Method for forming multi-layered structure, method for manufacturing wiring substrate, and method for manufacturing electronic apparatus

The present invention relates to a method for forming a multilayer structure using a droplet ejection device, and more particularly to a method for forming a multilayer structure suitable for manufacturing a wiring board or manufacturing an electronic device.

Attention is being paid to a method of manufacturing a wiring board or a circuit board by using an additive process by a printing method. This is because the cost of the additive process is lower than the method of manufacturing a wiring board or a circuit board by repeating the thin film coating process and the photolithography process.

As one of the techniques used for such an additive process, a technique for forming a conductive pattern by an inkjet method is known (for example, Patent Document 1).

<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2004-6578</text></patcit>

<p> When droplets of a resin material or a conductive material are arranged by using an inkjet method to provide an insulating layer and a wiring pattern on the insulating layer, the wiring pattern may be broken.</p><p> The present invention has been made in view of the above problems, and one of the objects thereof is to form a stable multilayer structure by using an inkjet method.</p>

<p> The multilayer structure forming method of the present invention uses a droplet ejection device. This multilayer structure forming method includes a step (A) of ejecting droplets of a first insulating material containing a first photosensitive resin onto an object surface to form a first insulating material layer covering the object surface, and the first step (A). 1 In the step (B) of curing the insulating material layer to obtain the first insulating layer, and ejecting droplets of the conductive material onto the first insulating layer, the conductive material layer is placed on the first insulating layer. It includes a step (C) of forming a pattern and a step (D) of activating the pattern of the conductive material layer to form a wiring pattern on the first insulating layer.</p><p> One of the effects obtained by the above configuration is that the wiring pattern is formed after the first insulating material layer is cured, so that the wiring pattern is not broken.</p><p> According to an aspect of the present invention, in the method for forming a multilayer structure, a step (E) of liquefying the surface of the first insulating layer and a second photosensitive resin are applied to the first insulating layer and the conductive layer. A step (F) of forming a second insulating material layer that covers the first insulating layer and the conductive layer by ejecting droplets of the containing second insulating material, and a step of curing the second insulating material layer (F). G) and further include.</p><p> According to the above configuration, since the surface of the first insulating layer is liquefied, a second insulating layer having a flat surface can be formed over the first insulating layer.</p><p> Preferably, the step (B) includes a step of irradiating the first insulating material layer with light of a first wavelength to cure the first insulating material layer. Then, the step (E) includes a step of irradiating the surface of the first insulating layer with light having a second wavelength different from the first wavelength to liquefy the surface of the first insulating layer. There is.</p><p> One of the effects obtained by the above configuration is that the curing of the first insulating material layer and the liquefaction of the first insulating layer can be achieved only by the step including light irradiation.</p><p> The multilayer structure forming method of the present invention uses a droplet ejection device. This multi-layer structure forming method includes a step (A) of ejecting droplets of a first insulating material containing a first photosensitive resin onto an object surface to form a first insulating material layer covering the object surface, and the first step (A). 1 The step (B) of curing the insulating material layer to obtain the first insulating layer, the step (C) of liquefying the surface of the first insulating layer, and the second photosensitive resin being applied to the first insulating layer. A step (D) of forming a second insulating material layer covering the first insulating layer by ejecting droplets of the second insulating material containing the mixture, and a step (E) of curing the second insulating material layer are performed. Includes.</p><p> According to the above configuration, since the surface of the first insulating layer is liquefied, a second insulating layer having a uniform thickness can be formed on the first insulating layer.</p><p> Preferably, the step (B) includes a step of irradiating the first insulating material layer with light of a first wavelength to cure the first insulating material layer. Then, the step (C) includes a step of irradiating the surface of the first insulating layer with light having a second wavelength different from the first wavelength to liquefy the surface of the first insulating layer. There is.</p><p> One of the effects obtained by the above configuration is that the curing of the first insulating material layer and the liquefaction of the first insulating layer can be achieved only by the step including light irradiation.</p><p> Furthermore, the present invention can be realized in various forms. For example, the present invention is realized in the form of a method for manufacturing a wiring board or a method for manufacturing an electronic device.</p>

(A. Overall configuration of the droplet ejection device) The manufacturing apparatus of the present embodiment has three droplet ejection devices. The three droplet ejection devices are devices that eject the insulating material 7A (Fig. 1), the conductive material 8A, and the insulating material 9A, respectively. As will be described later, these insulating material 7A, conductive material 8A, and insulating material 9A are all types of liquid materials.

The droplet ejection device 1 shown in FIG. 1 is basically an inkjet device. More specifically, the droplet ejection device 1 includes a tank 101 holding a liquid material 111, a tube 110, a ground stage GS, an ejection head portion 103, a stage 106, and a first position control device 104. The second position control device 108, the control unit 112, the light irradiation device 140, and the support unit 104a are provided. The structure and function of the other two droplet ejection devices 2 and 3 are basically the same as the structure and function of the droplet ejection device 1, and therefore, of these two droplet ejection devices 2 and 3. The description of the structure and function is omitted.

The discharge head portion 103 holds the head 114 (FIG. 2). The head 114 ejects droplets of the liquid material 111 in response to a signal from the control unit 112. The head 114 in the discharge head portion 103 is connected to the tank 101 by a tube 110, so that the liquid material 111 is supplied from the tank 101 to the head 114.

The stage 106 provides a flat surface for fixing the substrate 10A. Further, the stage 106 also has a function of fixing the position of the substrate 10A by using a suction force. Here, the substrate 10A is a flexible substrate made of polyimide, and its shape is tape-shaped. Both ends of the substrate 10A are fixed to a pair of reels (not shown).

The first position control device 104 is fixed at a predetermined height position from the ground stage GS by the support portion 104a. The first position control device 104 has a function of moving the discharge head unit 103 along the X-axis direction and the Z-axis direction orthogonal to the X-axis direction in response to a signal from the control unit 112. Further, the first position control device 104 also has a function of rotating the discharge head portion 103 around an axis parallel to the Z axis. Here, in the present embodiment, the Z-axis direction is a direction parallel to the vertical direction (that is, the direction of gravitational acceleration).

The second position control device 108 moves the stage 106 in the Y-axis direction on the ground stage GS in response to the signal from the control unit 112. Here, the Y-axis direction is a direction orthogonal to both the X-axis direction and the Z-axis direction.

The configuration of the first position control device 104 and the configuration of the second position control device 108 having the above functions can be realized by using a known XY robot using a linear motor or a servomotor. Therefore, a detailed description of their configurations will be omitted here. In this specification, the first position control device 104 and the second position control device 108 are also referred to as "robot" or "scanning unit".

As described above, the discharge head portion 103 is moved in the X-axis direction by the first position control device 104. Then, the substrate 10A moves in the Y-axis direction together with the stage 106 by the second position control device 108. As a result, the relative position of the head 114 with respect to the substrate 10A changes. More specifically, due to these operations, the discharge head portion 103, the head 114, or the nozzle 118 (FIG. 2) keeps a predetermined distance in the Z-axis direction with respect to the substrate 10A in the X-axis direction and Y. It moves relative to the axial direction, that is, scans relatively. "Relative movement" or "relative scanning" means that at least one of the side that ejects the liquid material 111 and the side that the ejected material from the liquid material 111 lands (the ejected portion) moves relative to the other. To do.

The control unit 112 is configured to receive discharge data indicating a relative position at which droplets of the liquid material 111 should be discharged from an external information processing device. The control unit 112 stores the received discharge data in an internal storage device, and controls the first position control device 104, the second position control device 108, and the head 114 according to the stored discharge data. To do. The discharge data is data for applying the liquid material 111 on the substrate 10A in a predetermined pattern. In this embodiment, the discharge data has a form of bitmap data.

The droplet ejection device 1 having the above configuration moves the nozzle 118 (FIG. 2) of the head 114 relative to the substrate 10A according to the ejection data, and the liquid material 111 from the nozzle 118 toward the ejection portion. Is discharged. The relative movement of the head 114 by the droplet ejection device 1 and the ejection of the liquid material 111 from the head 114 may be collectively referred to as "coating scanning" or "discharging scanning".

In the present specification, the portion where the droplet of the liquid material 111 lands is also referred to as the discharged portion. Then, the portion where the landed droplets get wet and spread is also referred to as a "coated portion". Both the "discharged portion" and the "coated portion" are also portions formed by subjecting the underlying object to a surface modification treatment so that the liquid material exhibits a desired contact angle. However, even if the surface modification treatment is not performed, the surface of the underlying object exhibits the desired liquid repellency or positivity with respect to the liquid material (that is, the landed liquid material is on the surface of the underlying object. In the case of (exposing a desired contact angle), the surface itself of the underlying object may be the "discharged portion" or the "applied portion". In addition, in this specification, a "discharge part" is also referred to as a "target" or a "reception part".

Now, returning to FIG. 1, the light irradiation device 140 is a device that irradiates the liquid material 111 attached to the substrate 10A with ultraviolet light. The control unit 112 also controls ON / OFF of the irradiation of ultraviolet light of the light irradiation device 140.

Forming a layer, a film, or a pattern by an inkjet method means forming a layer, a film, or a pattern on a predetermined object by using the droplet ejection device 1 as described above.

(B. Head) As shown in FIGS. 2A and 2B, the head 114 in the droplet ejection device 1 is an inkjet head having a plurality of nozzles 118. Specifically, the head 114 includes a diaphragm 126 and a nozzle plate 128 that defines the opening of the nozzle 118. A liquid pool 129 is located between the diaphragm 126 and the nozzle plate 128, and the liquid material 111 supplied to the liquid pool 129 from an external tank (not shown) through a hole 131. Is always filled.

Further, a plurality of partition walls 122 are located between the diaphragm 126 and the nozzle plate 128. The portion surrounded by the diaphragm 126, the nozzle plate 128, and the pair of partition walls 122 is the cavity 120. Since the cavities 120 are provided corresponding to the nozzles 118, the number of cavities 120 and the number of nozzles 118 are the same. The liquid material 111 is supplied to the cavity 120 from the liquid pool 129 via the supply port 130 located between the pair of partition walls 122. In this embodiment, the diameter of the nozzle 118 is about 27 μm.

By the way, on the diaphragm 126, each oscillator 124 is located corresponding to each cavity 120. Each of the oscillators 124 includes a piezo element 124C and a pair of electrodes 124A and 124B sandwiching the piezo element 124C. When the control unit 112 applies a driving voltage between the pair of electrodes 124A and 124B, the droplet D of the liquid material 111 is discharged from the corresponding nozzle 118. Here, the volume of the material discharged from the nozzle 118 is variable between 0 pl and 42 pl (picolitre) or less. The shape of the nozzle 118 is adjusted so that the droplet D of the liquid material 111 is ejected from the nozzle 118 in the Z-axis direction.

In the present specification, a portion including one nozzle 118, a cavity 120 corresponding to the nozzle 118, and an oscillator 124 corresponding to the cavity 120 may be referred to as a discharge unit 127. According to this notation, one head 114 has as many discharges 127 as there are nozzles 118. The discharge unit 127 may have an electric heat conversion element instead of the piezo element. That is, the discharge unit 127 may have a configuration in which the material is discharged by utilizing the thermal expansion of the material by the electric heat conversion element.

(C. Control unit) Next, the configuration of the control unit 112 will be described. As shown in FIG. 3, the control unit 112 includes an input buffer memory 200, a storage device 202, a processing unit 204, a light source driving unit 205, a scanning driving unit 206, and a head driving unit 208. .. The input buffer memory 200 and the processing unit 204 are connected to each other so as to be able to communicate with each other. The processing unit 204, the storage device 202, the light source driving unit 205, the scanning driving unit 206, and the head driving unit 208 are connected to each other by a bus (not shown) so as to be able to communicate with each other.

The light source driving unit 205 is communicatively connected to the light irradiation device 140. Further, the scanning drive unit 206 is communicably connected to the first position control device 104 and the second position control device 108. Similarly, the head drive unit 208 is connected to the head 114 so as to be able to communicate with each other.

The input buffer memory 200 receives discharge data for discharging droplets of the liquid material 111 from an external information processing device (not shown) located outside the droplet discharge device 1. The input buffer memory 200 supplies the discharge data to the processing unit 204, and the processing unit 204 stores the discharge data in the storage device 202. In FIG. 3, the storage device 202 is RAM.

The processing unit 204 gives the scanning drive unit 206 data indicating the relative position of the nozzle 118 with respect to the discharge unit based on the discharge data in the storage device 202. The scanning drive unit 206 gives the first position control device 104 and the second position control device 108 a stage drive signal according to this data, the discharge cycle, and the discharge cycle. As a result, the relative position of the discharge head portion 103 with respect to the discharge portion changes. On the other hand, the processing unit 204 gives the head 114 a discharge signal necessary for discharging the liquid material 111 based on the discharge data stored in the storage device 202. As a result, a droplet D of the liquid material 111 is ejected from the corresponding nozzle 118 in the head 114.

Further, the processing unit 204 sets the light irradiation device 140 into either an ON state or an OFF state based on the discharge data in the storage device 202. Specifically, the processing unit 204 supplies each signal indicating the ON state or the OFF state to the light source driving unit 205 so that the light source driving unit 205 can set the state of the light irradiation device 140.

The control unit 112 is a computer including a CPU, ROM, RAM, and a bus. Therefore, the above-mentioned function of the control unit 112 is realized by a software program executed by a computer. Of course, the control unit 112 may be realized by a dedicated circuit (hardware).

(D. Liquid material) The above-mentioned "liquid material 111" refers to a material having a viscosity that can be discharged as droplets D from the nozzle 118 of the head 114. Here, it does not matter whether the liquid material 111 is water-based or oil-based. It suffices to have fluidity (viscosity) that can be discharged from the nozzle 118, and even if a solid substance is mixed, it may be a fluid as a whole. Here, the viscosity of the liquid material 111 is preferably 1 mPa · s or more and 50 mPa · s or less. When the viscosity is 1 mPa · s or more, the peripheral portion of the nozzle 118 is less likely to be contaminated with the liquid material 111 when the droplet D of the liquid material 111 is discharged. On the other hand, when the viscosity is 50 mPa · s or less, the clogging frequency of the nozzle 118 is low, and therefore smooth ejection of the droplet D can be realized.

The conductive material 8A (FIG. 4 (d)) described later is a kind of the liquid material 111 described above. The conductive material 8A of the present embodiment contains silver particles having an average particle size of about 10 nm and a dispersion medium. Then, in the conductive material 8A, the silver particles are stably dispersed in the dispersion medium. The silver particles may be coated with a coating agent. Here, the coating agent is a compound capable of coordinating with a silver atom.

As such a coating agent, amines, alcohols, thiols and the like are known. More specifically, as a coating agent, amine compounds such as 2-methylaminoethanol, diethanolamine, diethylmethylamine, 2-dimethylaminoethanol and methyldiethanolamine, alkylamines, ethylenediamine, alkylalcohols, ethylene glycol and propylene glycol , Alkylthiols and ethanedithiol can be used.

The dispersion medium (or solvent) is not particularly limited as long as it can disperse conductive fine particles such as silver nanoparticles and does not cause aggregation. For example, in addition to water, alcohols such as methanol, ethanol, compounds and butanol, n-heptane, n-octane, decane, dodecane, tetradecane, toluene, xylene, simen, durene, inden, dipentene, tetrahydronaphthalene, decahydro. Hydrocarbon compounds such as naphthalene and cyclohexylbenzene, as well as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol methyl ethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, 1,2-dimethoxyethane, and bis (2-). Examples thereof include ether compounds such as methoxyethyl) ether and p-dioxane, and polar compounds such as propylene carbonate, γ-butyrolactone, N-methyl-2-pyrrolidone, dimethylformamide, dimethylsulfoxide and cyclohexanone. Of these, water, alcohols, hydrocarbon compounds, and ether compounds are preferable and more preferable in terms of the dispersibility of the conductive fine particles, the stability of the dispersion liquid, and the ease of application to the droplet ejection method. Examples of the dispersion medium include water and hydrocarbon compounds.

Particles with an average particle size of about 1 nm to several hundred nm are also referred to as "nanoparticles". According to this notation, the conductive material 8A contains silver nanoparticles.

Further, the insulating material 7A (FIG. 4) and the insulating material 9A (FIG. 6), which will be described later, are also liquid materials 111. The insulating material 7A and the insulating material 9A contain a photosensitive resin. The photosensitive resin of the present embodiment contains a photopolymerization initiator, an acrylic acid monomer and / or an oligomer. The acrylic photosensitive resin of the present embodiment corresponds to the "first photosensitive resin" and the "second photosensitive resin" of the present invention. As described above, in the present embodiment, the "first photosensitive resin" and the "second photosensitive resin" are the same as each other.

Hereinafter, a method for manufacturing a wiring board using the method for forming a multilayer structure of the present embodiment will be described.

(E. Manufacturing method) First, one surface S of the substrate 10A is UV-cleaned. UV cleaning not only cleans the surface S, but also makes the surface S exhibit appropriate liquidity with respect to the liquid insulating material 7A described later. Therefore, in the present embodiment, the surface S after UV cleaning becomes the above-mentioned discharged portion and coated portion. Further, in the present embodiment, the surface S is an example of the "object surface" of the present invention.

Next, as shown in FIG. 4A, the insulating material layer 7B is formed on the entire surface S using the droplet ejection device 1. Specifically, first, the substrate 10A is positioned on the stage 106 of the droplet ejection device 1. Then, the droplet ejection device 1 changes the relative position of the nozzle 118 with respect to the surface S in two dimensions (that is, in the X-axis direction and the Y-axis direction). Then, the droplet ejection device 1 ejects the droplet D of the liquid insulating material 7A toward the surface S from the nozzle 118 at a predetermined cycle according to the first ejection data. Then, a plurality of droplets D land at a predetermined pitch over the entire surface S and spread wet. Then, when the plurality of landed droplets D get wet and spread, the insulating material layer 7B covering the surface S is obtained. The volume and number of droplets D of the insulating material 7A to be discharged are set so that the thickness of the insulating layer 7 (FIG. 4 (c)) obtained after the curing step described later is about 10 μm. There is.

Here, the nozzle 118 in the head 114 of the droplet ejection device 1 is also referred to as a first nozzle.

In the present embodiment, the substrate 10A and one or more layers provided on the substrate 10A are collectively referred to as "base 10B".

After forming the insulating material layer 7B, the obtained insulating material layer 7B is cured to form the insulating layer 7 as shown in FIGS. 4 (b) and 4 (c). Specifically, the insulating material layer 7B is irradiated with light having a first wavelength belonging to the ultraviolet region from the light irradiating device 140 for about 60 seconds to obtain the insulating layer 7. In this embodiment, the wavelength of the light irradiating the insulating material layer 7B is 365 nm.

In this way, before the pattern of the conductive material layer 8B (FIG. 4 (d)) described later is formed, the insulating material layer 7B which is the base thereof is cured, so that the pattern of the conductive material layer 8B is broken. Absent.

Next, as shown in FIG. 4D, the pattern of the conductive material layer 8B is formed on the insulating layer 7 by using the droplet ejection device 2. Specifically, first, the substrate 10A is positioned on the stage 106 of the droplet ejection device 2. Then, the droplet ejection device 2 changes the relative position of the nozzle 118 with respect to the surface of the insulating layer 7 two-dimensionally. Then, the droplet ejection device 2 receives the liquid conductive material 8A toward the surface of the insulating layer 7 each time the nozzle 118 reaches the position corresponding to the pattern of the conductive material layer 8B according to the second ejection data. Droplet D is discharged from the nozzle 118. Then, a plurality of droplets D land on the insulating layer 7 and spread wet. Then, when the plurality of landed droplets D get wet and spread, the pattern of the conductive material layer 8B is formed on the insulating layer 7. The volume and number of droplets D of the conductive material 8A to be discharged are set so that the thickness of the conductive layer 8 (FIG. 5 (b)) obtained after the heating step described later is about 4 μm. ing.

Here, the nozzle 118 in the head 114 of the droplet ejection device 2 is also referred to as a second nozzle.

In this embodiment, as shown in FIG. 5A, the pattern of the conductive material layer 8B includes two stripes parallel to each other. Each of the two stripes is located on a portion of the insulating layer 7. The width of each of the two striped portions is about 50 μm, and the longitudinal method thereof extends in the direction perpendicular to the paper surface of FIG. 5 (a).

Next, the pattern of the conductive material layer 8B is activated as shown in FIG. 5 (a) to form the pattern of the conductive layer 8 shown in FIG. 5 (b). Specifically, the pattern of the conductive material layer 8B is fired (heated) at a temperature of 150 ° C. for 30 minutes using a clean heater. Then, the silver particles in the conductive material layer 8B are fired or fused to obtain the pattern of the conductive layer 8. Here, the pattern of the conductive layer 8 corresponds to the "wiring pattern" of the present invention. In this specification, the pattern of the conductive layer 8 is also referred to as a conductive pattern.

As described above, in the present embodiment, the conductive material layer 8B is fired in advance to form the conductive layer 8 before the insulating material layer 9B (described later) covering the insulating layer 7 and the wiring pattern is provided. Then, the obtained conductive layer 8 is stressed by the curing of the insulating material layer 9B.<u style="single">To</u>Therefore, it is less likely to be deformed. This is because the adhesive force between the insulating layer 7 and the conductive layer 8 is stronger than the adhesive force between the insulating layer 7 and the conductive material layer 8B (the conductive layer 8 before being activated).

After forming the wiring pattern (the pattern of the conductive layer 8), the surface of the insulating layer 7 and the surface of the wiring pattern are liquefied as shown in FIG. 5 (c). Specifically, the surface of the insulating layer 7 and the surface of the conductive layer 8 are uniformly irradiated with light having a second wavelength different from the first wavelength described above for about 60 seconds. In this embodiment, the second wavelength is 172 nm. Then, the surface of the insulating layer 7 and the surface of the wiring pattern become liquid-friendly with respect to the liquid insulating material 9A (FIG. 6 (a)) described later. Here, one of the indexes showing the degree of positivity is the "contact angle". In the present embodiment, when the droplet D of the insulating material 9A comes into contact with the surface of the liquefied insulating layer 7 or the surface of the wiring pattern, the contact angle between the surface and the droplet D is 20 degrees or less. is there.

The reason for liquefying the surface of the insulating layer 7 and the surface of the wiring pattern is as follows. After undergoing a curing step for obtaining the insulating layer 7 or a firing (heating) step for obtaining a wiring pattern, these surfaces become liquid-repellent with respect to the liquid insulating material 9A. Here, when the surface of the object exhibits liquid repellency, it becomes difficult to form a uniform layer over a wide area. On the other hand, in the present embodiment, since the surface of the insulating layer 7 and the surface of the wiring pattern are liquefied after the firing step, the degree to which the droplets of the insulating material 9A are wetted and spread (the degree of positivity) is. , It grows again over the surface of the insulating layer 7 and the surface of the wiring pattern 25. Therefore, an insulating layer 9 having a flat surface can be formed over these surfaces. Moreover, the thickness of the insulating layer 9 becomes uniform on each of the insulating layer 7 and the wiring pattern.

After the above-mentioned liquefaction, as shown in FIG. 6A, the insulating material layer 9B covering the insulating layer 7 and the pattern of the conductive layer 8 is formed by using the droplet ejection device 3. .. Specifically, the substrate 10A is positioned on the stage 106 of the droplet ejection device 3. Then, the droplet ejection device 3 two-dimensionally changes the relative position of the nozzle 118 with respect to the pattern of the insulating layer 7 and the conductive layer 8. Then, the droplet ejection device 3 ejects the droplet D of the liquid insulating material 9A from the nozzle 118 at a predetermined cycle toward the insulating layer 7 and the pattern of the conductive layer 8 according to the third ejection data. To do. Then, a plurality of droplets D land at a predetermined pitch over the entire area of the insulating layer 7 and the pattern of the conductive layer 8 and spread wet. Then, when the plurality of landed droplets D get wet and spread, an insulating material layer 9B covering the insulating layer 7 and the pattern of the conductive layer 8 is obtained. The volume and number of droplets D of the insulating material 9A to be discharged are set so that the thickness of the insulating layer 9 (FIG. 6 (d)) obtained after the heating step described later is about 10 μm. There is.

Here, the nozzle 118 in the head 114 of the droplet ejection device 3 is also referred to as a third nozzle.

After forming the insulating material layer 9B, as shown in FIG. 6B, the obtained insulating material layer 9B is semi-cured to form the insulating material layer 9B'. Specifically, the insulating material layer 9B is irradiated with light having a wavelength in the ultraviolet region from the light irradiation device 140 for about 4 seconds to obtain the insulating material layer 9B'in a semi-cured state. In the present embodiment, the wavelength of the light irradiating the insulating material layer 9B is 365 nm.

Here, when the insulating material layer or the insulating material is semi-cured, the state of the photosensitive resin constituting the insulating material layer is between the state at the time of ejection and the substantially cured state by light irradiation. Means that. In the present embodiment, such an intermediate state is the above-mentioned "semi-cured state". The state at the time of ejection is a state in which the photosensitive resin (insulating material 7A) has a viscosity that allows it to be ejected from the nozzle 118.

Instead of semi-curing the insulating material layer 9B, the insulating material layer 9B may be substantially cured by lengthening the time for irradiating the insulating material layer 9B with light (for example, 60 seconds).

After obtaining the semi-cured insulating material layer 9B', the substrate 10B is heated to give a calorific value Q as shown in FIG. 6 (c). In this embodiment, the substrate 10B is heated at a temperature of 150 degrees for about 60 minutes using a clean oven. By this heating, the polymerization reaction of the photosensitive resin in the insulating material layer 9B'progresses further, and the insulating material layer 9B' is cured. As a result, the insulating material layer 9B'becomes the insulating layer 9. Even when the insulating material layer 9B is cured by light irradiation, it is preferable to perform such a heating step.

Here, even when a monomer or an oligomer whose polymerization reaction is incomplete is present in the previously formed insulating layer 7, the insulating layer 7 is subjected to a heating step for curing the insulating material layer 9B'. The polymerization reaction in is surely completed. Similarly, this heating step completely promotes the sintering or fusion of the silver nanoparticles in the conductive layer 8 so that the electrical conduction in the conductive layer 8 is more reliable.

Through the above steps, as shown in FIG. 6D, the insulating layer 7 covering the substrate 10A, the pattern of the conductive layer 8 located on the insulating layer 7, and the pattern of the insulating layer 7 and the conductive layer 8 are covered. A multilayer structure composed of the insulating layer 9 and the insulating layer 9 can be obtained. In the present embodiment, the insulating layer 7 and the insulating layer 9 are made of acrylic resin, and the conductive layer 8 is made of silver wiring. The substrate 10A provided with the conductive layer 8 is also referred to as wiring substrate 10.

(F. Mounting process) Next, as shown in FIG. 7, the liquid crystal panel 32 and the semiconductor element 25 are mounted on the wiring board 10. Specifically, a portion where the pattern of the conductive layer 8 is not covered by the insulating layer 9 is formed on a part of the wiring board 10. Then, the pad of the liquid crystal panel or the corresponding pad of the semiconductor element 25 is joined to the exposed pattern of the conductive layer 8. In this way, the liquid crystal display device 34 is obtained. As described above, the manufacturing method of the present embodiment can be applied to the manufacturing of the liquid crystal display device 34. In this embodiment, the semiconductor element 25 is a liquid crystal driver circuit.

Further, the manufacturing method of the present embodiment is applied not only to the manufacturing of a liquid crystal display device but also to the manufacturing of various electro-optical devices. The "electro-optical device" here is not limited to a device that utilizes changes in optical characteristics (so-called electro-optical effect) such as changes in birefringence, optical rotation, and light scattering. , Means all devices that emit, transmit, or reflect light in response to the application of a signal voltage.

Specifically, the electro-optical device includes a liquid crystal display device, an electroluminescence display device, a plasma display device, a display using a surface-conduction electron emitting element (SED: Surface-Conduction Electron-Emitter Display), and a field emission display (SED). FED: Field Emission Display) and other terms.

Further, the method for forming a multilayer structure of the present embodiment can be applied to various methods for manufacturing electronic devices. For example, the present embodiment also includes a method of manufacturing a mobile phone 500 having an electro-optical device 520 as shown in FIG. 8 and a method of manufacturing a personal computer 600 having an electro-optic device 620 as shown in FIG. The manufacturing method of is applied.

(Modification 1) According to the above embodiment, the three different droplet ejection devices 1, 2, and 3 eject the insulating material 7A, the conductive material 8A, and the insulating material 9A, respectively. Instead of such a configuration, one droplet ejection device (for example, the droplet ejection device 1) may eject all of the above-mentioned insulating material 7A, conductive material 8A, and insulating material 9A. In this case, the insulating material 7A, the conductive material 8A, and the insulating material 9A may be discharged from separate nozzles 118 in the droplet ejection device 1, or may be ejected from one nozzle 118 in the droplet ejection device 1. May be good. When these three liquid materials are discharged from one nozzle 118, a step of cleaning the path from the tank 101 to the nozzle 118 may be added when switching the liquid materials.

Here, when these three liquid materials are discharged from one nozzle, the above-mentioned "first nozzle", "second nozzle", and "third nozzle" are one and the same nozzle 118. Corresponds to.

(Modification 2) In the above embodiment, a multilayer structure is provided on the substrate 10A made of polyimide. However, even if a ceramic substrate, a glass substrate, an epoxy substrate, a glass epoxy substrate, a silicon substrate, or the like is used instead of such a substrate 10A, the same effect as that described in the above embodiment can be obtained.

(Modification 3) The conductive material 8A of the above embodiment contains silver nanoparticles. However, instead of silver nanoparticles, nanoparticles of other metals may be used. Here, as another metal, for example, any one of gold, platinum, copper, palladium, rhodium, osmium, ruthenium, iridium, iron, tin, zinc, cobalt, nickel, chromium, titanium, tantalum, tungsten, and indium is used. It may be utilized, or an alloy in which any two or more of them are combined may be utilized. However, since silver can be reduced at a relatively low temperature, it is easy to handle. In this respect, when using a droplet ejection device, it is not possible to use the conductive material 8A containing silver nanoparticles. preferable.

Further, the conductive material 8A may contain an organometallic compound instead of the metal nanoparticles. The organometallic compound referred to here is a compound in which a metal is precipitated by decomposition by heating. Such organometallic compounds include chlorotriethylphosphine gold (I), chlorotrimethylphosphine gold (I), chlorotriphenylphosphine gold (I), silver (I) 2,4-pentandionato complex, trimethylphosphine (hexa). Fluoroacetylacetonate) silver (I) complex, copper (I) hexafluoropentanetocyclooctadiene complex, etc.

As described above, the form of the metal contained in the liquid conductive material 8A may be the form of particles typified by nanoparticles or the form of a compound such as an organometallic compound.

Further, the conductive material 8A may contain a polymer-based soluble material such as polyaniline, polythiophene, or polyphenylene vinylene instead of the metal.

(Modification 4) In the above embodiment, the insulating layer 7 and the insulating layer 9 are made of the same material. However, the insulating layer 7 and the insulating layer 9 may be made of different materials. For example, the insulating layer 7 may be an acrylic resin and the insulating layer 9 may be a polyimide resin. In this case, the insulating material 7A may be a liquid material containing a monomer or oligomer of a photosensitive acrylic resin, and the insulating material 9A may be a liquid material containing a photosensitive polyimide precursor. That is, in this case, the "first photosensitive resin" and the "second photosensitive resin" of the present invention are different from each other.

(Modification 5) According to the above embodiment, the pattern of the conductive layer 8 is formed on the insulating layer 7. However, the method for forming a multilayer structure according to the above embodiment is not limited to the formation of such a structure. Specifically, the pattern of the conductive layer 8 on the insulating layer 7 may be omitted. Then, the insulating material layer is formed by using the droplet ejection device so that the total thickness of the plurality of laminated insulating layers becomes a desired value, and the formed insulating material layer is cured to insulate. The process of obtaining the layer, liquefying the surface of the insulating layer, and forming the insulating material layer again on the liquefied insulating layer using a droplet ejection device may be repeated.

Rather than obtaining an insulating layer of a desired thickness from the insulating material layer formed by discharge by a single curing step, the insulation of a desired thickness is insulated by repeating the formation of the insulating material layer, liquefaction, and the curing step. It is easier to form a layer so that the total drying time is shorter and the final insulating layer has a uniform thickness.

(Modification 6) According to the above embodiment, the surface of the insulating layer 7 and the surface of the wiring pattern are liquefied by irradiating light having a wavelength in the ultraviolet region. However, instead of such liquefaction, oxygen is used as the processing gas in the atmosphere.₂Even if plasma treatment is performed, the surface of the insulating layer 7 and the surface of the wiring pattern can be liquefied. O₂The plasma treatment is a treatment of irradiating the substrate 10A (base 10B) with oxygen in a plasma state from a plasma discharge electrode (not shown). O₂The conditions for plasma treatment are that the plasma power is 50 to 1000 W, the oxygen gas flow rate is 50 to 100 mL / min, the relative movement speed of the substrate 10 with respect to the plasma discharge electrode is 0.5 to 10 mm / sec, and the substrate temperature is 70 to 90 ° C. Just do it.

<figref num="1">The schematic diagram which shows the droplet ejection device of this embodiment.</figref><figref num="2">(a) and (b) are schematic views showing a head in a droplet ejection device.</figref><figref num="3">The functional block diagram of the control part in the droplet ejection device.</figref><figref num="4">(a) to (d) are diagrams for explaining the manufacturing method of the wiring board of the present embodiment.</figref><figref num="5">(a) to (c) are diagrams for explaining the manufacturing method of the wiring board of the present embodiment.</figref><figref num="6">(a) to (d) are diagrams for explaining the manufacturing method of the wiring board of the present embodiment.</figref><figref num="7">The schematic diagram of the liquid crystal display device of this embodiment.</figref><figref num="8">The schematic diagram which shows the mobile phone of this embodiment.</figref><figref num="9">The schematic diagram which shows the personal computer of this embodiment.</figref>

Code description

7 ... Insulation layer 7A ... 1st insulation material, 7B ... 1st insulation material layer, 8 ... Conductive layer, 8A ... Conductive material, 8B ... Conductive material layer, 9 ... 1st Insulation Layer, 9A ... 2nd Insulation Material, 9B ... 2nd Insulation Material Layer, 10 ... Wiring Board, 10A ... Board, 10B ... Base, 25 ... Semiconductor element, 32 ... liquid crystal panel, 34 ... liquid crystal display device, 1, 2, 3 ... droplet ejection device, 104 ... 1st position control device, 106 ... stage, 108 .. Second position control device, 112 ... control unit, 114 ... head, 118 ... nozzle, 140 ... light irradiation device, 500 ... mobile phone, 520 ... electro-optical device, 600 ... personal computer, 620 ... electro-optical device.