recording head 211 and the counter electrode 210. It houses a transport mechanism (not shown), a controller that controls the entire device (not shown), and the like.

【0032】

The ink circulation system is composed of two pipes 215a / 215b connecting the recording head 211 and the ink tank 212, and two pumps 214a / 214b driven by the control of the controller.

【0033】

The ink circulation system is divided into an ink supply system for supplying ink to the recording head 211 and an ink recovery system for collecting ink from the recording head 211.

【0034】

In the ink supply system, ink is sucked up from the ink tank 212 by the pump 214a and pumped to the ink supply section of the recording head 211 via the pipe 215a. On the other hand, in the ink recovery system, ink is sucked by the pump 215b from the ink recovery section of the recording head 211, and the ink is forcibly recovered to the ink tank 212 via the pipe 215b.

【0035】

Further, as shown in FIG. 20, the recording head 211 has an ink supply unit 220a that spreads the ink sent from the ink supply system pipe 215a to the line width, and an ink flow that guides the ink from the ink supply unit 220a into a chevron shape. Slit-shaped ink ejection with an appropriate width (about 0.2 mm) that opens the top of the ink recovery unit 220b and ink flow path 221 that connects the path 221, the ink flow path 221 and the ink recovery system pipe 215b to the opposite electrode 210 side. Hole 222, a plurality of ejection electrodes 211a arranged in the ink ejection holes 222 at a predetermined pitch (about 0.2 mm), made of low dielectric material (for example, made of ceramic) arranged on both sides and the upper surface of each ejection electrode 211a. The partition wall 223 is provided.

【0036】

Each of the discharge electrodes 211a is made of a metal such as copper or nickel, and a low-dielectric film (for example, a polyimide film) for preventing pigment adhesion having good wettability is formed on the surface thereof. The tip of each ejection electrode 211a is formed into a triangular pyramid shape, and each protrudes from the ink ejection hole 222 toward the counter electrode 210 by an appropriate length (70 μm to 80 μm).

【0037】

When a drive circuit (not shown) described above gives a control signal to the pulse voltage generator 213 for a time corresponding to the gradation data included in the image data according to the control of the controller, the pulse voltage generator 213 A high voltage signal in which the pulse Vp of the pulse top corresponding to the type of the control signal is placed on the bias voltage Vb is superimposed on the bias voltage Vb and output.

【0038】

Then, when the image data is transferred, the controller drives two pumps 214a and 214b of the ink circulation system. As a result, the ink is pumped from the ink supply unit 220a and the ink collection unit 220b becomes negative pressure, and the ink flowing through the ink flow path 221 crawls up the gaps of the partition walls 223 by capillary action, and each ejection electrode. Wet and spread to the tip of 211a. At this time, since a negative pressure is applied to the ink liquid level near the tip of each discharge electrode 211a, an ink meniscus is formed at the tip of each discharge electrode 211a.

【0039】

Further, by controlling the recording medium transport mechanism by the controller, the recording medium 230 is sent in the predetermined direction indicated by the arrow in the figure, and by controlling the drive circuit, the recording medium 230 and the discharge electrode 211a are described above. High voltage signal is applied.

【0040】

The behavior of the meniscus up to the flight of droplets in the inkjet device disclosed in Patent Document 2 will be described below with reference to FIGS. 21 to 24.

【0041】

As shown in FIG. 21, when the pulse voltage from the pulse voltage generator 213 is applied to the discharge electrode 211a in the recording head 211, an electric field is generated from the discharge electrode 211a side to the counter electrode 210 side. Here, since the discharge electrode 211a with a sharp tip is used, the strongest electric field is generated near the tip.

【0042】

When such an electric field is generated, as shown in FIG. 22, each of the individual charged pigment particles 201a in the ink solvent moves toward the ink liquid surface by the force fE (FIG. 21) exerted from this electric field. As a result, the pigment concentration near the ink liquid surface is concentrated.

【0043】

When the pigment concentration is concentrated in this way, as shown in FIG. 23, a plurality of charged pigment particles 201a start to agglomerate near the ink liquid surface due to the opposite side of the electrode. Then, when the pigment aggregate 201 begins to grow spherically near the ink liquid surface, the electrostatic repulsive force fcon from the pigment aggregate 201 begins to act on each of the charged pigment particles 201a. That is, the electrostatic repulsive force fcon from the pigment aggregate 201 and the resultant force ftotal of the force fE from the electric field E due to the pulse voltage act on each of the charged pigment particles 201a.

【0044】

Therefore, as long as the electrostatic repulsive force between the charged pigment particles does not exceed the mutual cohesive force, the charged pigment particles 201a (the tip of the discharge electrode 211a and the pigment agglomerate) on which the resultant force ftotal toward the pigment agglomerate 201 acts. If the force fE exerted by the electric field on the charged pigment particles 201a) on the straight line connecting the center of 201 exceeds the electrostatic repulsive force fcon from the pigment aggregate 201 (fE fcon), the charged pigment particles 201a are pigments. It grows into aggregate 201.

【0045】

The pigment aggregate 201 formed from n charged pigment particles 201a receives an electrostatic repulsive force FE from an electric field E due to a pulse voltage, and a binding force Fesc from an ink solvent. When the electrostatic repulsive force FE and the binding force Fesc are balanced, the pigment agglomerate 201 stabilizes in a state of slightly protruding from the ink liquid surface.

【0046】

Further, when the pigment aggregate 201 grows and the electrostatic repulsive force FE exceeds the binding force Fesc, the pigment aggregate 201 starts from the ink liquid level 200a as shown in FIGS. 24 (a) to 24 (c). Escape.

【0047】

By the way, in the principle of the conventional electrostatic suction method, the electric charge is concentrated in the center of the meniscus to generate a bulge of the meniscus. The radius of curvature of the tip of this raised tailor cone is determined by the amount of concentrated charge, and the separation of droplets begins when the amount of concentrated charge and the electrostatic force due to the electric field strength then outweigh the surface tension of the meniscus.

【0048】

Since the maximum charge amount of the meniscus is determined by the physical property value of the ink and the radius of curvature of the meniscus, the minimum droplet size is determined by the physical property value of the ink (particularly the surface tension) and the electric field strength formed in the meniscus portion.

【0049】

In general, the surface tension of a liquid tends to be lower when it contains a solvent than when it contains a pure solvent, and since various solvents are contained in actual ink, it is not possible to increase the surface tension. difficult. Therefore, a method is adopted in which the surface tension of the ink is considered to be constant and the droplet size is reduced by increasing the electric field strength.

【0050】

[Patent Document 1]

Japanese Unexamined Patent Publication No. 8-238774 (published on September 17, 1996) [0051]

[Patent Document 2]

Japanese Unexamined Patent Publication No. 2000-127410 (published on May 9, 2000) [0052]

[Patent Document 3]

Japanese Unexamined Patent Publication No. 58-31757 (published on February 24, 1983) [0053]

[Patent Document 4]

Japanese Unexamined Patent Publication No. 10-175305 (published on June 30, 1998) [0054]

[Patent Document 5]

Japanese Unexamined Patent Publication No. 11-42784 (published on February 16, 1999) [0055]

[Problems to be Solved by the Invention]

However, as described above, in the conventional electrostatic suction method, a method of reducing the droplet size by increasing the electric field strength is adopted, but in the inkjet apparatus disclosed in the above Patent Documents 1 and 2, the method is adopted. As a principle of ejection, both of them concentrate the charge in the center of the meniscus by forming a field of strong electric field strength in the meniscus region having an area much larger than the projected area of the ejected droplet, and form the concentrated charge. It is necessary to apply a very high voltage close to 2000V because the discharge is performed by the electrostatic force consisting of the existing electric field strength. As a result, it is difficult to control the drive, and there is also a problem in terms of safety in operating the inkjet device.

【0056】

As a result of diligent studies in view of such problems, the inventors of the present application have found that below a certain nozzle diameter, a ejection phenomenon occurs in an ejection model different from the conventional fluid ejection model, and a portion where ink is ejected (ejection start). It was found that the electric field strength can be increased without applying a high voltage by reducing the width or diameter of the part).

【0057】

Here, with reference to FIGS. 25 (a) and 25 (b), the basic characteristics of electrostatic suction type trace fluid discharge, particularly the surface potential due to the electric charge accumulated in the meniscus at the tip of the nozzle will be considered.

【0058】

First, as shown in FIG. 25 (a), a simple configuration of an electrostatic suction type fluid discharge device is modeled. In the simple model, the drive electrode 251 is installed inside the pointed nozzle 250, and the discharge material 252 is filled in the entire nozzle interior. The substrate 254 is arranged so as to face the tip surface of the nozzle, and is grounded by the back electrode 255.

【0059】

In the case of such a simple configuration model, when the electric charge flowing out from the power supply 256 passes through the fluid 252 which is the discharge material inside the nozzle 250 and faces the substrate 254 on the meniscus 257 having a capacitance at the nozzle tip. Therefore, the power supply voltage V as shown in Fig. 25 (b).₀It can be assumed that the electric resistance R inside the nozzle and the capacitance C between the meniscus 257 and the substrate 254 are a series circuit.

【0060】

V₀In the RC series circuit, the accumulated charge Q (t) on the meniscus 257 can be expressed as follows.

【0061】

R dQ (t) / dt + Q (t) / C = V₀ (5) By solving the differential equation of Eq. (5), the accumulated charge Q (t) on the surface of the meniscus and the surface potential V (t) of the meniscus can be expressed as follows.

【0062】

Q (t) = CV₀[1-exp (-t / RC)] (6) V (t) = V₀[1-exp (-t / RC)] (7) As described above, the accumulated charge Q (t) on the meniscus surface and the meniscus surface potential V (t) at a certain time t are the nozzle 250. It can be seen that it depends on the internal electrical resistance R and the capacitance C between the meniscus 257 and the substrate 254. That is, in the electrostatic suction type fluid discharge device having such a configuration, by reducing the electric resistance R inside the nozzle 250, electric charges are likely to be accumulated on the surface of the meniscus 257, and the time required for discharging the fluid 252 is reduced. Can be shortened. That is, the discharge frequency can be improved, and high-speed drawing becomes possible.

【0063】

As a specific measure to reduce the electric resistance R inside the nozzle 250, it is desirable to bring the drive electrode 251 as close to the tip of the nozzle 250 as possible.

【0064】

Patent Document 4 discloses a technique for forming an electrode inside a nozzle hole of an electrostatic suction type inkjet nozzle. FIG. 26 is a cross-sectional view showing the nozzle plate manufacturing process in Patent Document 4. The structure of Patent Document 4 will be described with reference to FIG. 26.

【0065】

In the figure, 301 is a nozzle plate, and a plurality of ink collecting recesses A ... Are formed in advance in the nozzle plate 301, and the ink collecting recesses A ... of the nozzle plate 301 are not formed on the surface. , The resist layer 302 that does not fix the conductive plating 303 is coated. Then, after the nozzle holes B penetrating the nozzle plate 301 and the resist layer 302 are formed so as to communicate with the respective ink pool recesses A, the conductive plating 303 is applied to the inner circumference of the nozzle. Here, since a material from which the conductive plating 303 is not fixed is selected for the resist layer 302, the conductive plating 303 is fixed only inside the nozzle plate 301 and on the surface of the nozzle plate 301 on which the resist layer 302 is not formed. Will be done. In this way, in Patent Document 4, an electrode layer (conductive plating 303) is formed inside the nozzle hole.

【0066】

Further, Patent Document 5 discloses a configuration in which an electrode is formed on a recording medium facing surface of a nozzle plate of an electrostatic suction type inkjet head. FIG. 27 is an explanatory diagram showing the configuration of the inkjet head according to Patent Document 5. Patent Document 5 will be described with reference to FIG. 27.

【0067】

In the inkjet head, the control electrode 401 is formed on the front surface of the insulation control substrate 411 and the control electrode 402 is formed on the back surface thereof, and the ink jet head penetrates the control electrode 401 or 402 from the ink tank 430 so that ink can pass therethrough. The ink ejection hole 413 is formed. An ink guide 412 having protrusions is arranged in the ink ejection hole 413, and the electric field due to the voltage applied to the control electrodes 401 and 402 is concentrated on the tip of the ink guide 412, and the ink droplet 414 is generated by this electric field. It flies to the recording medium 421 installed via the counter electrode 420.

【0068】

However, the methods disclosed in Patent Documents 4 and 5 have the following problems and cannot be applied to an electrostatic suction type fluid discharge device in which the width or diameter of the ink ejection portion is reduced. ..

【0069】

First, regarding the configuration of Patent Document 4, according to this, since the conductive plating 303 is formed in a region other than the medium facing surface of the nozzle plate 301, the recesses A for collecting ink and the nozzle holes B are filled with the conductive plating 303. The formed conductive plating 303 is electrically short-circuited with each other. Therefore, in such a nozzle plate 301, it is not possible to eject only one specific channel, and in order to improve the resolution of the drawn image, it is necessary to electrically separate the adjacent channels.

【0070】

As the method, for example, the following methods (1) and (2) can be considered. (1) After forming the conductive plating 303, the ink inflow surface side on which the ink pool recess A ... of the nozzle plate 301 is formed is processed to divide the conductive plating 303 for each channel. (2) Before forming the conductive plating 303, a resist layer similar to the ejection surface is formed on the ink inflow surface side of the nozzle plate 301 to create a region where the conductive plating 303 does not adhere.

【0071】

However, in the method of dividing after forming the layer of conductive plating 303 of (1), if machining is used for the dividing process, dust such as cutting chips enters the nozzle hole B, causing nozzle blockage and heat such as laser. In the dividing process using the above, the stress due to heat remains and the nozzle plate 301 is deformed by the above stress.

【0072】

Further, it is conceivable to perform the dividing process by etching, but when etching is used, it is necessary to form a resist pattern on the conductive plating 303 formed on the ink inflow surface side of the nozzle plate. As described above, in the case of a nozzle plate applied to an electrostatic suction type fluid ejection device in which the width or diameter of the portion where ink is ejected is reduced, the nozzle plate has a nozzle hole of 10 μm or less, so that the nozzle hole diameter is processed. In order to improve the accuracy, it is desirable to use a nozzle plate base material of about 50 μm. However, since such a thin nozzle plate has low rigidity, it is easily deformed in handling the nozzle plate when creating a resist pattern, and it is not possible to form a pattern with high accuracy.

【0073】

The same applies to the method of (2) above. Since the nozzle plate itself is thin, deformation of the nozzle plate becomes a problem even before forming the conductive plating 303, and a resist pattern can be formed with high accuracy. Therefore, good channel separation cannot be performed.

【0074】

Further, the method of Patent Document 4 has a problem that when the nozzle hole diameter is as small as 10 μm or less, the plating solution is not sufficiently supplied and it is extremely difficult to stably form conductive plating inside the nozzle hole. In this case, it is the tip of the nozzle that the supply of the plating solution is most insufficient. As described above, it is desirable to bring the electrode as close to the tip of the nozzle as possible, which makes it impossible to stably form the electrode at the tip of the nozzle, which is the most important.

【0075】

That is, the smaller the nozzle diameter, the smaller the amount of fluid that can be discharged, and the better the drawing resolution, but on the other hand, the formation of electrodes becomes unstable. Therefore, the electric resistance R inside the nozzle at the tip of the nozzle changes for each channel, which causes the response frequency to change for each channel, making it difficult to uniformly control the appropriate amount of discharged liquid between the channels. That is, the print quality of the drawn image is significantly deteriorated.

【0076】

On the other hand, in the insulation control substrate 411 corresponding to the nozzle plate disclosed in Patent Document 5, since the control electrode 401 is formed on the surface facing the recording medium 421, the position of the electrode with respect to the meniscus is set with extremely high accuracy. can do. Therefore, there is no problem as in the configuration of Patent Document 4, the discharge stability between the channels is high, and the electrical separation from the adjacent channels is sufficient.

【0077】

However, as shown in FIG. 28, in the configuration of Patent Document 5, a lead-out wiring 405 for applying a voltage from the voltage applying means to the control electrode 401 is also formed at the same time on the facing surface of the recording medium 421 in the insulation control board 411. However, in this case, an electric field is also generated from the lead-out wiring 405. In particular, a concentrated electric field is likely to be generated from the bent portion 405a of the lead-out wiring 405, and there is a high risk that the electronic component will be damaged by the electric field, for example, when drawing on an electric component.

【0078】

The present invention has been made in view of the above problems, and is a nozzle plate that can be suitably used for an electrostatic suction type fluid discharge device that discharges an ultra-trace amount of fluid, and is stable in the vicinity of the nozzle tip. The electrodes can be formed, it is easy to make the plurality of nozzle holes electrically independent, and the drive signal is applied to the electrodes formed in the nozzle holes from the fluid supply side of the nozzle plate. It is an object of the present invention to provide a nozzle plate which can be carried out and a method for manufacturing the same.

【0079】

[Means for solving problems]

In order to solve the above problems, the nozzle plate of the present invention is provided in an electrostatic suction type fluid discharge device that discharges a fluid charged by applying a voltage from a fluid discharge hole at the tip of the nozzle by electrostatic suction, and has a plurality of nozzles. In a nozzle plate having a hole, a thin first nozzle layer having a first nozzle hole and arranged on the fluid discharge side is laminated on the fluid supply side of the first nozzle layer, and the above-mentioned first It is provided with at least one second nozzle layer which is thicker than the first nozzle layer and has a second nozzle hole which communicates with the first nozzle hole and forms a nozzle hole portion with the first nozzle hole. The feature is that the first electrode layer formed on the inner wall of the first nozzle hole and the second electrode layer formed on the inner wall of the second nozzle hole are electrically connected. It is supposed to be.

【0080】

According to the above configuration, the nozzle plate has a configuration in which at least one thick second nozzle layer is laminated on the thin first nozzle layer, so that the strength and rigidity of the nozzle plate itself are second. It can be secured by the nozzle layer of the above, and the thickness of the first nozzle layer can be sufficiently thinned. By reducing the layer thickness, the first nozzle hole formed in the first nozzle layer can be formed into an ultrafine hole having a hole diameter of, for example, 10 μm or less, and such an ultrafine first nozzle. A first electrode layer can be stably formed on the inner wall of the hole in the layer thickness direction, and when the opening of the first nozzle hole on the fluid discharge surface is a fluid discharge hole, it is located near the fluid discharge hole. The first electrode can be formed up to. As a result, the electric resistance R inside the nozzle can be dramatically reduced as compared with the conventional case, the discharge frequency of the fluid can be improved, and high-speed drawing on the recording medium becomes possible.

【0081】

Moreover, since the first electrode layer formed in this way is electrically connected to the second electrode layer formed in the second nozzle hole communicating with the first nozzle hole, the second electrode layer is second. A drive signal can be supplied from the fluid supply side of the nozzle plate via the electrode layer. Therefore, the lead-out wiring for supplying the drive signal to the first electrode layer does not come close to the medium, and the recording medium is not electrically damaged by the electric field generated from the lead-out wiring.

【0082】

In the nozzle plate of the present invention, the first electrode layer is further extended from the first nozzle hole onto the first nozzle layer at the interface between the first nozzle layer and the second nozzle layer. The second electrode layer can also be characterized in that it is electrically connected to the first electrode layer at a portion extending over the first nozzle layer.

【0083】

According to the above configuration, the first electrode layer extends from the first nozzle hole onto the first nozzle layer at the interface between the first nozzle layer and the second nozzle layer, and the second electrode layer is Since this extension is electrically connected to the first electrode layer, the connection between the first electrode layer and the second electrode layer is performed not on the cross section of each electrode layer but on the surface of the electrode layer. ing. Therefore, although the configuration is such that different electrode layers are connected to each other, the electrical connection reliability between the electrode layers is high, and there is a great risk that the drive signal cannot be satisfactorily applied to the first electrode layer due to disconnection or the like. It can be reduced and the discharge reliability can be improved.

【0084】

Further, the nozzle plate of the present invention can be further characterized in that the first electrode layer is formed on the entire inner wall of the first nozzle hole.

【0085】

In the above configuration, since the first electrode layer is formed on the entire inner wall of the first nozzle hole, a uniform electric field can be applied to the fluid in the fluid discharge hole. For example, in the case of a configuration in which a plurality of fluid discharge holes are provided on the fluid discharge surface of the nozzle plate, the landing accuracy is lowered if the formation position of the tailor cone is different for each fluid discharge hole. The formation position of the corn is stable, and the landing accuracy can be improved.

【0086】

Further, in the nozzle plate of the present invention, the first electrode layer is further extended from the first nozzle hole onto the first nozzle layer at the interface between the first nozzle layer and the second nozzle layer. The opening on the side communicating with the first nozzle hole in the second nozzle hole is characterized to be located in the first electrode layer portion extending on the first nozzle layer. You can also.

【0087】

According to the above configuration, at the interface between the first nozzle layer and the second nozzle layer, the first electrode layer extends over the first nozzle layer, and the first in the second nozzle hole. Since the opening on the side communicating with the nozzle hole is arranged, the extended portion of the first electrode layer functions as an etching stopper portion when etching the second nozzle hole, and the second nozzle Etching during hole formation does not damage and deform the first nozzle hole or the first nozzle layer.

【0088】

As described above, if the first nozzle layer outside the extended portion of the first electrode layer is etched, the first electrode layer is separated and removed from the nozzle plate, but it is stable due to the above configuration. The nozzle plate can be manufactured.

【0089】

Further, in the nozzle plate of the present invention, the first nozzle hole and / or the second nozzle hole may be characterized in that an opening on the fluid supply side is formed larger than that on the fluid discharge side. ..

【0090】

According to the above configuration, since the first nozzle hole and / or the second nozzle hole is formed with a taper so that the fluid supply side becomes wider, the inner wall surface of the nozzle hole and the first nozzle layer Alternatively, the angle formed by each surface of the second nozzle layer becomes an obtuse angle. As a result, when the first or second electrode layer is formed from the inner wall surface of the first nozzle hole or the second nozzle hole to the surface of each nozzle layer, the electrode layer is disconnected due to the angle formed by the inner wall surface and the surface of the nozzle layer. It is possible to form an electrode layer having a low risk of forming and having high conductivity reliability. Further, when the discharged liquid is supplied to the tip of the nozzle, there is little risk of turbulence occurring in the nozzle, and the discharged liquid can be stably supplied.

【0091】

Further, in the nozzle plate of the present invention, a surface electrode layer having a through hole is further arranged on the fluid discharge side of the first nozzle hole so as to close the fluid discharge side opening of the first nozzle hole. It can also be characterized in that the through hole and the first nozzle hole communicate with each other and the surface electrode layer is electrically connected to the first electrode layer.

【0092】

According to the above configuration, the through hole of the surface electrode layer provided on the fluid discharge surface of the nozzle plate becomes the fluid discharge hole, so that the fluid discharge hole that greatly affects the landing accuracy of the discharged fluid is etched by the surface electrode layer. Can be processed. As a result, the shape accuracy of the fluid discharge hole is dramatically stabilized as compared with the configuration in which the fluid discharge side opening of the first nozzle hole in which the first electrode layer is formed on the inner wall is used as the fluid discharge hole. Along with this, the landing accuracy can be further stabilized.

【0093】

Further, in the nozzle plate of the present invention, the second electrode layer in the second nozzle layer on the most fluid supply side is located on the fluid supply side of the second nozzle layer between adjacent nozzle holes. It can also be characterized by being electrically separated.

【0094】

According to the above configuration, in a nozzle plate having a plurality of nozzle holes, the second electrode layer of the second nozzle layer on the most fluid supply side is adjacent to the second electrode layer on the fluid supply side of the second nozzle layer. Since the nozzle holes are electrically separated from each other, it is possible to drive a plurality of nozzle holes independently, and high-resolution drawing becomes possible.

【0095】

Further, in the nozzle plate of the present invention, the second electrode layer of the second nozzle layer, which is closest to the fluid supply side, is also formed on the fluid supply side surface of the second nozzle layer, and is formed on the surface. It can also be characterized in that it is patterned to form a lead-out wiring.

【0096】

According to the above configuration, the second electrode layer of the second nozzle layer on the most fluid supply side is used as the lead wiring on the fluid discharge side surface of the second nozzle layer, so that it can be used in the lead wire processing step. At the same time, the second electrode layer can be electrically separated between the adjacent nozzle holes. Therefore, the separation process and the lead-out wiring forming process become one process, and the process can be simplified. Further, since the second electrode layer formed on the inner wall of the second nozzle hole and the lead-out wiring are formed by processing the same electrode layer, the connection reliability between the second electrode layer and the lead-out wiring is improved. Very expensive.

【0097】

Further, the nozzle plate of the present invention is further characterized in that the diameter of the opening on the fluid discharge side of the first nozzle hole or the diameter of the through hole formed in the surface electrode layer is 8 μm or less. You can also.

【0098】

By setting the nozzle discharge hole diameter to a fine diameter of 0.01 to 25 μm, the applicants of the present application generate a local electric field according to the new discharge model proposed by the inventors of the present application, and drive the nozzle by making the nozzle fine. We have previously announced that it will be possible to reduce the voltage. Such a decrease in the drive voltage is extremely advantageous in reducing the size of the device and increasing the density of the nozzles. Of course, by lowering the drive voltage, it is possible to use a low-voltage drive driver with a high cost merit, and it is possible to improve the safety in use.

【0099】

Further, in the above discharge model, the electric field strength required for discharge depends on the local concentrated electric field strength, so that the presence of the counter electrode is not essential. That is, it is possible to print on an insulating substrate or the like without the need for a counter electrode, which increases the degree of freedom in device configuration and also enables printing on a thick insulator. ..

【0100】

Above all, by setting the diameter of the fluid discharge hole of the nozzle to φ8 μm or less as described above as in the above configuration, the electric field strength distribution is effectively concentrated in the vicinity of the discharge surface of the fluid discharge hole, and the counter electrode Since the fluctuation of the distance from the to the fluid discharge hole does not affect the electric field strength distribution, stable fluid discharge can be performed without being affected by the position accuracy of the counter electrode, the material characteristics of the recording medium, and the thickness variation. It can be carried out.

【0101】

In addition, since the electric field strength distribution can be effectively concentrated near the discharge surface of the fluid discharge hole, a strong electric field can be stably formed in a narrow region, and an ultratrace amount of fluid can be reliably discharged, and a printed image can be printed with high resolution. It becomes possible to.

【0102】

In the method for manufacturing a nozzle plate of the present invention, in order to solve the above-mentioned problems, a step of forming a sacrificial layer on a substrate, a step of forming a first nozzle layer on the sacrificial layer, and the above-mentioned first nozzle A step of forming a plurality of first nozzle holes in the layer, a step of forming a first electrode layer on the first nozzle layer including the inner wall surface of each first nozzle hole, and a step of forming each first Including the step of processing the first electrode layer so as to remain on the inner wall of the nozzle hole and the peripheral portion of each first nozzle hole, and each remaining first electrode layer portion on the first nozzle layer. The step of forming the second nozzle layer, a plurality of second nozzle holes in the second nozzle layer, and openings on the fluid discharge side of each second nozzle hole remain on the first nozzle layer. Adjacent to the step of forming the second electrode layer so as to fit in each of the first electrode layer portions and the step of forming the second electrode layer on the second nozzle layer including the inner wall surface of each second nozzle hole. It is characterized by including a step of processing the second electrode layer so as to be electrically separated between the second nozzle holes.

【0103】

According to this, the first nozzle layer, the first electrode layer, the second nozzle layer, and the second electrode layer are sequentially laminated on the highly rigid substrate via the sacrificial layer. Therefore, after forming a resist pattern using photolithography technology, it can be processed into a desired shape by dry etching, so that the first nozzle hole, the second nozzle hole, the first electrode layer, and the second electrode layer can be processed. Can be formed with very high shape accuracy.

【0104】

Further, since the fluid discharge surface of the nozzle plate is protected by the sacrificial layer until the final stage of the process, there is no danger that the fluid discharge hole is damaged and the fluid discharge hole is deformed in the nozzle plate manufacturing process. Therefore, the manufacturing yield of the nozzle plate is improved.

【0105】

Further, in the method for manufacturing a nozzle plate of the present invention, a surface electrode layer is further formed on the sacrificial layer between the step of forming the sacrificial layer on the substrate and the step of forming the first nozzle layer on the sacrificial layer. In the step of forming the first nozzle layer on the sacrificial layer, which has a step of forming the surface electrode layer corresponding to the nozzle hole forming portion and forming a through hole in each separating portion. It can also be characterized by forming a first nozzle layer including on the separated surface electrode layer.

【0106】

In the method for manufacturing a nozzle plate having this configuration, since a fluid discharge hole can be formed as a through hole in the surface electrode layer formed on the sacrificial layer, the first electrode layer formed in the first nozzle hole can be formed. Due to the non-uniformity (for example, film thickness distribution), the shape of the fluid discharge hole is not deformed, and a nozzle plate having a highly accurate fluid discharge hole can be manufactured.

【0107】

Further, the method for manufacturing a nozzle plate of the present invention can also be characterized in that the film-forming particles are obliquely incident on the surface of the nozzle plate in the step of forming the second electrode layer.

【0108】

Further, the method for manufacturing a nozzle plate of the present invention can also be characterized in that the film-forming particles are obliquely incident on the surface of the nozzle plate in the step of forming the first electrode layer.

【0109】

The electrode layers (first and second) formed by obliquely incident film-forming particles have good adhesion to the side wall of the nozzle hole. Further, since the electrode layer is not formed in the region that is shaded by the sputtering target or the vapor deposition source, for example, the inside of the first nozzle hole when forming the second electrode layer or the first electrode layer is formed. A region where the electrode layer is not desired to be formed, such as the inside of the through hole formed in the surface electrode layer at the time of the operation, can be formed as the shadow portion. As a result, the region where the electrode layer is formed and the region where the electrode layer is not formed can be easily set, and the adhesiveness of the electrode layer inside the nozzle hole forming the electrode layer can be enhanced.

【0110】

Further, in the method for manufacturing a nozzle plate of the present invention, etching is used in the step of forming the second nozzle hole, and the etching of the first electrode layer is more important than the resistance to etching of the second nozzle layer. It can also be characterized by selecting conditions that are highly resistant to.

【0111】

According to this, since the etching for forming the second nozzle hole can be accurately stopped by the first electrode layer, the first nozzle hole and the first nozzle layer can be used for processing the second nozzle hole. A nozzle plate with high shape accuracy can be manufactured without being damaged by overetching.

【0112】

Further, in the method for manufacturing a nozzle plate of the present invention, etching is used in the step of forming the first nozzle hole and the step of forming the second nozzle hole, and etching of each of the first and second nozzle layers is performed. It is also possible to select a condition in which the resistance to etching of the surface electrode layer is higher than the resistance to etching.

【0113】

According to this, the surface electrode layer is not damaged by the overetching at the time of forming the first nozzle hole or the overetching at the time of forming the second nozzle hole. Therefore, the fluid discharge hole formed of the through hole of the surface electrode layer is not deformed by overetching and the landing accuracy is not deteriorated, and a nozzle plate having a stable and high landing accuracy can be manufactured.

【0114】

Further, the method for manufacturing a nozzle plate of the present invention can be further characterized in that the step of electrically separating the second electrode layer is performed by using dry etching.

【0115】

According to this, since the separation processing of the second electrode layer is performed by dry etching, the shape accuracy of the processing is high, and the electrode layer material in the work area is removed in the gas phase, so that processing such as Kiriko is performed. There is no risk of dust entering the first and second nozzle holes and blocking the nozzle holes. Therefore, a nozzle plate having high discharge reliability can be stably manufactured.

【0116】

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described below.

【0117】

[Prerequisite configuration]

First, the electrostatic suction type fluid discharge device, which is the premise configuration of the present invention to which the nozzle plate according to the present invention is applied, will be described with reference to FIGS. 1 to 6.

【0118】

The electrostatic suction type fluid discharge device, which is a prerequisite configuration of the present invention, has a nozzle diameter of 0.01 μm to 25 μm and enables fluid discharge control with a drive voltage of 1000 V or less.

【0119】

Here, in the conventional fluid ejection model, a decrease in the nozzle diameter leads to an increase in the drive voltage. Therefore, if the nozzle diameter is 50 to 70 μm or less, unless other measures such as applying back pressure to the ejected ink are taken. It was thought that it was impossible to eject ink at a drive voltage of 1000 V or less. However, as a result of diligent studies, the inventors of the present application have found that a discharge phenomenon occurs in a discharge model different from the conventional fluid discharge model below a certain nozzle diameter. The present invention has been made based on new findings in this fluid discharge model.

【0120】

First, the fluid discharge model discovered by the inventors of the present application will be described.

【0121】

It is assumed that a conductive fluid is injected into a nozzle of diameter d (in the following description, it refers to the inner diameter of the nozzle unless otherwise specified) and is positioned perpendicular to the height h from the infinite flat plate conductor. This is shown in Fig. 1. At this time, it is assumed that the electric charge Q induced in the nozzle tip (nozzle hole) is concentrated in the hemisphere formed by the fluid at the nozzle tip, and is approximately expressed by the following equation.

【0122】

[Number 1]<img file="JP2005074635A_D0001.tif" /> 【0123】

Here, Q: Charge (C) induced at the tip of the nozzle, ε₀: Vacuum permittivity (F / m), d: Nozzle diameter (m), V₀: The total voltage applied to the nozzle. In addition, α is a proportional constant that depends on the nozzle shape, etc., and takes a value of about 1 to 1.5. In particular, d &lt;&lt; h (h: nozzle (to be exact, nozzle hole) -distance between substrates (m)) At the time of, it becomes almost 1.

【0124】

Further, when a conductive substrate is used as the substrate, it is considered that a mirror image charge Q'having a polarity opposite to the charge Q is induced at a symmetrical position in the substrate facing the nozzle. When the substrate is an insulator, the image charge Q'having the opposite polarity to the charge Q is similarly induced at the symmetrical position determined by the dielectric constant.

【0125】

Concentrated electric field strength E at the tip of the nozzle_locAssuming that the radius of curvature of the tip is R, [0126]

[Number 2]<img file="JP2005074635A_D0002.tif" /> 【0127】

Given in. Here, k is a proportionality constant that depends on the nozzle shape, etc., and takes a value of about 1.5 to 8.5, but in most cases it is considered to be about 5 (PJ Birdseye and DA Smith, Surface Science, 23 (1970), p.198-210). Also, here, in order to simplify the fluid discharge model, it is assumed that R = d / 2. This corresponds to a state in which the fluid rises in a hemispherical shape having the same curvature diameter as the nozzle diameter d due to surface tension at the nozzle tip.

【0128】

Consider the balance of pressure acting on the fluid at the tip of the nozzle. First, the electrostatic pressure P_eIs [0129], where S is the liquid area at the tip of the nozzle.

[Number 3]<img file="JP2005074635A_D0003.tif" /> 【0130】

Will be. From equations (8) to (10), pressure P_eIs set to α = 1, [0131]

[Number 4]<img file="JP2005074635A_D0004.tif" /> 【0132】

It is expressed as.

【0133】

On the other hand, the pressure P due to the surface tension of the fluid at the tip of the nozzle._sThen, [0134]

[Number 5]<img file="JP2005074635A_D0005.tif" /> 【0135】

Will be. Here, γ: surface tension. The condition that discharge occurs due to electrostatic force is that the electrostatic force exceeds the surface tension, so the electrostatic pressure P_eAnd pressure due to surface tension P_sThe relationship with [0136]

[Number 6]<img file="JP2005074635A_D0006.tif" /> 【0137】

Will be.

【0138】

Figure 2 shows the pressure P due to surface tension when a nozzle with a certain diameter d is given._sAnd electrostatic pressure P_eShow the relationship with. As the surface tension of the fluid, it is assumed that the fluid is water (γ = 72 mN / m). When the voltage applied to the nozzle is 700V, the electrostatic pressure P is when the nozzle diameter d is 25 μm._eIs the pressure due to surface tension P_sIt is suggested that it exceeds. From this, V₀When the relationship between and d is calculated, [0139]

[Number 7]<img file="JP2005074635A_D0007.tif" /> 【0140】

Gives the minimum discharge voltage.

【0141】

The discharge pressure ΔP at that time is [0142].

[Number 8]<img file="JP2005074635A_D0008.tif" /> 【0143】

From [0144]

[Number 9]<img file="JP2005074635A_D0009.tif" /> 【0145】

Will be.

【0146】

Fig. 3 shows the dependence of the discharge pressure ΔP when the discharge condition is satisfied by the local electric field strength for a nozzle with a certain diameter d, and the dependence of the discharge critical voltage (that is, the minimum voltage at which discharge occurs) Vc. Shown in 4.

【0147】

From Fig. 3, when the discharge condition is satisfied by the local electric field strength (V)₀It can be seen that the upper limit of the nozzle diameter (assuming = 700V, γ = 72mN / m) is 25μm.

【0148】

In the calculation of FIG. 4, water (γ = 72 mN / m) and an organic solvent (γ = 20 mN / m) were assumed as fluids, and the condition of k = 5 was assumed. From this figure, it is clear that the discharge critical voltage Vc decreases as the nozzle diameter decreases, considering the concentration effect of the electric field by the fine nozzle. When the fluid is water and the nozzle diameter is 25 μm, the discharge critical voltage It can be seen that Vc is about 700V.

【0149】

The concept of electric field in the conventional discharge model, that is , the voltage V applied to the nozzle₀When only the electric field defined by the nozzle-opposite electrode distance h is considered, the drive voltage required for ejection increases as the nozzle diameter becomes smaller.

【0150】

On the other hand, if attention is paid to the local electric field strength as in the new discharge model proposed by the inventors of the present application, it is possible to reduce the drive voltage in discharge by making the nozzle finer. Such a decrease in the drive voltage is extremely advantageous in reducing the size of the device and increasing the density of the nozzles. Of course, by lowering the drive voltage, it is possible to use a low voltage drive driver with high cost merit.

【0151】

Further, in the above discharge model, the electric field strength required for discharge depends on the local concentrated electric field strength, so that the presence of the counter electrode is not essential. That is, in the conventional discharge model, since an electric field is applied between the nozzle and the substrate, it is necessary to arrange a counter electrode on the side opposite to the nozzle or make the substrate conductive with respect to the insulator substrate. .. When the counter electrode is arranged, that is, when the substrate is an insulator, there is a limit to the thickness of the substrate that can be used.

【0152】

On the other hand, in the discharge model of the present invention, printing can be performed on an insulating substrate or the like without requiring a counter electrode, which increases the degree of freedom in device configuration. In addition, it is possible to print on a thick insulator.

【0153】

Further, FIG. 5 shows the correlation between the magnitude of the mirror image force acting on the substrate and the distance h from the substrate. As is clear from the figure, this mirror image force becomes more remarkable as the distance between the substrate and the nozzle becomes closer, especially when h is 20 μm or less.

【0154】

Next, let us consider the precise control of the discharge flow rate. In the case of a viscous flow, the flow rate Q in the cylindrical flow path is expressed by the following Hagen-Poiseuille equation. Now, assuming a cylindrical nozzle, the flow rate Q of the fluid flowing through this nozzle is expressed by the following equation.

【0155】

[Number 10]<img file="JP2005074635A_D0010.tif" /> 【0156】

Here, η: viscosity coefficient of fluid (Pa · s), L: flow path, that is, nozzle length (m), d: flow path, that is, nozzle hole diameter (m), ΔP: pressure difference (Pa). is there. From the above equation, since the flow rate Q is proportional to the fourth power of the radius of the flow path, it is effective to use a fine nozzle to limit the flow rate. Substituting the discharge pressure ΔP obtained by Eq. (16) into Eq. (17), the following equation is obtained.

【0157】

[Number 11]<img file="JP2005074635A_D0011.tif" /> 【0158】

This equation represents the amount of fluid flowing out of the nozzle when a voltage V is applied to the nozzle having a diameter d and a length L. This is shown in Fig. 6. The values of L = 10 mm, η = 1 (mPa · s), and γ = 72 (mN / m) were used for the calculation. Now, assume that the nozzle diameter is the minimum value of 50 μm in the prior art. When the voltage V is gradually applied, the discharge starts at the voltage V = 1000V. This voltage corresponds to the discharge start voltage described in FIG. The flow rate from the nozzle at that time is shown on the Y-axis. The flow rate rises rapidly just above the discharge start voltage Vc.

【0159】

In this model calculation, it seems that a minute flow rate can be obtained by precisely controlling the voltage slightly above Vc, but as expected from the semi-logarithmic diagram, it is practically impossible, especially. Ten^-10m³It is difficult to realize a minute amount below / s. Further, when a nozzle having a certain diameter is adopted, the minimum drive voltage is determined as given by the equation (14). Therefore, as long as a nozzle with a diameter of 50 μm or more is used as in the prior art, 10^-10m³It is difficult to set a minute discharge amount of / s or less and a drive voltage of 1000V or less.

【0160】

As can be seen from the figure, a driving voltage of 700 V or less is sufficient for a nozzle with a diameter of 25 μm, and control is possible even with a drive voltage of 500 V or less for a nozzle with a diameter of 10 μm. It can also be seen that in the case of a nozzle with a diameter of 1 μm, the voltage may be 300 V or less.

【0161】

As described above, the electrostatic suction type fluid discharge device according to the present embodiment is based on the newly proposed discharge model focusing on the local electric field strength, and therefore has a fine nozzle with a nozzle diameter of 0.01 μm to 25 μm. It is possible to control the discharge of the discharge fluid with a drive voltage of 1000 V or less. As a result of consideration based on the above model, a nozzle with a diameter of 25 μm or less has a drive voltage of 700 V or less, a nozzle with a diameter of 10 μm or less has a drive voltage of 500 V or less, and a nozzle with a diameter of 1 μm or less has a drive voltage of 1 μm or less. Is capable of discharge control with a drive voltage of 300V or less.

【0162】

In the electrostatic suction type fluid discharge device according to the present embodiment, as described above, both the nozzle diameter and the drive voltage can be reduced, but in this case, as compared with the conventional electrostatic suction type fluid discharge device. , The following tendencies become prominent.

【0163】

That is, in the case of the electrostatic suction type fluid discharge device as described above, the discharge characteristics basically depend on the electric resistance value in the discharge fluid flow path from the drive electrode to the nozzle tip inside the fluid discharge head. It is determined, and the lower the electric resistance value, the better the discharge responsiveness. That is, by lowering the electric resistance value in the discharge fluid flow path, the drive frequency can be improved, and further, the discharge fluid material having higher resistance can be discharged, and the range of selection of the discharge fluid material is widened. be able to.

【0164】

In order to lower the electric resistance value, it is effective to shorten the distance between the drive electrode and the tip of the nozzle.

【0165】

[Embodiment 1]

An embodiment of the present invention will be described below with reference to FIGS. 7 to 12.

【0166】

(Nozzle plate) FIG. 7 (a) is a perspective view of a part of the nozzle plate 8 of the present embodiment, and FIG. 7 (b) is a sectional view taken along line AA'of FIG. 7 (a). .. Two or more fluid discharge holes 9 are formed in the nozzle plate 8, and two fluid discharge holes 9 are shown in FIG. 7 (a). Further, FIG. 7 (c) is a perspective view of a part of the nozzle plate 8 observed from the fluid supply side.

【0167】

As shown in FIGS. 7A to 7C, the nozzle plate 8 has a first nozzle layer 1, a second nozzle layer 2, a first electrode layer 25, a second electrode layer 26, and a nozzle hole. (Nozzle hole) 11 is provided.

【0168】

The fluid discharge side surface of the first nozzle layer 1 forms the fluid discharge surface 8a of the nozzle plate 8 to form a liquid repellent layer 4, and the second nozzle layer is on the fluid supply side opposite to the fluid discharge surface 8a. 2 is arranged. Here, the first nozzle layer is formed to be very thin, for example, 1 to 8 μm thick, and the strength and rigidity of the nozzle plate 8 are ensured in the thick second nozzle layer 2. Here, the second nozzle layer 2 for ensuring strength and rigidity is set as one layer, but two or more layers may be used.

【0169】

The nozzle hole 11 is composed of a first nozzle hole 11a penetrating the first nozzle layer 1 and a second nozzle hole 11b penetrating the second nozzle layer 2. Here, the wall surface of the first nozzle hole 11a has a substantially cylindrical shape perpendicular to the fluid discharge surface 8a of the nozzle plate 8, and the substantially circular opening of the fluid discharge surface 8a on which the liquid repellent layer 4 is formed is a fluid. It becomes a discharge hole 9. On the other hand, the second nozzle hole 11b has a tapered shape (conical truncated cone shape) that expands from the opening on the side communicating with the first nozzle hole 11a, which has a cylindrical shape, to the hem, and the second nozzle layer 2 It passes through and is opened at the fluid supply surface 8b on the side opposite to the first nozzle layer 1. The substantially circular opening of the second nozzle hole 11b formed on the fluid supply surface 8b, which is also the surface of the second nozzle layer 2, becomes the fluid supply hole 12.

【0170】

A first electrode layer 25 is formed on substantially the entire inner wall of the first nozzle hole 11a and around the communication hole 11x in which the first nozzle hole 11a and the second nozzle hole 11b communicate with each other. The first electrode layer 25 is formed around a cylindrical portion 25a formed on substantially the entire inner wall of the nozzle hole 11a described above, and a communication hole 11x in which the first nozzle hole 11a and the second nozzle hole 11b communicate with each other. It consists of an extension portion 25b having a ring shape centered on the communication hole 11x. The extending portion 25b of these forms the upper bottom 11y of the truncated cone-shaped second nozzle hole 11b. That is, assuming that the diameter of the communication hole 11x (substantially circular) between the first nozzle hole 11a and the second nozzle hole 11b is D1, D1 is the upper bottom (opening on the fluid discharge side) 11y of the second nozzle hole 11b. Smaller than the caliber D2. The outer diameter D3 of the extending portion 25b of the first electrode layer 25 having a ring shape is larger than the diameter D2.

【0171】

Further, a second electrode layer 26 electrically connected to the first electrode layer 25 is formed on the inner wall of the second nozzle hole 11b. A part of the second electrode layer 26 is also arranged on the fluid supply surface 8b of the nozzle plate 8, and a part of the second electrode layer 26 has a lead-out wiring 26a as shown in FIG. 7 (c), and a discharge signal voltage is formed. It is connected to an application means (not shown).

【0172】

In FIGS. 7 (a) and 7 (c), in order to simplify the drawing, the first nozzle holes 11a and the second nozzle holes 11b formed in the nozzle holes 11 are formed on the inner walls of the first nozzle holes 11b. The electrode layer 25 and the second electrode layer 26 of the above are omitted.

【0173】

Specific examples of the size and material of each part will be described below, but the present invention is not limited to the specific examples.

【0174】

A polyimide film having a thickness of about 1 μm is used for the first nozzle layer 1, and a polyimide film having a thickness of about 20 μm is used for the second nozzle layer 2. The first electrode layer 25 has a thickness of 0.5 μm and is made of a metal material containing Ti as a main component, of which the cylindrical portion 25a is formed up to the fluid discharge side end in the inner wall of the first nozzle hole 11a. Has been done. On the other hand, the extension portion 25b has an outer diameter D3 of about 20 μm. If the electrode layer or the like formed at the interface between the first nozzle layer 1 and the second nozzle layer 2 is formed over the entire interface, it causes warpage due to the stress of the entire nozzle plate. In such a configuration in which the extension portion 25b is partially provided for each nozzle hole 11, warpage due to such stress can be reduced.

【0175】

On the other hand, the second electrode layer 26 has a thickness of 0.5 μm and is also made of a metal containing Ti as a main component. Then, as shown in FIG. 8, the connecting portion 26b of the second electrode layer 26 with the first electrode layer 25 is in surface contact with the extending portion 25b of the first electrode layer 25, and has a high connection. The reliability is ensured.

【0176】

The diameter of the opening that becomes the fluid discharge hole 9 in the first nozzle hole 11a is about 3 μm, and the first electrode layer 25 having a thickness of 0.5 μm is formed therein, so that the actual fluid discharge hole 9 is actually formed. The diameter (diameter) is about 2 μm. The diameter D2 of the upper base 11y of the second nozzle hole 11b is 10 μm, and the diameter of the opening serving as the fluid supply hole 12 is 30 μm.

【0177】

In the nozzle plate 8 having this configuration, it is desirable that the fluid discharge hole 9 is φ10 μm or less, and more preferably φ8 μm or less, in order to enable the discharge of ultratrace fluid and to form fine dots. By setting such a nozzle hole diameter (diameter), the formation of an electric field required over a wide range can be narrowed, and the voltage required for charge transfer, that is, the amount of charge required for electrostatically attracting a fluid. It is possible to significantly reduce the voltage required to apply the above to the fluid. According to this, since a high voltage such as 2000V is not required as in the conventional case, it is possible to improve the safety when using the fluid jet device.

【0178】

In particular, when the diameter is set to φ8 μm or less, the electric field strength distribution is effectively concentrated near the discharge surface of the fluid discharge hole, and the fluctuation of the distance from the counter electrode to the fluid protrusion hole of the nozzle affects the electric field strength distribution. Is gone. As a result, more stable fluid discharge can be performed without being affected by the position accuracy of the counter electrode, the material characteristics of the recording medium, and the thickness variation.

【0179】

Further, as described above, since the electric field strength distribution can be concentrated in the vicinity of the discharge surface of the fluid discharge hole 9, it is possible to form a strong electric field in a narrow region, and as a result, the amount of fluid that can be discharged is made ultratrace. It becomes possible. This makes it possible to increase the resolution of the printed image when the fluid is ink.

【0180】

The liquid-repellent layer 4 on the first nozzle layer 1 is formed of a fluorine-polymerized or silicon-based polymer film having a thickness of about 0.05 μm. The liquid-repellent layer 4 removes an excess region that wraps around the fluid discharge hole 9 by dry etching, as will be described later.

【0181】

According to the present embodiment, the shape of the fluid discharge hole 9 of the nozzle plate 8 which has a great influence on the landing accuracy is determined by the processing accuracy of the 1 μm polyimide film, so that the processing accuracy of the fluid discharge hole 9 is very high. It is very high, and it is possible to secure a very high landing accuracy accordingly.

【0182】

Further, in order to improve the machining accuracy of the fluid discharge hole 9, further higher machining accuracy can be obtained by reducing the film thickness of the first nozzle layer 1 exposed on the fluid discharge surface of the nozzle plate 8. .. At this time, by reducing the film thickness of the first nozzle layer 1, the rigidity of the first nozzle layer 1 is reduced and the structural reliability of the fluid discharge hole 9 is reduced, but the first nozzle layer is reduced. By arranging the second nozzle layer 2 in contact with 1, the first nozzle layer 1 is reinforced, and the shape accuracy of the fluid discharge hole 9 is improved without deteriorating the structural reliability of the first nozzle layer 1. Can be improved. That is, when producing a nozzle plate 8 having a fine fluid discharge hole 9, such a configuration is desirable.

【0183】

Further, since the first electrode layer 25 is locally provided at each position where the nozzle hole 11 is formed, it is electrically insulated from the first electrode layer 25 arranged in the adjacent nozzle hole 11. .. Therefore, the discharge signal can be applied independently to each channel, and there is little crosstalk, which can improve the resolution of the drawn image.

【0184】

Further, since the second nozzle hole 11b has a tapered shape, turbulence of the fluid is less likely to occur inside the second nozzle hole 11b, the fluid discharge stability can be improved, and the nozzle hole 11b can be improved. Since the edge between the inner wall and the fluid supply surface 8b is loosened, it is possible to effectively suppress the disconnection of the second electrode layer 26 extending to the fluid supply surface 8b. Further, the liquid repellent layer 4 formed on the fluid discharge surface 8a of the nozzle plate 8 can prevent the fluid from adhering to the vicinity of the fluid discharge hole 9.

【0185】

The material used for the first electrode layer 25 is not limited to a metal material containing Ti as a main component. During the etching process of the second nozzle layer 2 and the etching of the sacrificial layer 5 and the liquid repellent layer 4 that wraps around in the fluid discharge hole 9, which will be described later, a material having high resistance to the etching, that is, an etching gas ( Any material may be used as long as it is a material having high resistance to oxygen-containing plasma, fluorine-containing plasma, etc.) or etching (nitric acid, potassium hydroxide aqueous solution, etc.). Specific examples thereof include metal materials containing Ti, Al, Cu, Co, Fe, Ni, Au, Pt, Ta, W, Nb and the like as main components, and the metal material should be selected in combination with the above etching gas or etchant. Can be done.

【0186】

Similarly, the material used for the second electrode layer 26 is not limited to the metal material containing Ti as a main component. When etching the sacrificial layer 5 and the liquid-repellent layer 4 that wraps around the fluid discharge hole 9, which will be described later, a material having high resistance to the etching, that is, an etching gas (plasma containing oxygen and fluorine) is contained. Any material with high resistance to etching (plasma, etc.) or etching (nitric acid, potassium hydroxide aqueous solution, etc.) may be used. Specific examples thereof include metal materials containing Ti, Al, Cu, Co, Fe, Ni, Au, Pt, Ta, W, Nb and the like as main components, and the metal material should be selected in combination with the above etching gas or etchant. Can be done.

【0187】

Further, the material used for the first nozzle layer 1 is not limited to polyimide. It may be a polymer organic material other than polyimide, or SiO.₂, Si₃N₄It may be a Si compound material such as Si, or Si.

【0188】

The material used for the second nozzle layer 2 is not limited to polyimide. Similar to the first nozzle layer 1, it may be a polymer organic material other than polyimide, or SiO.₂, Si₃N₄It may be a Si compound material such as Si, or Si.

【0189】

Further, in the present embodiment, the second nozzle hole 11b has a truncated cone shape (tapered shape) narrowed at a portion communicating with the first nozzle hole 11a, but is not limited thereto. For example, as in the nozzle plate 8'shown in FIG. 9, the inner wall of the second nozzle hole 11b'has a so-called straight shape (cylindrical shape) perpendicular to the fluid discharge surface 8a and the fluid supply surface 8b of the nozzle plate 8'. It can also be formed.

【0190】

In this case, the fluid supply hole 12'of the second nozzle hole 11b'is smaller than the fluid supply hole 12 in which the second nozzle hole 11b shown in FIGS. 7 (a) to 7 (c) has a truncated cone shape. It is possible to further increase the degree of integration of the nozzles. Further, as shown in FIG. 7 (b), in the case of the nozzle plate 8, the second electrode layer 26 was formed only on one side surface of the inner wall of the second nozzle hole 11b due to its manufacturing convenience. As shown in FIG. 9, it may be formed on the entire surface of the inner wall of the second nozzle hole 11b.

【0191】

By using the nozzle plate 8 (8') having the configuration as in this embodiment, the following actions of (1) to (5) are exhibited. (1) Even if the fluid discharge hole 9 is a fine nozzle plate 8 (8') with a diameter of 8 μm or less, a structurally stable electrode capable of applying a discharge signal voltage to the tip of the nozzle hole 11 is formed. be able to. 2 On the fluid supply side of the second nozzle layer 2, the second electrode layer 26 is separated so that the adjacent channels are not electrically short-circuited, so that discharge signals can be easily sent independently to each channel. It can be applied, and there is little crosstalk, which can improve the resolution of the drawn image. 3 Since the rigidity of the nozzle plate 8 (8') can be maintained by the second nozzle layer 2, the rigidity of the entire nozzle plate 8 (8') becomes high and it becomes easy to handle. 4 Even if the processing accuracy of the second nozzle hole 11b processed into the thick second nozzle layer 2 is poor, the extension of the first electrode layer 25 during processing of the second nozzle hole 11b Since the etching stops at 25b, it does not affect the fluid discharge hole 9 that controls the fluid discharge amount. 5 The first electrode layer 25 is electrically connected to the second electrode layer 26 formed in the second nozzle hole 11b communicating with the first nozzle hole 11a, so that the second electrode is the second electrode. The drive signal can be supplied from the fluid supply side of the nozzle plate 8 via the layer 26, and the recording medium is electrically driven by the electric field generated from the lead wire 26b for supplying the drive signal to the first electrode layer 25. It will not be damaged.

【0192】

(Manufacturing Method of Nozzle Plate) Next, one manufacturing method of the nozzle plate 8 according to the present embodiment will be described. 10 (a) to 10 (i) are diagrams for explaining the manufacturing process of the nozzle plate 8.

【0193】

First, a sacrificial layer 5 is formed by wet plating (plating) using Ni on a substrate 6 made of Si, glass, or the like for temporary holding of an arbitrary thickness. Further, a polyimide resin is applied onto the sacrificial layer 5 by spin coating and fired at 350 ° C. for 2 hours to form the first nozzle layer 1. Here, the thickness of the sacrificial layer 5 was set to 10 μm, and the thickness of the first nozzle layer was set to 1 μm.

【0194】

Next, the opening pattern of the first nozzle hole 11a is formed on the first nozzle layer 1 with a photoresist, and the first nozzle hole 11a is formed by dry etching using a gas containing oxygen as a main component. Process (see Fig. 3 (a)).

【0195】

With this etching method, organic substances such as polyimide resin can be processed at high speed and with high accuracy, and the etching selectivity with Ni, which is the sacrificial layer 5, is high (Ni is hardly etched). Therefore, the sacrificial layer 5 is not significantly damaged by the above processing, and the flatness of the surface of the sacrificial layer 5 is maintained, so that the flatness of the fluid discharge surface of the nozzle plate 8 to be formed on the surface of the sacrificial layer 5 is maintained. The sex does not deteriorate. In addition, since this processing is performed with extremely high accuracy, etching conditions with high anisotropy are used. Further, since the first nozzle layer 1 is as thin as 1 μm as described above, the first nozzle hole 11a for discharging an ultratrace amount of fluid can be machined with high accuracy.

【0196】

Next, a first electrode layer 25 made of a metal material containing Ti as a main component is formed on the first nozzle layer 1 in which the first nozzle hole 11a is processed by a sputtering method. Further, a resist pattern 27 having a shape corresponding to the nozzle hole opening is formed on the first electrode layer 25 (see FIG. 3 (b)). Here, since the first electrode layer 25 needs to be formed on the inner wall of the first nozzle hole 11a, in order to improve the step coverage of the first electrode layer 25, under Ar gas pressure condition of 30 mTorr. , The film was formed so that the film thickness on the first nozzle layer 1 was 0.5 μm.

【0197】

Next, by dry etching with plasma using a gas containing Ar as a main component, the first electrode layer 25 is placed on the first nozzle layer 1 to form the above-mentioned extending portion 25b having a diameter of about 20 μm. The resist is removed by processing so that the residue remains (see Fig. 3 (c)). In this processing step, while suppressing damage to the first electrode layer 25 (cylindrical portion 25a) formed on the inner wall of the first nozzle hole 11a, on the sacrificial layer 5 which is the bottom of the first nozzle hole 11a. In order to remove the first electrode layer 25 formed on the surface, etching conditions with high anisotropy were adopted.

【0198】

The extending portion 25b partially left on the first electrode layer 1 has a substantially circular shape here, but it does not have to have a substantially circular shape in the processing process, and as will be described later, the first The upper bottom 11y of the nozzle hole 11b of 2 may have a shape that is arranged in the extension portion 25b formed so as to extend from the first nozzle hole 11a on the first nozzle layer 1.

【0199】

However, this nozzle plate is a nozzle plate 8 applied to an electrostatic suction type fluid discharge device, and since a discharge signal is applied to the nozzle tip portion via the first electrode layer 25, the first electrode layer 25 The electric field is concentrated not only on the tip of the nozzle but also on the end of the shape on the first nozzle layer 1. Therefore, in order to make the electric field concentrated on the end of the extension 25b on the first nozzle layer 1 uniform, the shape of the extension 25b should be processed into a highly isotropic shape close to a circle. Is desirable.

【0200】

Next, the second nozzle layer 2 is formed on the first nozzle layer 1 and the first electrode layer 25 with a thickness of 20 μm (see FIG. 3 (d)). The second nozzle layer 2 was coated with a coating type polyimide resin by a spin coating method in the same manner as the first nozzle layer 1 and fired at 350 ° C. for 2 hours to a thickness of 20 μm. Here, the first nozzle hole 11a is also filled with the polyimide resin. The second nozzle layer 2 is formed for the purpose of reinforcing the first nozzle layer 1 having a thin film thickness processed with high precision, and has an effect of increasing the rigidity of the entire nozzle plate 8.

【0201】

Next, a resist pattern 28 is formed on the second nozzle layer 2 by photolithography, dry etching is performed using a gas containing oxygen as a main component, and a truncated cone-shaped second is formed on the second nozzle layer 2. Nozzle hole 11b is formed (see Fig. 3 (e)). The dry etching can be stopped by the extending portion 25a of the first electrode layer 25 formed on the first nozzle layer 1. That is, the first nozzle layer 1 formed of a metal material containing Ti as a main component is hardly etched by dry etching using a gas containing oxygen as a main component, so that the first electrode layer 25 is exposed. At the site, dry etching does not proceed any further, and the second nozzle layer 2 that filled the first nozzle hole 11a in the previous step can be easily removed. Further, in the processing of the second nozzle hole 11b, the upper bottom 11y of the second nozzle hole 11b is placed in the extending portion 25b of the first electrode layer 25 at the joint with the first nozzle layer 1. Patterned to be placed.

【0202】

When processing the tapered shape of the second nozzle hole 11b, the etch rate of the resist pattern 28 and the polyimide resin of the second nozzle layer 2 are made substantially equal in the above etching, and the resist pattern 28 is set to 150 ° C. The resist pattern 28 was made into a tapered shape by post-baking for 60 minutes, and this shape was transferred to the second nozzle layer 2 by etching.

【0203】

That is, as shown in FIG. 11A, a resist pattern 28 having an etch rate substantially equal to that of the polyimide resin constituting the second nozzle layer 2 and having a tapered wall surface 28A is formed, and the second nozzle layer 2 is etched. Etch the resist pattern 28 at the same speed as, and widen the edge of the resist pattern 28. At this time, as shown in FIG. 11 (b), the second nozzle layer 2 is also etched at the same time, and as a result, the second nozzle layer 2 is subjected to as shown in FIG. 11 (c). A second nozzle hole 11b having the same shape as the tapered wall surface 28A formed in the resist pattern 28 is formed. Further, in this case, since the resist pattern 28 and the etch rate of the second nozzle layer 2 are substantially equal, it is desirable that the thickness of the resist pattern 28 is formed to be thicker than the thickness of the second nozzle layer 2. In FIG. 11, the description of the first nozzle hole 11a formed in the first nozzle layer 1 is omitted.

【0204】

Next, a second electrode layer 26 made of a metal material containing Ti as a main component is formed on the second nozzle layer 2. Here, using the ion beam sputtering method, the substrate is tilted so that the Ti particles fly from the direction of arrow K while suppressing the scattering of Ti particles by Ar atoms under an Ar gas pressure of 0.2 mTorr. The film was formed so that it was formed only on one side of the inner wall surface of the nozzle layer 2 and a part of the second electrode layer 26 was electrically short-circuited with the first electrode layer 25 (see FIG. 10 (f)). The film thickness is 0.5 μm.

【0205】

By forming the second electrode layer 26 while incident Ti particles from an oblique direction in this way, it is possible to prevent the second electrode layer 26 from adhering to the inside of the first nozzle hole 11a. As a result, it is possible to prevent the shape of the first nozzle hole 11a from changing or being blocked.

【0206】

Next, the photoresist pattern 29 is formed on the second electrode layer 26 so as to cover a part of the second nozzle hole 11b and the second electrode layer 26 formed on the second nozzle layer 2. Form (see Figure 10 (g)). The photoresist pattern 29 may be formed so as to cover a part of the second electrode layer 26 formed on the second nozzle hole 11b and the second nozzle layer 2, but in this embodiment, it may be formed. , The second electrode layer 26 formed on the second nozzle layer 2 has a shape that can be processed into a circular shape having a diameter of about 50 μm. Here, since the photoresist pattern 29 is formed so as to fill the second nozzle hole 11b, the thickness of the resist layer becomes very thick in the deepest region of the second nozzle hole 11b. Therefore, for the photoresist pattern 29, it is desirable to use a positive photoresist in which an unexposed portion remains as a pattern.

【0207】

At this time, it is desirable that the photoresist pattern 29 is used to form the lead-out wiring 26a on the second nozzle layer 2 by using the second electrode layer 26. In this case, since it is not necessary to create the lead-out wiring 26a in a separate process, the process can be simplified. Further, since the lead-out wiring 26a can be arranged on the opposite side of the recording medium via the nozzle plate 8 as described above, it is possible to keep a sufficient distance from the recording medium and the electric field generated from the lead-out wiring pattern. Does not cause fatal electrical damage to the recording medium.

【0208】

Next, based on the photoresist pattern 29, the second electrode layer 26 is processed by dry etching using plasma containing Ar gas as a main component, and the photoresist pattern 29 is removed (FIG. 10 (h)). reference). In this processing step, it is necessary to process the second electrode layer 26 into a desired shape, so etching was performed under etching conditions having high anisotropy. The photoresist pattern 29 was removed using a resist stripping solution.

【0209】

Next, after removing the photoresist pattern 29, the nozzle plate 8 is removed from the substrate 6 by immersing it in an aqueous solution containing nitric acid and water as main components and etching only the sacrificial layer 5 (FIG. 10 (i)). ). As described above, most of the polyimide resin forming the first nozzle layer 1 and the second nozzle layer 2 and the Ti forming the stopper layer 3 or the discharge hole layer 14 are produced by the etching solution of the sacrificial layer 5. Since it is not etched, the etching of the sacrificial layer 5 does not cause a change in shape or a decrease in structural reliability.

【0210】

Next, the liquid repellent layer 4 is formed on the surface of the first nozzle layer 1 from which the sacrificial layer 5 has been removed (FIG. 10 (i)). Here, a fluorine polymer is used for the purpose of considering the ease of application, and this is applied to the surface of the first nozzle layer 1 by a method such as stamping, and a liquid-repellent layer having a thickness of 0.05 μm is applied with a polymer film. Formed 4. The liquid repellent layer 4 that wraps around the first nozzle hole 11a is dry-etched from the second nozzle hole 11b side using oxygen-containing plasma after the liquid repellent layer 4 is formed. Was removed. As a result, damage to the nozzle plate 8 can be minimized.

【0211】

As described above, according to the present embodiment, each channel is attached to the nozzle plate 8 of the electrostatic suction type fluid discharge device that discharges an ultra-trace amount of fluid by performing photolithography and dry etching during the processing process. The first and second electrode layers 25 and 26 separated from each other can be accurately formed in the nozzle hole 11. As a result, the discharge signal can be applied independently to each channel, so that crosstalk is small, and the resolution of the drawn image can be improved.

【0212】

Further, since the first nozzle layer 1 can be formed thinly, the vicinity of the fluid discharge hole 9 is formed by controlling the gas pressure at the time of forming the first electrode layer 25 formed on the inner wall of the first nozzle hole 11a. It is possible to form a stable film. As a result, the electrical resistance R from the electrode to the tip of the nozzle is stabilized, and the discharge characteristics between the channels are stabilized.

【0213】

In the present embodiment, Ni is used as the sacrificial layer 5, polyimide resin is used as the first nozzle layer 1 and the second nozzle layer 2, and Ti is used as the first and second electrode layers 25 and 26. It is not limited to this combination.

【0214】

In addition to Ni, the sacrificial layer 5 contains Al, Cu, depending on the combination with the materials used for the first nozzle layer 1, the second nozzle layer 2, the first electrode layer 25, and the second electrode layer 26. A material soluble in nitric acid such as nitric acid or an aqueous solution of KOH, or a material that can be etched by oxygen plasma such as polyimide can be used. Further, as a method for forming the sacrificial layer 5, a vapor deposition method, a sputtering method, a coating method, or the like can be used in addition to plating, depending on the material.

【0215】

For the first nozzle layer 1, the second nozzle layer 2, and the second electrode layer 26, a material that is slightly damaged by etching of the sacrificial layer 5 can be used. Further, for the first electrode layer 25, a material having high resistance to the etching of the sacrificial layer 5 and the etching of the second nozzle hole 11b can be used.

【0216】

Here, in FIG. 12, the materials used (sacrificial layer, first nozzle layer, first electrode layer, second nozzle layer, second electrode layer) and processing method (first nozzle hole, first An example of a preferable combination of the electrode layer, the second nozzle hole, the second electrode layer, and the sacrificial layer removal) is shown.

【0217】

As shown in FIG. 12, the first nozzle layer 1 and the second nozzle layer 2 are not limited to polymer organic materials such as polyimide resin, and are Si or SiO.₂Inorganic silicon compounds such as can be selected. However, SiO₂In order to dry-etch or Si, it is necessary to use a reaction gas containing F, and Ti used in this embodiment has low resistance to this etching. It is desirable to use the material to be used as the first electrode layer 25 or the second electrode layer 26.

【0218】

Further, as the first electrode layer 25 or the second electrode layer 26, the materials shown in the same table can be used in addition to Ti, depending on the combination shown in FIG.

【0219】

Ti, which is the material of the first electrode layer 25, is CF.₄Even plasma using a mixed gas of oxygen and oxygen can be etched at a relatively high etching rate. However, the first nozzle layer 1 (polyimide) formed under Ti is etched at a higher speed than Ti by the plasma of the gas, and is greatly damaged. Therefore, in the present embodiment, a dry etching method using Ar ions is adopted for patterning the first electrode layer 25 and the second electrode layer 26.

【0220】

In this way, a dry etching method using Ar ions is adopted, in which the difference between the etch rate of the first electrode layer 25 or the second electrode layer 26 and the etch rate of the first nozzle layer 1 or the second nozzle layer 2 is small. By doing so, the first electrode layer 25 or the second electrode layer 26 can be patterned while minimizing the damage of the first nozzle layer 1 or the second nozzle layer 2.

【0221】

Further, in the present embodiment, the sacrificial layer 5 is completely removed by etching, but it is not necessary to completely remove the sacrificial layer 5, and only the portion of the sacrificial layer 5 in contact with the first nozzle layer 1 is removed. The nozzle plate 8 can be removed from the substrate 6 by removing it by etching.

【0222】

Further, the liquid repellent layer 4 is not limited to the fluorine polymer, and a silicon-based polymer film, DLC (diamond-like carbon) or the like can also be used.

【0223】

By using the above processing steps, it is possible to manufacture the nozzle plate 8 that exhibits the above-mentioned actions of (1) to (5).

【0224】

[Embodiment 2] Other embodiments of the present invention will be described below with reference to FIGS. 13 to 16. For convenience of explanation, members having the same functions as the members shown in the drawings of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

【0225】

(Nozzle plate) FIG. 13 (a) is a perspective view of a part of the nozzle plate 80 of the present embodiment, and FIG. 13 (b) is a sectional view taken along line B-B'of FIG. 13 (a). .. Two or more fluid discharge holes 9 are formed in the nozzle plate 80, and two fluid discharge holes 9 are shown in FIG. 13 (a). Further, FIG. 13 (c) is a perspective view of a part of the nozzle plate 80 observed from the fluid supply side.

【0226】

As shown in FIGS. 13 (a) to 13 (c), in the nozzle plate 80, the first nozzle hole 11c formed in the first nozzle layer 10 has a tapered shape like the second nozzle hole 11b. A surface electrode layer 81 is formed on the fluid discharge surface 80a of the nozzle plate 80 so as to close the opening on the fluid discharge side in the first nozzle hole 11c, and the penetration formed in the surface electrode layer 81 is formed. The hole 81a is a fluid discharge hole 9. The surface electrode layer 81 is electrically connected to the first electrode layer 25 formed on the inner wall of the first nozzle hole 11c, and the first electrode layer 25 and the second electrode layer 26 are formed. A drive signal can be applied from the fluid supply side of the nozzle plate 80 via the Here, too, the second nozzle layer 20 is one layer, but two or more layers may be used.

【0227】

Also in FIGS. 13 (a) and 13 (c), in order to simplify the drawing, the first first nozzle hole 11c and the second nozzle hole 11b formed in the nozzle hole 11 are formed on the inner walls. The electrode layer 25 and the second electrode layer 26 of the above are omitted.

【0228】

Specific examples of the size and material of each part will be described below, but the present invention is not limited to the specific examples.

【0229】

The surface electrode layer 81 is made of a metal material containing Pt as a main component, and is formed in a substantially circular shape having a diameter of 5 μm in order to reduce the stress of the entire nozzle plate 80. The thickness of the surface electrode layer 81 is 0.5 μm.

【0230】

The first nozzle layer 10 is SiO in this embodiment.₂It is made of an inorganic material whose main component is, and is formed to a thickness of 2 μm. The second nozzle layer 20 is made of an organic material containing a polyimide resin as a main component, and is formed to have a film thickness of 20 μm. A metal material containing Ti as a main component is used for the first electrode layer 25 and the second electrode layer 26, and the film thickness is 0.5 μm.

【0231】

The diameter of the fluid discharge hole 9 which is the through hole 81a formed in the surface electrode layer 81 is 2 μm, and the communication portion with the first nozzle hole 11c is processed perpendicular to the film surface. Here, the diameter of the fluid discharge hole 9 is preferably Φ10 μm or less, more preferably Φ8 μm or less, for the same reason as in the first embodiment.

【0232】

Further, the first nozzle hole 11c has a communication portion with the fluid discharge hole 9, that is, the fluid discharge side opening is processed to have a diameter of 4 μm, and the hem is widened to the communication portion with the second nozzle hole 11b. It is processed into a tapered shape (conical truncated cone shape) that opens.

【0233】

Further, the second nozzle hole 11b is processed to have a diameter of 20 μm at the communication portion with the first nozzle hole 11c, that is, the opening on the fluid discharge side, and has a tapered shape (conical truncated cone shape) that expands to the hem. It passes through the second nozzle layer 20 and opens at the fluid supply surface 80b of the nozzle plate 80.

【0234】

The upper bottom 11cy of the first nozzle hole 11c having a truncated cone shape has a ring shape centered substantially on the fluid discharge hole 9, and a part of the surface electrode layer 81 forms the upper bottom 11cy and is exposed. are doing. Therefore, the diameter of the communication hole 11cx (substantially circular) between the fluid discharge hole 9 and the first nozzle hole 11c is the outer diameter of the upper base 11cy of the first nozzle hole 11c (the first nozzle hole in the communication hole 11cx). 11c outer shape) smaller.

【0235】

Further, the upper bottom 11by of the truncated cone-shaped second nozzle hole 11b has a ring shape centered substantially on the first nozzle hole 11c, and a part of the first electrode layer forms the upper bottom 11by. And exposed. Therefore, the diameter of the communication hole 11bx (substantially circular) of the first nozzle hole 11c and the second nozzle hole 11b is the outer diameter of the upper bottom 11by of the second nozzle hole 11b (the second nozzle in the communication hole 11bx). Smaller than the outer shape of hole 11b).

【0236】

Further, in addition to at least a part of the inner wall of the first nozzle hole 11c, the first electrode layer 25 which becomes an extension portion 25b in the peripheral portion where the first nozzle hole 11c and the second nozzle hole 11b communicate with each other. Is formed. Here, SiO constituting the first nozzle layer 10₂Is highly resistant to dry etching by plasma containing oxygen due to the processing of the second nozzle hole 11b, which will be described later, so that the extension portion 25b of the first electrode layer 25 is not formed and the first nozzle layer Even when the 10 or the first nozzle hole 11c is exposed to the etching of the second nozzle hole 11b, the shape of the first nozzle hole 11c is not deformed with almost no etching.

【0237】

On the other hand, when a material having low resistance to etching in the processing of the second nozzle hole 11b is used for the first nozzle layer 10 (for example, as in the case of the first embodiment, the first nozzle layer 10 and the first nozzle layer 10 are used. It is desirable that the first electrode layer 25 be formed so as to cover the entire inner wall of the first nozzle hole 11c). That is, the first electrode layer 25 functions as a protective layer that protects the first nozzle hole 11c or the first nozzle layer 10 from the etching in the processing step of the second nozzle hole 11b.

【0238】

Further, a second electrode layer 26 electrically connected to the first electrode layer 25 is formed on the inner wall of the second nozzle hole 11b. A part of the second electrode layer 26 is also arranged on the fluid supply side surface of the second nozzle layer 20 forming the fluid supply surface 80b of the nozzle plate 80, as shown in FIG. 13 (c). In addition, a second electrode layer 26 formed on the surface thereof is processed and connected to a drive signal voltage applying means (not shown) by a wiring pattern 26a. The liquid repellent layer 4 is formed of a polymer material having a fluorine polymer having a thickness of 0.05 μm.

【0239】

Further, since the surface electrode layer 81 has high resistance to the etching means of the first nozzle hole 11c, the shape of the fluid discharge hole 9 is not deformed by the etching of the first nozzle hole 11ca. Further, since the shape of the fluid discharge hole 9 of the nozzle plate, which has a great influence on the landing accuracy, is determined by the processing accuracy of the above 0.5 μm Ti film that becomes the surface electrode layer 81, the processing accuracy of the fluid discharge hole 9 is very high. It is high, and it is possible to secure a very high landing accuracy accordingly.

【0240】

By the way, in order to improve the processing accuracy of the fluid discharge hole 9, further higher processing accuracy can be obtained by reducing the film thickness of the surface electrode layer 81, but by reducing the film thickness of the surface electrode layer 81, , The rigidity of the surface electrode layer 81 is reduced, and the structural reliability of the fluid discharge hole 9 is reduced.

【0241】

However, by arranging the first nozzle layer 10 in contact with the surface electrode layer 81 in this way, the surface electrode layer 81 is reinforced and the fluid discharge hole is not deteriorated in the structural reliability of the surface electrode layer 81. The shape accuracy of 9 can be improved.

【0242】

Further, since the first electrode layer 25 has high resistance to the etching means of the second nozzle hole 11b, the shape of the first nozzle hole 11c is significantly increased by processing the second nozzle hole 11b. The first nozzle layer 10 is not completely removed by the overetching of the processing of the second nozzle hole 11b.

【0243】

The material used for the surface electrode layer 81 is not limited to the metal material containing Pt as a main component. Higher than the etching of the first nozzle hole 11c, the second nozzle hole 11b, the sacrificial layer 50 described later, and the liquid repellent layer 4 wrapping around in the fluid discharge hole 9. Any material having resistance, that is, a material having high resistance to fluorine-containing plasma, oxygen-containing plasma, nitric acid, potassium hydroxide aqueous solution, etc., may be used, and sacrificial layer etching, first nozzle hole processing, second nozzle hole processing, second It can be used in combination with the nozzle hole processing method. Specific examples thereof include metal materials containing Al, Cu, Co, Fe, Ni, Au, Pt, etc. as main components, which can be selected in combination with the above etching gas or etchant.

【0244】

In addition, the materials such as the first nozzle layer 10, the first nozzle layer 2, the first electrode layer 25, and the second electrode layer 26 are not limited to the above, and are suitable for the materials and the manufacturing method. The combination will be described later.

【0245】

Further, in the present embodiment, the second nozzle hole 11b has a truncated cone shape (tapered shape) in which the communicating portion 11bx with the first nozzle hole 11c is narrowed, but the present invention is not limited to this. For example, as in the nozzle plate 80'of the modified example shown in FIG. 14, the side wall of the second nozzle hole 11b can be formed in a so-called straight shape (cylindrical shape) perpendicular to the stopper layer 3. In this case, the fluid supply hole 12 of the second nozzle hole 11b can be made smaller, and the degree of nozzle integration can be further increased. Further, as shown in FIG. 14, the second electrode layer 26 may be formed on the entire inner wall surface of the second nozzle hole 11b, and in this case, the reliability of the electric conduction of the second electrode layer 26 is improved. To do.

【0246】

Further, here, one through hole 81a is formed for one surface electrode layer 81 corresponding to one nozzle hole 11, but a plurality of through holes are formed in one surface electrode layer 81. A plurality of fluid discharge holes 9 may be provided for one nozzle hole 11.

【0247】

Further, the first nozzle hole 11c can be formed in a so-called straight shape (cylindrical shape) in which the side wall is perpendicular to the nozzle plate surface, as in the case of the nozzle plate 8 of the embodiment. In this case, since the processing accuracy of the first nozzle hole is improved, the shape of the surface electrode layer 81 can be reduced, and the stress generated by the surface electrode layer 81 can be reduced.

【0248】

By using the nozzle plate 80 (80') having the configuration as in the present embodiment, the following actions are performed in addition to the above-mentioned 1 to 5 . (6) Since the first nozzle hole 11c is formed in a tapered shape, the coverage of the first electrode layer 25 formed in the first nozzle hole 11c is good, and the reliability of conductivity is improved. 7 Since the through hole 81a formed in the surface electrode layer 81 of the thin film becomes the hole fluid discharge hole 9, the processing accuracy is very high, and the shape of the fluid discharge hole 9 by forming the first electrode layer 25. Since there is no change, discharge reliability is improved.

【0249】

(Manufacturing Method of Nozzle Plate) Next, one manufacturing method of the nozzle plate 80 according to the present embodiment will be described. 15 (a) to 15 (g) are views for explaining the manufacturing process of the nozzle plate 80.

【0250】

First, the sacrificial layer 50 is formed on the substrate 6 in the same manner as in the first embodiment (FIG. 15 (a)). Here, the thickness of the sacrificial layer 50 is 10 μm. Further, a Pt film having a thickness of 0.5 μm is formed on the sacrificial layer 50 by a method such as vapor deposition, and the outer shape is such that the surface electrode layer 81 is partially formed in the nozzle hole 11 forming portion by using photolithography. A resist pattern having a shape and a through hole 81 that serves as a fluid discharge hole 9 is formed. After that, the outer shape of the surface electrode layer 81 and the fluid discharge hole 9 are processed at the same time by using a dry etching method.

【0251】

Since the Pt film is a chemically relatively inert material, the dry etching here uses sputter etching using Ar, and is processed by a method in which physical processing is dominant. In addition, since this processing is performed with extremely high accuracy, etching conditions with high anisotropy are used. Here, the shape of the surface electrode layer 81 is processed into a substantially circular shape having a diameter of 5 μm. Further, the fluid discharge hole 9 arranged inside the surface electrode layer 81 is formed in a substantially circular shape having a diameter of 2 μm.

【0252】

Next, SiO is placed on the sacrificial layer 50 and the surface electrode layer 81.₂The first nozzle layer 10 made of a film is formed by the P-CVD method. According to this P-CVD method, SiO is formed.₂The stress of the film can be controlled by the composition of the gas used for film formation, the gas pressure, and the RF power for generating plasma, and since the stepped portion has a good circumference, the stepped portion of the surface electrode layer 81 is described. There are no cracks or the like in the part, and the structural reliability of the film is high. Therefore, the structural reliability of the entire nozzle plate is increased (see FIG. 15 (a)).

【0253】

Next, a resist pattern is created on the first nozzle layer 10 by photolithography, processed by reactive ion etching (RIE) containing fluorine gas and oxygen gas, and after processing, the resist is removed by a resist stripping solution. To do. (See Figure 15 (b)). In this etching method, fluorine activated by plasma selectively reacts with Si atoms, so SiO₂Etching rate is very high. On the other hand, as described above, since Pt is a chemically stable material, it hardly reacts with the activated fluorine. Therefore, the etching rate of Pt is slow, so that this etching can be accurately stopped at the interface between the surface electrode layer 81 and the first nozzle layer 10.

【0254】

In addition, in this processing process, SiO is used by using plasma containing fluorine gas and oxygen gas.₂And the etching rate of the photoresist is set to the same level, and SiO is used using the method that reflects the shape of the resist used in the step of processing the second nozzle layer 20 of the first embodiment.₂The first nozzle hole 11c was machined into a tapered shape. Here, the shape of the first nozzle hole 11c that can be placed at the joint with the surface electrode layer 81 is a substantially circular shape with a diameter of 4 μm, and the opening diameter at the interface with the second nozzle layer 20 is 6 μm. Further, the shape of the first nozzle hole 11c is larger than that of the fluid discharge hole 9, and the fluid discharge hole 9 is processed so as to be arranged in the pattern of the first nozzle hole 11c.

【0255】

Further, since the first nozzle hole 11c may be joined to the surface electrode layer 81, not only a tapered shape but also a so-called straight shape perpendicular to the nozzle surface may be used.

【0256】

Next, Ti is formed from the direction of arrow K1 (18 ° with respect to the surface of the first nozzle layer 10) by ion beam sputtering, and the surface electrode layer 81, a part of the first nozzle hole 11c, and the first A first electrode layer 25 having a thickness of 0.5 μm is formed on the nozzle layer 10 of 1. At this time, the shape of the first nozzle hole 11c and the thickness of the first nozzle layer 10 are taken into consideration so that the Ti film is not formed inside the fluid discharge hole 9 formed in the surface electrode layer 81. It is desirable to determine the incident direction of Ti particles. Further, here, the substrate is fixed to form the first electrode layer 25, but after setting the incident angle, the substrate is rotated around the normal direction of the nozzle surface to form the first nozzle hole. The first electrode layer 25 can be formed on the entire surface of the 11c side wall. The first electrode layer 25 adhering to the entire surface of the side wall of the first nozzle hole formed in this way can function as a protective layer for the first nozzle hole 11c during the processing of the second nozzle hole, which will be described later. ..

【0257】

Next, the outer shape of the first electrode layer 25 on the first nozzle layer 10 is processed by using a dry etching method. In this processing, the processing method implemented when processing the second electrode layer 26 in the first embodiment was used. That is, after forming a desired pattern with a positive photoresist, processing was performed by dry etching using plasma containing Ar gas as a main component. Here, the shape of the first electrode layer 25 arranged at the interface between the first nozzle layer 10 and the second nozzle layer 20 is a substantially circular shape having a diameter of 16 μm (see FIG. 15 (c)).

【0258】

Next, a coating-type polyimide resin having a thickness of 20 μm is formed on the first nozzle layer 10 to form a second nozzle layer 20 (see FIG. 15 (d)). Here, the coating type polyimide resin was applied onto the first nozzle layer 10 by spin coating and fired at 350 ° C. for 2 hours. Here, the fluid discharge hole 9 and the first nozzle hole 11c are also filled with the polyimide resin.

【0259】

Next, a resist pattern 70 is formed on the second nozzle layer 20 by photolithography, dry etching is performed using a gas containing oxygen as a main component, and the second nozzle layer 20 has a tapered shape (truncated cone shape). ), A second nozzle hole 11b was formed (see FIG. 15 (e)).

【0260】

The dry etching can be stopped by the first nozzle layer 10, the first electrode layer 25, or the surface electrode layer 81. That is, dry etching does not proceed any further at the portion where the first nozzle layer 10 or the first electrode layer 25 is exposed except for the first nozzle hole 11c. Similarly, dry etching does not proceed any further at the portion where the surface electrode layer 81 is exposed except for the fluid discharge hole 9 of the surface electrode layer 81. That is, in the processing process of the second nozzle hole 11b, the first nozzle hole 11c and the fluid discharge hole 9 filled with the polyimide resin in the previous step are reproduced by removing the polyimide resin, and the fluid. The second nozzle layer 20 material existing in the shape determined by the pattern formed on the surface electrode layer 81 is removed from the discharge hole 9, and the shape filled with the polyimide resin in the previous step is reproduced.

【0261】

Next, the resist pattern 70 is removed using a resist stripping solution, and a second electrode layer 26 made of a metal material containing Ti as a main component is formed on the second nozzle layer 20. Here, using the ion beam sputtering method, the substrate is tilted so that the Ti particles fly from the direction of the arrow K2 while suppressing the scattering of the Ti particles by the Ar atoms under the Ar gas pressure of 0.2 mTorr. The film was formed on only one side of the inner wall surface of the nozzle layer 20 of the above, and a part of the second electrode layer 26 was formed so as to be electrically short-circuited with the first electrode layer 25 (see FIG. 15 (f)). The film thickness is 0.5 μm. By forming the second electrode layer 26 while incident Ti particles from an oblique direction in this way, it is possible to prevent the second electrode layer 26 from adhering to the fluid discharge hole 9. , It is possible to prevent the shape of the fluid discharge hole 9 from changing or being blocked.

【0262】

Next, the second electrode layer 26 is processed, but this step is the same as that of the first embodiment and is omitted. The shape of the second electrode layer 26 formed on the second nozzle layer was a circular shape having a diameter of about 70 μm.

【0263】

Next, the nozzle plate 80 is removed from the substrate 6 by immersing it in an aqueous solution containing nitric acid and water as main components and etching only the sacrificial layer 50 (FIG. 15 (g)). As described above, SiO forming the first nozzle layer 10₂, The polyimide resin forming the second nozzle layer 20, Pt forming the surface electrode layer 81, and Ti forming the first electrode layer 25 and the second electrode layer 26 are determined by the etching solution of the sacrificial layer 50. Since it is hardly etched, the etching of the sacrificial layer 50 does not cause a change in shape or a decrease in structural reliability.

【0264】

Next, the liquid repellent layer 4 is formed on the surface of the first nozzle layer 10 (FIG. 15 (g)). Here, a fluorine polymer was used for the purpose of considering the ease of coating, and this was coated on the surface of the first nozzle layer 10 by a method such as stamping to form a liquid repellent layer 4 with a polymer film. The liquid-repellent layer that wraps around the first nozzle hole 11c is removed by dry etching from the second nozzle hole 11b side using oxygen-containing plasma after the liquid-repellent layer is formed. did. As a result, damage to the nozzle plate 80 can be minimized.

【0265】

In the actual form, the wraparound is removed by etching by dry etching using a plasma containing oxygen. However, in the actual embodiment, as described above, there is a surface electrode layer 81 having high resistance to dry etching using plasma containing oxygen on the fluid discharge surface, and the surface electrode layer 81 is Since the shape of the fluid discharge hole 9 is determined, the shape of the fluid discharge hole 9 does not change due to the above dry etching. Therefore, it is possible to form a nozzle hole with extremely high accuracy.

【0266】

Specifically, when the shape of each fluid discharge hole 9 of the nozzle plate 80 having 200 fluid discharge holes 9 created by using the process of the present embodiment was evaluated, the variation was as high as ± 0.15 μm. I was able to process it with precision. The warp of the nozzle plate 80 was also very flat, 10 μm or less.

【0267】

In this embodiment, the sacrificial layer 50 is Ni, the surface electrode layer 81 is Pt, and the first nozzle layer 10 is SiO.₂, Polyimide resin was used for the second nozzle layer 20, Ti was used for the first electrode layer 25, and Ti was used for the second electrode layer 26, but the combination is not limited to this.

【0268】

In addition to Ni, the sacrificial layer 50 can be made into nitric acid such as Al, Cu, or an aqueous KOH solution by combining with the materials used for the surface electrode layer 81, the first nozzle layer 10, and the second nozzle layer 20. Soluble materials can be used. Further, as a method for forming the sacrificial layer 50, a vapor deposition method, a sputtering method, a coating method, or the like can be used in addition to plating, depending on the material.

【0269】

For the second nozzle layer 20 and the second electrode layer 26, a material that is slightly damaged by etching of the sacrificial layer 50 can be used. However, considering the selectivity for etching with the first nozzle layer or the surface electrode layer 81, which will be described later, an organic resin capable of etching using oxygen-containing plasma is desirable. Further, when an organic resin having a molecular structure in which molecular chains are crosslinked with each other is used, the heat resistance and environmental resistance of the second nozzle layer 20 are high, and the reliability of the nozzle plate can be improved.

【0270】

Further, for the first nozzle layer 10 and the first electrode layer 25, a material having high resistance to the etching of the sacrificial layer 50 and the etching of the second nozzle hole 11b can be used. Further, for the surface electrode layer 81, a material having high resistance to the etching of the sacrificial layer 50, the etching of the second nozzle hole 11b, and the etching of the first nozzle hole 11c can be used.

【0271】

Here, in FIG. 16, the materials used (sacrificial layer, surface electrode layer, first nozzle layer, second nozzle layer, first electrode layer, first electrode layer forming region, second electrode layer) are shown. An example of a preferable combination of the fluid discharge hole, the first nozzle hole, the second nozzle hole, and the sacrificial layer removal is shown.

【0272】

As shown in FIG. 16, the first nozzle layer 10 or the second nozzle layer 20 is made of an organic resin such as polyimide or SiO.₂The nozzle layer can be formed by combining inorganic materials such as Si compounds as described above. However, for example, SiO₂/ SiO₂In the case of a combination such as a combination of, or a combination of polyimide / polyimide in which the first nozzle layer 10 is damaged during the processing of the second nozzle hole, the first electrode layer 25 is used as the first nozzle hole. It is necessary to form it on the entire inner wall of 11c to protect the first nozzle hole 11c.

【0273】

Further, in the present embodiment, the sacrificial layer 50 is completely removed by etching, but it is not necessary to completely remove the sacrificial layer 50, and only the portion of the sacrificial layer 50 in contact with the first nozzle layer 10 is removed. The nozzle plate 80 can be removed from the substrate 6 by removing it by etching.

【0274】

Further, the liquid repellent layer 4 is not limited to the fluorine polymer, and a silicon-based polymer film, DLC (diamond-like carbon) or the like can also be used.

【0275】

By using the above processing steps, it is possible to manufacture the nozzle plate 80 that exhibits the above-mentioned actions of (1) to (7).

【0276】

Further, through all the above-described embodiments, a configuration that does not form the liquid repellent layer 4 can be adopted. By not forming the liquid repellent layer 4 on the surface electrode layer 81 or the first nozzle layer 1, the shape accuracy of the fluid discharge hole 9 is further improved.

【0277】

Further, through all the above-described embodiments, it is composed of a plurality of thin films having a surface electrode layer 81, a first electrode layer 25, a second electrode layer 26, and a metal film containing the above-mentioned material as a main component. It may be a so-called laminated film.

【0278】

Further, in each of the above-described embodiments, a method of forming the sacrificial layers 5 and 50 on the substrate 6 and etching the sacrificial layers 5 and 50 to manufacture the nozzle plates 8 and 80 has been described. In addition, the first nozzle layers 1 and 10 can be directly formed on a substrate made of a material that can be etched by the same method as the etching of the sacrificial layers 5 and 50, such as a Ni plate. ..

【0279】

Finally, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the technical means disclosed in the different embodiments can be appropriately combined. The obtained embodiments are also included in the technical scope of the present invention.

【0280】

[Effect of the invention]

As described above, the nozzle plate of the present invention has a first nozzle hole and is laminated on the fluid supply side of the thin first nozzle layer arranged on the fluid discharge side and the first nozzle layer. A second nozzle layer that is thicker than the first nozzle layer and has a second nozzle hole that communicates with the first nozzle hole and forms a nozzle hole portion with the first nozzle hole. The first electrode layer formed on the inner wall of the first nozzle hole and the second electrode layer formed on the inner wall of the second nozzle hole are electrically connected to each other. It is characterized by being.

【0281】

With the above configuration, the first nozzle hole formed in the first nozzle layer can be formed into an ultrafine hole having a hole diameter of, for example, 10 μm or less, and the first nozzle hole is formed on the inner wall of such an ultrafine first nozzle hole. It is possible to form a stable film of the electrode layer 1 in the layer thickness direction, and when the opening of the first nozzle hole on the fluid discharge surface is a fluid discharge hole, the first one is close to the fluid discharge hole. The electrode can be formed into a film. As a result, the electric resistance R inside the nozzle can be dramatically reduced as compared with the conventional case, the discharge frequency of the fluid can be improved, and high-speed drawing on the recording medium becomes possible.

【0282】

Moreover, since the first electrode layer formed in this way is electrically connected to the second electrode layer formed in the second nozzle hole communicating with the first nozzle hole, the second electrode layer is second. A drive signal can be supplied from the fluid supply side of the nozzle plate via the electrode layer. Therefore, the lead-out wiring for supplying the drive signal to the first electrode layer does not come close to the medium, and the recording medium is not electrically damaged by the electric field generated from the lead-out wiring.

【0283】

Further, in the nozzle plate of the present invention, a surface electrode layer having a through hole is further arranged on the fluid discharge side of the first nozzle hole so as to close the fluid discharge side opening of the first nozzle hole. It can also be characterized in that the through hole and the first nozzle hole communicate with each other and the surface electrode layer is electrically connected to the first electrode layer.

【0284】

According to the above configuration, the through hole of the surface electrode layer provided on the fluid discharge surface of the nozzle plate becomes the fluid discharge hole, so that the fluid discharge hole that greatly affects the landing accuracy of the discharged fluid is etched by the surface electrode layer. Can be processed. As a result, the shape accuracy of the fluid discharge hole is dramatically stabilized as compared with the configuration in which the fluid discharge side opening of the first nozzle hole in which the first electrode layer is formed on the inner wall is used as the fluid discharge hole. Along with this, the landing accuracy can be further stabilized.

【0285】

As described above, the method for manufacturing the nozzle plate of the present invention includes a step of forming a sacrificial layer on the substrate, a step of forming a first nozzle layer on the sacrificial layer, and a plurality of steps on the first nozzle layer. The step of forming the first nozzle hole, the step of forming the first electrode layer on the first nozzle layer including the inner wall surface of each first nozzle hole, and the step of forming the first electrode layer on each first nozzle hole inner wall. The step of processing the first electrode layer so as to remain around each of the first nozzle holes, and the second step including each remaining first electrode layer portion on the first nozzle layer. A step of forming a nozzle layer and a plurality of second nozzle holes in the second nozzle layer, and each second nozzle hole having an opening on the fluid discharge side remaining on the first nozzle layer. A step of forming the second electrode layer so as to fit in the electrode layer portion of 1, a step of forming a second electrode layer on the second nozzle layer including the inner wall surface of each second nozzle hole, and a second adjacent second nozzle layer. It is characterized by including a step of processing the second electrode layer so as to be electrically separated between the nozzle holes.

【0286】

According to this, the first nozzle layer, the first electrode layer, the second nozzle layer, and the second electrode layer are sequentially laminated on the highly rigid substrate via the sacrificial layer. Therefore, after forming a resist pattern using photolithography technology, it can be processed into a desired shape by dry etching, so that the first nozzle hole, the second nozzle hole, the first electrode layer, and the second electrode layer can be processed. Can be formed with very high shape accuracy.

【0287】

Further, since the fluid discharge surface of the nozzle plate is protected by the sacrificial layer until the final stage of the process, there is no danger that the fluid discharge hole is damaged and the fluid discharge hole is deformed in the nozzle plate manufacturing process. Therefore, the manufacturing yield of the nozzle plate is improved.

【0288】

Further, in the method for manufacturing a nozzle plate of the present invention, a surface electrode layer is further formed on the sacrificial layer between the step of forming the sacrificial layer on the substrate and the step of forming the first nozzle layer on the sacrificial layer. In the step of forming the first nozzle layer on the sacrificial layer, which has a step of forming the surface electrode layer corresponding to the nozzle hole forming portion and forming a through hole in each separating portion. It can also be characterized by forming a first nozzle layer including on the separated surface electrode layer.

【0289】

In the method for manufacturing a nozzle plate having this configuration, since a fluid discharge hole can be formed as a through hole in the surface electrode layer formed on the sacrificial layer, the first electrode layer formed in the first nozzle hole can be formed. Due to the non-uniformity (for example, film thickness distribution), the shape of the fluid discharge hole is not deformed, and a nozzle plate having a highly accurate fluid discharge hole can be manufactured.

[Simple explanation of drawings]

FIG. 1 is a diagram for explaining the calculation of the electric field strength of the nozzle in the discharge model which is the basis of the present invention.

FIG. 2 is a graph showing model calculation results of nozzle diameter dependence of surface tension pressure and electrostatic pressure.

FIG. 3 is a graph showing a model calculation result of nozzle diameter dependence of discharge pressure.

FIG. 4 is a graph showing a model calculation result of nozzle diameter dependence of discharge limit voltage.

FIG. 5 is a graph showing the correlation between the mirror image force acting between the charged droplet and the substrate and the distance between the nozzle and the substrate.

FIG. 6 is a graph showing a model calculation result of the correlation between the flow rate flowing out from the nozzle and the applied voltage.

7 (a) and 7 (c) are perspective views showing a nozzle plate according to an embodiment of the present invention, and FIG. 7 (b) is a sectional view taken along line AA'of (a).

FIG. 8 is an explanatory view showing a connecting portion between the first electrode layer and the second electrode layer in the nozzle plate.

FIG. 9 shows a modified example of the nozzle plate according to the present embodiment, and is a cross-sectional view corresponding to FIG. 7 (c).

10 (a) to 10 (i) are explanatory views showing the manufacturing method of the nozzle plate of the present embodiment by the configuration of the cross section.

11 (a) to 11 (c) are explanatory views showing the steps shown in FIG. 10 (e) in detail by the configuration of the cross section of the nozzle plate.

FIG. 12 is an explanatory diagram showing a preferable combination of a material used for each layer and a processing method when manufacturing the nozzle plate according to the present embodiment.

13 (a) and 13 (c) are perspective views showing a nozzle plate according to another embodiment of the present invention, and FIG. 13 (b) is a sectional view taken along line B-B'of (a).

FIG. 14 shows a modified example of the nozzle plate according to another embodiment, and is a cross-sectional view corresponding to FIG. 13 (c).

15 (a) to 15 (g) are explanatory views showing a method of manufacturing the nozzle plate according to another embodiment by the configuration of a cross section.

FIG. 16 is an explanatory diagram showing a preferable combination of a material used for each layer and a processing method when manufacturing a nozzle plate according to another embodiment.

FIG. 17 is a schematic configuration sectional view of a conventional electrostatic suction type inkjet device.

18 (a) to 18 (c) are diagrams for explaining the behavior of the ink meniscus in the inkjet apparatus shown in FIG.

FIG. 19 is a schematic configuration diagram of another conventional electrostatic suction type inkjet device.

20 is a schematic cross-sectional perspective view of a nozzle portion of the inkjet device shown in FIG. 19. FIG.

FIG. 21 is a diagram illustrating an ink ejection principle of the inkjet device shown in FIG.

FIG. 22 is a diagram illustrating a state of fine particles when a voltage is applied to the nozzle portion of the inkjet device shown in FIG.

FIG. 23 is a diagram illustrating a principle of forming fine particles in a nozzle portion of the inkjet device shown in FIG.

24 (a) to 24 (c) are diagrams illustrating the behavior of the ink meniscus in the inkjet apparatus shown in FIG.

FIG. 25 (a) is a schematic configuration diagram of an electrostatic suction type fluid discharge device, and FIG. 25 (b) is an equivalent circuit thereof.

FIG. 26 is a side sectional view of a conventional nozzle plate used in an electrostatic suction type inkjet device.

FIG. 27 is a cross-sectional view showing a configuration of a recording head portion of a conventional electrostatic suction type inkjet device.

28 is a partially enlarged cross-sectional plan view showing an ink ejection hole in the recording head portion of the electrostatic suction type inkjet device of FIG. 28. FIG.

[Explanation of symbols]

1 1st nozzle layer 2 2nd nozzle layer 4 Liquid repellent film 5 Sacrificial layer 8 Nozzle plate 9 Fluid discharge hole 10 1st nozzle layer 11 Nozzle hole (nozzle hole) 11a 1st nozzle hole 11c 1st nozzle Hole 11b Second nozzle hole 20 Second nozzle layer 25 First electrode layer 25b Extended part (extended first electrode layer part) 26 Second electrode layer 50 Sacrificial layer 80 Nozzle plate 81 Surface electrode layer