Electronic apparatus, and method of manufacturing the same

The present invention relates to an electronic device in which an electronic component bonded on a substrate is sealed with a cap body, and a method for manufacturing the same.

Conventionally, an electronic device for surface mounting in which an electronic component bonded to a substrate is sealed with a cap body has been widely used. For example, as a clock source for electronic circuits of various electronic devices such as information communication equipment, OA equipment such as computers, and consumer equipment, a piezoelectric vibrating piece as an electronic component is bonded to a substrate, and the substrate is covered so as to cover the piezoelectric vibrating piece. A piezoelectric device is widely used as an electronic device in which a piezoelectric vibrating piece is airtightly sealed in a concave space formed by a substrate and a cap body by joining a concave cap body on the top (see, for example, Patent Document 1). ).

The piezoelectric device (crystal oscillator) described in Patent Document 1 includes a flat plate-shaped substrate (flat plate-shaped substrate), a piezoelectric vibrating piece (crystal piece), and a concave cap body (metal cover) having a flange. doing. The ceramic substrate is provided with an external mounting terminal on one main surface, which is the outer bottom surface of the piezoelectric device, and a metal layer (metal film) is provided on the peripheral edge of the other main surface, and the metal layer is provided. It has a junction terminal (crystal terminal) to which the piezoelectric vibrating piece is bonded inside. Then, after joining one end of the piezoelectric vibrating piece to the joining terminal of the substrate with a joining member such as a conductive adhesive, the opening end surface of the cap body and the outer peripheral end of the substrate are positioned inward, and the outer peripheral surface of the cap body and the substrate are positioned. The piezoelectric vibrating piece is hermetically sealed in the recessed space formed by the substrate and the cap body by bringing the brazing material into contact with the vicinity of the contact portion with the metal layer of the above material, heating and melting the brazing material, and brazing the brazing material. ing.

<p><patcit num="1"><text>Japanese Unexamined Patent Publication No. 2003-318690</text></patcit></p>

<p> However, in the piezoelectric device described in Patent Document 1, the cap body is displaced on the substrate to which the piezoelectric vibrating pieces are joined, and for example, the cap body protrudes from the outer periphery of the piezoelectric device to satisfy the dimensional standard of the planar outer shape. There is a risk that the appearance will be poor without this, and there is a risk that the joint strength and air density of the cap body will decrease. Further, since the contact portion provided for joining the cap body and the substrate is limited to the open end surface of the cap body, the bonding strength between the cap body and the substrate is lowered, and the impact resistance and the bonding strength are deteriorated, or due to them. There is a problem that the air density of the sealing may decrease.</p>

<p> The present invention has been made to solve at least a part of the above-mentioned problems, and can be realized as the following forms or application examples.</p><p> [Application Example 1] The electronic device according to this application example is<u style="single">An electronic component joining region, a step portion around the electronic component joining region, and a surface between the electronic component joining region and the step portion and inclined from the step portion side to the electronic component joining region side. It has a substrate with a wall surface, an electronic component joined to the electronic component joining region, a recess, and a flange-shaped contact leg portion provided on the outer peripheral portion of the recess and facing the step portion. A cap body that covers the electronic component and is joined to the step portion is provided, and a boundary portion between the inner peripheral surface of the recess and the surface of the contact leg portion on the step portion side is a boundary portion of the substrate. Being located in the wall surface in plan view</u>It is characterized by.</p><p> According to the electronic device of the above application example, when the cap body is joined to the substrate so as to cover the electronic component joined to the electronic component joining region, even if there is a manufacturing variation in the opening shape of the cap body, the electronic component The cap body can be easily positioned by using the wall surface inclined from the joint region side to the step side as a guide. Further, since the bonding surface of the cap body is formed on the step portion and the wall surface of the substrate, the substrate of the cap body is suppressed while suppressing the increase in the area of the substrate as compared with the case where the cap is bonded to the flat surface of the substrate. The bonding strength can be improved by increasing the bonding area to. Therefore, the electronic components can be reliably airtightly sealed by firmly joining the cap body to the substrate while preventing the position of the cap body from being displaced. Therefore, small electrons having excellent impact resistance against dropping and having high reliability. Equipment can be provided.</p><p>[Application Example 2] In the electronic device according to the above application example,<u style="single">The cross-sectional shape of the connecting portion between the wall surface and the step portion is curved.</u>It is characterized by.</p><p> According to this configuration, it is possible to suppress the occurrence of cracks and the like that may occur when stress is generated at the connecting portion between the step portion and the wall surface, which is the base point at which the thickness of the substrate is reduced.</p><p> [Application Example 3] In the electronic device according to the above application example<u style="single">A metal layer is formed on the step portion and the wall surface, the metal layer on the wall surface and the boundary portion are in contact with each other, and outside the contact portion between the metal layer and the boundary portion, the step portion is formed. The upper metal layer and the contact leg portion are joined via a brazing material, and inside the contact portion, the metal layer on the wall surface and the inner peripheral surface of the recess are via a brazing material. It is characterized by being joined.</u></p><p> According to this configuration, in the bonding between the cap body and the substrate, a stronger and better bonding can be performed by using a bonding member made of a metal, an alloy, or the like. For example, by brazing an alloy (brazing) having a melting point lower than that of the metal of the joint portion of the cap body and the wall surface as a joining member, the metal or metal layer on the cap body or the substrate side is not melted. Can be firmly joined.</p><p> [Application Example 4] In the electronic device according to the above application example<u style="single">The metal layer on the wall surface is provided with a gap from the electronic component joining region.</u>It is characterized by that.</p><p> According to this configuration, for example, when the substrate and the cap body are joined via a joining member made of metal or alloy, the molten droplets of the joining metal generated at the time of joining are suppressed from being scattered on the electronic component. Can be done.</p><p> [Application Example 5] The method for manufacturing an electronic device according to this application example is as follows.<u style="single">An electronic component joining region, a stepped portion around the electronic component joining region, and a surface between the electronic component joining region and the stepped portion and inclined from the stepped portion side to the electronic component joining region side. It has a substrate with a wall surface, an electronic component joined to the electronic component joining region, a recess, and a flange-shaped contact leg portion provided on the outer peripheral portion of the recess and facing the step portion. A cap body that covers the electronic component and is joined to the step portion is provided, and a boundary portion between the inner peripheral surface of the recess and the surface of the contact leg portion on the step portion side is a boundary portion of the substrate. In a plan view, it is a method of manufacturing an electronic device located in the wall surface, in which a step of preparing a substrate sheet on which the substrate can be formed and a pressing process divide the substrate sheet into individual pieces of the substrate. The step includes a step of forming a split groove for forming the split groove, a step of joining the electronic component to the electronic component joining region, and a step of joining the cap body to the substrate so as to cover the electronic component.</u>It is characterized by that.</p><p> According to the manufacturing method of the electronic device of the above application example, even if there is a manufacturing variation in the opening shape of the cap body in the step of joining the cap body, the wall surface inclined from the electronic component joining region side to the step portion side is guided. It is possible to manufacture an electronic device capable of easily positioning the cap body. Further, since the joint surface between the step portion and the wall surface of the substrate is formed with the cap body, the cap body can be used while suppressing an increase in the area of the substrate as compared with an electronic device for joining the cap to the flat surface of the substrate. The bonding strength can be improved by increasing the bonding area to the substrate. Therefore, in the split groove forming step included in the manufacturing process of the conventional electronic device, only by adding the step of forming the step portion by using the pressing blade for forming the step portion, the impact resistance against dropping and the like is excellent and high. A reliable electronic device can be manufactured.</p><p> [Application Example 6] In the method for manufacturing an electronic device according to the above application example, an unfired ceramic sheet is used as the material of the substrate sheet, including a firing step of firing the ceramic sheet, and before the firing step.<u style="single">Including the split groove forming step</u>It is characterized by that.</p><p> According to this configuration, since the unfired ceramic sheet has plasticity, it is possible to easily form a stepped portion having a wall surface inclined from the electronic component joining region side toward the peripheral edge by pressing with a pressing blade. Can be done.</p><p> [Application Example 7] In the method for manufacturing an electronic device according to the above application example,<u style="single">The step portion has a rectangular shape with rounded corners in a plan view, and the division groove forming step includes a step of forming the rectangular step portion in a plan view and the corner portion of the step portion. Steps to process into a curved shape,</u>It is characterized by including.</p><p> According to this configuration, by performing the pressing process in a plurality of times, the pressure applied at the time of one pressing process can be reduced, so that the damage applied to the substrate sheet is reduced and the forming position is formed at each corner portion. Can be finely adjusted and the shape can be stabilized.</p><p> [Application Example 8] In the method for manufacturing an electronic device according to the above application example,<u style="single">The cap body has a metal or a metal layer at least at a contact portion with the substrate, includes a conductor pattern forming step of forming a conductor pattern on the substrate sheet, and in the conductor pattern forming step, the wall surface of the substrate. The conductor pattern is formed in the vicinity of a portion to be formed and a connecting portion with at least one of the stepped portion and the wall surface of the stepped portion.</u>It is characterized by that.</p><p> According to this configuration, the cap body and the substrate can be firmly joined relatively easily via a joining member capable of joining metals to each other.</p>

<figref num="1">(a) is a schematic plan view of an embodiment of a piezoelectric device as an electronic device as viewed from above, and (b) is a schematic cross-sectional view showing the AA line cross section of (a).</figref><figref num="2">Partial sectional view which expands and explains part D of FIG. 1 (b) in detail.</figref><figref num="3">The flowchart explaining one Embodiment of the manufacturing method of a piezoelectric device.</figref><figref num="4">The schematic plan view which shows the process of manufacturing a ceramic substrate as a substrate by a green sheet.</figref><figref num="5">The schematic plan view which shows the process of manufacturing a ceramic substrate as a substrate by a green sheet.</figref><figref num="6">A partially enlarged cross-sectional view showing a process of manufacturing a ceramic substrate from a green sheet.</figref><figref num="7">A partially enlarged cross-sectional view showing a process of manufacturing a ceramic substrate from a green sheet.</figref><figref num="8">The schematic plan view which shows the process of manufacturing a ceramic substrate by a green sheet.</figref><figref num="9">A partially enlarged cross-sectional view showing a process of manufacturing a ceramic substrate from a green sheet.</figref><figref num="10">The flowchart explaining the modification of the manufacturing method of a piezoelectric device.</figref><figref num="11">The schematic plan view which shows the modification of the process of manufacturing a ceramic substrate by a green sheet.</figref><figref num="12">The schematic plan view which shows the modification of the process of manufacturing a ceramic substrate by a green sheet.</figref><figref num="13">FIG. 5 is a partial cross-sectional view illustrating a modification 2 of the piezoelectric device.</figref><figref num="14">FIG. 5 is a partial cross-sectional view illustrating a modification 3 of the piezoelectric device.</figref>

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

(Piezoelectric device) FIG. 1 illustrates an embodiment of a piezoelectric device as an electronic device. FIG. 1A is a schematic plan view seen from above, and FIG. 1B is a schematic cross-sectional view showing an AA line cross section of FIG. 1A. .. In FIG. 1A, a part of the cap body (19) provided above the piezoelectric device is cut out for convenience of explaining the internal structure of the piezoelectric device. Further, FIG. 2 is a partial cross-sectional view in which the D portion of FIG. 1 (b) is enlarged and described in detail.

In FIG. 1, the piezoelectric device 1 is joined on a ceramic substrate 10 as a substrate, a piezoelectric vibrating piece 20 as an electronic component bonded on the ceramic substrate 10, and a piezoelectric vibrating piece 20 so as to cover the piezoelectric vibrating piece 20. The piezoelectric vibrating piece 20 is hermetically sealed in the cavity T formed by the ceramic substrate 10 and the cap body 19 and having the concave cap body 19 formed therein.

The ceramic substrate 10 has a plurality of external mounting terminals 16 on one main surface of a flat plate-shaped insulating base material, and has a vibrating piece bonding terminal 18 to which a piezoelectric vibrating piece 20 is bonded on the other main surface. There is. The vibrating piece junction terminal 18 and other terminals (not shown) are provided by an in-layer wiring (via) 17 formed by embedding a conductor paste containing a refractory metal in a through hole (via hole) provided in the ceramic substrate 10. It is connected to the corresponding external mounting terminal 16. One main surface of the ceramic substrate 10 provided with the external mounting terminal 16 is the outer bottom surface of the piezoelectric device 1, and the external mounting terminal 16 provided on the outer bottom surface makes the piezoelectric device 1 an external mounting board such as an electronic device. Can be implemented. The ceramic substrate 10 of the present embodiment is formed by molding and processing a green sheet for a ceramic substrate and then firing it (details will be described later).

On the peripheral edge of the surface (the other main surface) on the vibrating piece bonding region side (the other main surface) as the electronic component bonding region provided with the vibrating piece bonding terminal 18 of the ceramic substrate 10, parallel to the surface of the vibrating piece bonding region and An annular step portion 11 is formed so as to surround the vibrating piece joint region. The wall surface 12 of the step formed by the step portion 11 and the vibrating piece joining region is provided so as to be inclined from the step portion 11 side to the surface side of the vibrating piece joining region. Further, an annular metal layer 13 is provided on the step portion 11 and the wall surface 12 so as to surround the vibrating piece joint region.

The piezoelectric vibrating piece 20 is provided with excitation electrodes 25 as counter electrodes on both main surfaces of a flat plate-shaped piezoelectric substrate formed of, for example, a piezoelectric material such as quartz. Further, external connection electrodes 26 are provided on one end side of each main surface of the piezoelectric vibration piece 20, and are electrically connected by wiring between electrodes drawn from the corresponding excitation electrodes 25. As the material of the piezoelectric vibrating piece 20, examples of the piezoelectric material other than quartz include lithium tantalate and lithium niobate, and examples of the material other than the piezoelectric material include silicon.

On the ceramic substrate 10 (on the other main surface side), the piezoelectric vibrating piece 20 has an external connection electrode 26 provided on one end side thereof aligned with the corresponding vibrating piece junction terminal 18 of the ceramic substrate 10, for example. It is joined by a joining member 39 such as silver paste while making an electrical connection, and is cantilevered with the other end side as a free end.

The concave cap body 19 is formed by molding a plate material made of a metal such as 42 alloy, Kovar, or phosphor bronze by a conventionally known sheet metal processing, a concave portion is formed in the central portion, and a step portion 11 is formed on the outer peripheral portion. A flange-shaped contact leg 19c that can face each other is formed in an annular shape over the entire circumference. That is, the cap body 19 has a horizontal portion 19a in the central portion, and is once bent in the vertical direction on the outer peripheral side of the horizontal portion 19a to form a side wall portion 19b, and further perpendicular to the outer peripheral side from the side wall portion 19b. By bending, an annular contact leg portion 19c substantially parallel to the horizontal portion 19a is formed on the outer peripheral portion of the cap body 19.

In the cap body 19, the contact leg portion 19c faces the step portion 11 of the ceramic substrate 10 with the opening side of the recess formed by the horizontal portion 19a and the side wall portion 19b facing the ceramic substrate 10 side. Is joined. In the present embodiment, as shown in FIG. 2, the metal layer 13 on the step portion 11 and the wall surface 12 of the ceramic substrate 10, the lower surface side of the contact leg portion 19c of the cap body 19, and the inside (recessed side) of the side surface thereof. The contact leg portion 19c of the above is joined via, for example, a brazing material 29 as a joining member made of an alloy having a relatively low melting point. The cap body 19 is for airtightly sealing the mounting area of the piezoelectric vibrating piece 20 by accommodating the piezoelectric vibrating piece 20 in the cavity T surrounded by the recess and the joint surface of the piezoelectric vibrating piece 20 of the ceramic substrate 10. belongs to.

Here, in the piezoelectric device 1 of the present embodiment, as described above, the wall surface 12 provided on the peripheral edge of the surface of the ceramic substrate 10 on the vibrating piece bonding region side is inclined toward the surface side of the vibrating piece bonding region. A connected step portion 11 is formed. As a result, the cap body 19 can be easily positioned by fitting the cap body 19 into the convex portion formed by the wall surface 12 and the joint surface of the piezoelectric vibrating piece 20 by using the wall surface 12 as a guide. Therefore, the opening shape of the cap body 19 can be easily positioned. Even if there are manufacturing variations, the cap body 19 can be prevented from shifting, for example, the cap body may protrude from the outer periphery of the piezoelectric device 1 and the appearance may be poor without satisfying the dimensional specifications of the flat outer shape, or the cap may be defective. It is possible to avoid problems such as a decrease in the bonding strength and the sealing air density of the body 19. Further, according to the piezoelectric device 1 of the present embodiment using the ceramic substrate 10 having the stepped portion 11 provided on the peripheral edge portion, as compared with the case where the cap body is joined on a flat surface as in the conventional ceramic substrate. Therefore, not only the contact leg portion 19c of the cap body 19 and the step portion 11 of the ceramic substrate 10 are joined, but also the vicinity of the boundary portion between the step portion 11 of the wall surface 12 and the side wall portion 19b are joined. The bonding strength of the cap body 19 to the substrate 10 is improved, and the piezoelectric vibrating piece 20 can be reliably airtightly sealed.

Further, it is preferable that the cap body 19 is electrically connected to a ground terminal (not shown) of the ceramic substrate 10 via a metal layer 13 provided on the step portion 11 and the wall surface 12. In this way, when the piezoelectric device 1 is used, the cap body 19 made of metal is held at the ground potential, so that the piezoelectric vibrating piece 20 is subjected to unnecessary electrical action from the outside due to the shielding effect of the cap body 19. For example, it can be protected from noise.

Thus, in the piezoelectric device 1 described above, a variable voltage from the outside is applied between the excitation electrodes 25 provided on both main surfaces of the piezoelectric vibrating piece 20 via the external mounting terminal 16 provided on the bottom surface of the ceramic substrate 10. It functions as a piezoelectric device 1 by causing vibration at a predetermined frequency according to the characteristics of the piezoelectric vibration piece 20, and oscillates and outputs a reference signal of a predetermined frequency with an external oscillation circuit based on the resonance frequency of the piezoelectric device 1. can do. Then, such a reference signal can be used as a clock signal in an electronic device such as a portable communication device.

(Manufacturing method of piezoelectric device) Next, the manufacturing method of the piezoelectric device 1 having the above configuration will be described with reference to the drawings, focusing on the manufacturing method of the ceramic substrate 10. FIG. 3 is a flowchart illustrating an embodiment of a method for manufacturing the piezoelectric device 1. In addition, FIGS. 4 to 9 schematically show a process of collectively manufacturing a large number of ceramic substrates using a green sheet, and FIGS. 4, 5, and 8 are schematic plan views, FIGS. 6, 7, and 7. And FIG. 9 is a partial cross-sectional view for explaining the same cross section as in FIG. 2 in an enlarged manner.

The manufacturing process of the piezoelectric device 1 is a pre-process of preparing the piezoelectric vibrating piece 20, the ceramic substrate 10, and the cap body 19, respectively, and joining the piezoelectric vibrating piece 20 on the ceramic substrate 10 and then joining the cap body 19. It can be roughly divided into a post-process (assembly process) in which the piezoelectric vibrating piece 20 is hermetically sealed. First, in the previous steps, the preparation of the piezoelectric vibrating piece 20 and the cap body 19 will be outlined.

In the preparation of the piezoelectric vibrating piece 20 shown in step S1-1, the piezoelectric vibrating piece 20 is manufactured so that the piezoelectric device 1 can be assembled. A plurality of piezoelectric vibrating pieces 20 can be collectively formed by arranging a plurality of piezoelectric materials such as quartz on a large-sized wafer cut out to a predetermined size and polished. To explain the outline, first, a large-sized crystal substrate (quartz wafer) is prepared, which is cut out at a predetermined cut angle with respect to the crystal axis and then polished to a desired thickness and surface state. Then, the outer shapes of the plurality of piezoelectric vibrating pieces 20 are formed on the crystal substrate by wet etching using photolithography. The outer shape of the piezoelectric vibrating piece 20 is efficiently connected to the crystal wafer by a perforated cut-off portion or the like so as not to be completely separated from the crystal substrate, and the subsequent steps are efficiently performed in the crystal substrate (wafer) state. It is preferable to flow to. Then, by forming electrodes such as the excitation electrode 25 and the external connection electrode 26 by sputtering, vapor deposition, or the like, a plurality of piezoelectric vibrating pieces 20 are formed in a matrix on the crystal wafer.

In the preparation of the cap body 19 shown in step S1-3, the cap body 19 is manufactured so that the piezoelectric device 1 can be assembled. The cap body 19 is formed by forming a plate material made of a metal such as 42 alloy, Kovar, or phosphor bronze by a conventionally known sheet metal processing, so that a recess is formed in the central portion and the contact leg portion 19c is formed on the outer peripheral portion. Form a cap body 19 provided in an annular shape.

Next, the manufacturing process from the manufacturing of the ceramic substrate 10 to the assembly of the piezoelectric device 1 will be continuously described. In the present embodiment, a ceramic green sheet is used as the base material of the ceramic substrate 10, and in the production of the ceramic substrate 10, first, as shown in step S1-2, a plurality of ceramic substrates 10 are arranged in a matrix, that is, Prepare a green sheet 51 (see Fig. 4) of a size that can be formed by arranging in a matrix of m columns × n rows (n and m are natural numbers of 2 or more). In the green sheet 51 shown in FIGS. 4, 5, 8, 11, and 12, the formation region of one ceramic substrate 10 is shown as the piezoelectric device formation region 1A. The green sheet 51 can generally be obtained by uniformly placing a slurry containing ceramic powder on a film by a doctor blade method, drying the slurry, and then cutting it into a rectangular shape having a desired size. The material of the ceramic powder is not particularly limited, but alumina (Al) having excellent properties such as heat resistance, insulation resistance, abrasion resistance, and airtightness, and electrical properties.₂O₃) And aluminum nitride (AlN = aluminum nitride) can be used. In addition to the ceramic powder, an organic binder, a plasticizer, a solvent, and the like are added to the slurry, and the green sheet 51 has a relatively high plasticity at this stage when the green sheet 51 has not been fired.

Next, as shown in step S2, in each piezoelectric device forming region 1A, a through hole (via hole) for forming an in-layer wiring for energization required for conducting conduction between both main surfaces of the ceramic substrate 10. Is formed by, for example, pressing or punching. Next, as shown in step S3, the through holes formed in the ceramic substrate 10 are filled with a conductor paste containing a refractory metal such as tungsten (W) or molybdenum (Mo) by a method such as screen printing. The via hole is made conductive, and an in-layer wiring 17 that electrically connects both main surfaces of the ceramic substrate 10 is formed. Next, as shown in step S4, for example, by screen-printing a conductor paste containing a refractory metal such as tungsten or molybdenum, the vibrating piece junction terminal 18, the metal layer 13, or the wiring between terminals, the conductor pattern for plating, etc. Form the conductor pattern that is the base of the. The conductor pattern for plating is the plating voltage via the wiring between terminals when the metal plating film required for the vibrating piece junction terminal 18 and the metal layer 13 is formed by electrolytic plating in the conductor pattern plating step of step S7 described later. Refers to the plating wiring for supplying. Note that FIG. 4 shows a state in which the conductor pattern that is the base of the vibrating piece junction terminal 18 is printed on the plurality of piezoelectric device forming regions 1A of the green sheet 51, and the conductor pattern 13A that is the prototype of the metal layer 13 is further formed. (The wiring between terminals, via holes, conductor patterns for plating, etc. are not shown). The via hole conduction in step S3 and the conductor pattern printing in step S4 can be simultaneously performed by screen printing.

Next, as shown in step S5, a dividing groove provided so as to be able to be broken when the green sheet 51 is divided into individual piezoelectric devices 1 and a step portion 11 are provided by pressing with a pressing blade. (See FIGS. 5 and 6 (a) and 6 (b), but the dividing groove is not shown). The dividing groove (not shown) is formed by using a pressing blade narrower than the step portion 11 and pressing more strongly than the step portion 11 to form a deeply recessed dividing groove. The size and depth of the dividing groove shall be such that it cannot be broken by normal handling or the like, and the cutting work can be performed without difficulty (however, in the present embodiment, folding along the dividing groove). The method of individualizing the piezoelectric device by taking it is not described later, but the method of individualizing the piezoelectric device by using dicing in order to reduce the damage applied to each piezoelectric device).

Hereinafter, the formation of the step portion 11 in the step of forming the dividing groove and the step portion 11 will be described. In the formation of the step portion 11, as shown in FIG. 6A, a pressing blade 60 having both side surfaces extending outward at a predetermined inclination perpendicular to the surface that first comes into contact with the green sheet 51 is specified. Press the green sheet 51 with the pressure of. Then, as shown in FIG. 6B, a recess in the shape of the pressing blade 60 is formed by the plastic deformation of the unfired green sheet 51 having plasticity. That is, a step portion 11 parallel to the surface of the vibrating piece joining region provided with the vibrating piece joining terminal 18 of the green sheet 51 and a wall surface 12 inclined from the step portion 11 toward the surface of the vibrating piece joining region are formed. Will be done. As described above, the formation of the step portion 11 having the wall surface 12 inclined on the surface side of the vibrating piece joining region is used for forming the step portion 11 in the split groove forming step by press working included in the conventional ceramic substrate manufacturing process. By only using the pressing blade 60, it can be performed without adding a new process or equipment.

Next, as shown in step S6, the green sheet 51 on which the step portion 11 having the wall surface 12 is formed is fired at a high temperature in a reducing atmosphere to form a ceramic sheet. For example, when the ceramic powder of the green sheet 51 is alumina, it is simultaneously fired with the refractory metal of the conductor pattern at a high temperature of about 1550 ° C. The green sheet 51 described in the following steps from step S7 to completion refers to a fired green sheet 51, that is, a ceramic sheet. Next, as shown in step S7, the fired green sheet 51 is immersed in the electrolytic plating solution and energized through the above-mentioned conductor pattern for plating to expose the vibrating piece bonding terminal 18 and the metal layer 13. An electroplating film (not shown) is formed on all conductor patterns made of refractory metal. The type of the electrolytic plating film is not particularly limited, and examples thereof include an electrolytic nickel film, an electrolytic gold film, and a plurality of layers of electrolytic plating film in which nickel and gold are laminated in this order. As described above, the green sheet 51 in which a plurality of ceramic substrates 10 having the step portions 11 are formed in a matrix is completed by the steps from the preparation of the green sheet 51 in step S1-2 to steps S2 to S7 (see FIG. 5). .. At this stage, the green sheet 51 can be divided into individual ceramic substrates 10. For example, as shown in FIG. 8A, a green sheet 51 in which a plurality of piezoelectric device forming regions 1A are formed in a matrix is diced along a dicing line 75 shown by an imaginary line (dashed line) in the figure. By doing so, the individual ceramic substrate 10 shown in FIG. 8 (b) can be obtained. In the present embodiment, a method for efficiently assembling the piezoelectric device 1 while keeping the green sheet 51 in which a plurality of ceramic substrates 10 are integrally formed will be described below.

In the piezoelectric device assembly step, first, as shown in step S8, the piezoelectric vibrating piece 20 prepared in step S1-1 is joined to each piezoelectric device forming region 1A of the green sheet 51. Specifically, a joining member 39 such as silver paste is applied on the vibrating piece joining terminal 18 of each piezoelectric device forming region 1A by a dispenser or screen printing, and then provided on one end side of the piezoelectric vibrating piece 20. The external connection electrode 26 is aligned with the corresponding vibrating piece junction terminal 18 and temporarily fixed. Then, a treatment according to the curing method of the joining member 39, for example, a thermosetting type joining member 39 is heated at a predetermined temperature, and an ultraviolet curing type joining member is joined by irradiating ultraviolet rays. The member 39 is solidified and the piezoelectric vibrating piece 20 is joined in a cantilevered manner.

Next, as shown in step S9, the cap body 19 is arranged in each piezoelectric device forming region 1A of the green sheet 51 to which the piezoelectric vibrating pieces 20 are joined. In this step, the cap body 19 is fitted into the convex portion formed by the wall surface 12 formed in each piezoelectric device forming region 1A of the green sheet 51 by the step portion 11 forming step described above and the surface of the vibrating piece joining region. It can be easily aligned and arranged by inserting it. At this time, a brazing material 29 is interposed between the metal layer 13 on the surface of the step portion 11 and the wall surface 12 and the side wall portion 19b and the contact leg portion 19c of the cap body 19. As the brazing material 29, an alloy (cocrystalline alloy) such as gold-nickel (Au-Ni), gold-tin (Au-Sn) or gold-germanium (Au-Ge), or a brazing material such as solder can be used. it can. Further, low melting point glass, an adhesive used as a sealing material, or the like can also be used. The brazing material 29 may be configured such that a part thereof is provided on the metal layer 13 of the ceramic substrate 10 or at a contact portion of the cap body 19 with the ceramic substrate 10.

Next, as shown in step S10, for example, the green sheet 51 in a state where the cap body 19 and the step portion 11 and the wall surface 12 (metal layer 13) of the ceramic substrate 10 are in contact with each other via the brazing material 29, for example. The cap body 19 is joined to the ceramic substrate 10 by heating and melting the brazing material 29 in a constant temperature furnace maintained at a temperature of 300 ° C to 350 ° C. In the present embodiment, the cap body 19 made of metal is joined with the metal brazing material as the brazing material 29 to make the airtight sealing of the piezoelectric vibrating piece 20 by the cap body 19 stronger and more reliable. Can be done.

The step of joining the cap body 19 to the series of ceramic substrates 10 described above (arrangement of the cap body 19 in step S9 and joining the cap body 19 in step S10) is performed in an atmosphere of an inert gas such as nitrogen gas or argon gas, for example. , Or preferably in a reduced pressure space. As a result, the inside of the cavity T formed by the ceramic substrate 10 in which the piezoelectric vibration piece 20 is housed and the cap body 19 is filled with an inert gas, or is sealed / sealed in a reduced pressure space, so that the piezoelectric vibration It is possible to effectively prevent the piece 20 from being corroded or deteriorated by oxygen or moisture in the atmosphere. Through the series of steps described above, a plurality of piezoelectric devices 1 are formed in a matrix on the green sheet 51.

Next, as shown in step S11, the green sheet 51 that has undergone the steps up to step S10 described above is divided to obtain a plurality of pieces of piezoelectric devices 1 at the same time. The green sheet 51 is divided as shown in FIG. 6 (c) by, for example, dicing along the dicing line 75 shown in FIG. 8 by the high-speed rotating dicing blade 70 of the dicing saw shown in FIG. 6 (b). Can be cut into.

However, as shown in FIG. 6, when the metal layer 13 formed on the green sheet 51 covers the dicing line 75, when cutting the metal layer 13 and when cutting the ceramic base material of the green sheet 51. If the dicing blade 70 is not replaced, there is a risk that shape quality abnormalities such as burrs and burrs may occur on the cut surface, or the dicing blade 70 may deteriorate rapidly, resulting in a decrease in manufacturing efficiency. As a method for avoiding such a problem, after forming the dividing groove and the step portion 11 in the dividing groove / step portion forming step in step S5, the member has a pyramid-shaped cross section as shown in FIG. 7 (a). An indentation 52 is formed on the dicing line of the step 11 using the pressing blade 60B. At this time, the width of the indentation 52 is preferably the same as or slightly wider than the width of the dicing blade 70. As a result, the metal layer of the portion where the indentation 52 is formed is further rolled and becomes extremely thin. Therefore, by dicing with a dicing blade 70 suitable for dicing the base material of the green sheet 51, FIG. 7 (c) ), The green sheet 51 in which a plurality of piezoelectric devices 1 are formed can be divided on a good cut surface. Further, as a method for performing even better dicing, in the conductor pattern printing step of step S4 above, as shown in FIG. 9A, the metal layer 13 becomes the original shape while avoiding the region serving as the dicing line of the green sheet 51. Form the conductor pattern 13B. By doing so, dicing with a dicing blade 80 suitable for dicing the base material of the green sheet 51 as shown in FIG. 9 (b) is further improved as shown in FIG. 9 (c). The piezoelectric device (1) can be divided from the green sheet 51 on a straight cut surface.

The piezoelectric device 1 obtained by the dividing step is completed by inspecting the electrical characteristics and appearance quality as shown in step S12, and completes a series of manufacturing processes of the piezoelectric device 1.

According to the manufacturing method of the piezoelectric device 1 of the above embodiment, a step connected to a wall surface 12 provided on the peripheral edge of the surface of the ceramic substrate 10 on the vibrating piece bonding region side so as to be inclined toward the surface side of the vibrating piece bonding region. Part 11 is formed. As a result, the cap body 19 can be easily positioned by fitting the cap body 19 into the convex portion formed by the wall surface 12 and the joint surface of the piezoelectric vibrating piece 20 by using the wall surface 12 as a guide. Therefore, the opening shape of the cap body 19 can be easily positioned. Even if there are manufacturing variations, the cap body 19 can be prevented from shifting, for example, the cap body may protrude from the outer periphery of the piezoelectric device 1 and the appearance may be poor without satisfying the dimensional specifications of the flat outer shape, or the cap may be defective. It is possible to avoid problems such as a decrease in the bonding strength and the sealing air density of the body 19. Further, according to the piezoelectric device 1 of the present embodiment using the ceramic substrate 10 having the stepped portion 11 provided on the peripheral edge portion, as compared with the case where the cap body is joined on a flat surface as in the conventional ceramic substrate. Therefore, not only the contact leg portion 19c of the cap body 19 and the step portion 11 of the ceramic substrate 10 are joined, but also the vicinity of the boundary portion between the step portion 11 of the wall surface 12 and the side wall portion 19b are joined. The bonding strength of the cap body 19 to the substrate 10 is improved, and the piezoelectric vibrating piece 20 can be reliably airtightly sealed.

Further, in the above embodiment, an unfired green sheet 51 having plasticity is used as the material of the ceramic substrate, and a dividing groove is formed by the pressing blade 60, which is a standard step in the manufacturing process of the ceramic substrate using the green sheet. In the step, the procedure was set so that the step portion 11 was formed and then the firing was performed. Thereby, the existing equipment can be used, and the step portion 11 and the wall surface 12 of the step portion 11 can be formed relatively easily while suppressing the increase from the conventional manufacturing process.

The piezoelectric device and the method for manufacturing the piezoelectric device described in the above embodiment can also be implemented as the following modified examples.

(Modification example 1) In the method for manufacturing the piezoelectric device 1 of the above embodiment, a rectangular step portion 11 (see FIG. 5) having rounded corners in a plan view is formed on a plurality of piezoelectric device forming regions 1A of the green sheet 51. The method of collectively forming with the pressing blade 60 (see FIGS. 5 and 6) has been described. Not limited to this, a plurality of types of pressing blades may be prepared to form the shape of the step portion 11 in a plurality of times. FIG. 10 is a flowchart illustrating a modified example of a method for manufacturing a piezoelectric device in which the shape of a step portion is formed in a plurality of times. Further, FIGS. 11 and 12 are schematic plan views illustrating a process of forming a step portion on the green sheet in a plurality of times by using a plurality of types of pressing blades. For the figure of the green sheet in the state where the step portion is completed, refer to FIG. 5 used in the description of the above-described embodiment. Further, in the flowchart shown in FIG. 10 and the green sheet shown in FIGS. 11 and 12, the same components as those in the above embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the dividing groove and step portion forming step (step S5 in FIG. 3) of this modification, first, as shown in step S5-1 in FIG. 10, a square step portion is formed. Here, in this modification, a method of forming a stepped portion with a corner into two steps will be described. That is, the green sheet 51 on which the vibrating piece junction terminal 18 and the conductor pattern 13A which is the prototype of the metal layer are formed through the steps up to the conductor pattern printing step (step S4) of the manufacturing method of the piezoelectric device 1 of the above embodiment. (See FIG. 4), as shown in FIG. 11, first, a plurality of step portions 11a having an outer shape of either the vertical or horizontal step portion (11) of the plurality of piezoelectric device forming regions 1A arranged in a matrix. To form. In this modification, an example is shown in which the step portion 11a, which is the outer shape on the longitudinal side of the step portion (11) of each piezoelectric device forming region 1A, is first formed. In addition, although FIG. 11 shows an example in which four rows of step portions 11a are formed on the green sheet 51, these four rows of step portions 11a have a pressing blade having a shape capable of forming four rows of step portions 11a. It can be formed by preparing and pressing all at once. In this case, the processing time can be further shortened. Further, the four rows of step portions 11a can be formed by preparing a pressing blade having a shape capable of forming one row of step portions 11a and pressing the step portions 11a in four steps. Further, it is also possible to prepare a pressing blade capable of forming two rows of step portions 11a and to form four rows of step portions 11a in two steps. In this way, when the method of forming the step portion 11a by dividing it into a plurality of times by a pressing blade capable of forming the step portion 11a which is a divisor of the number of rows of the step portion 11a finally formed is used, pressing is performed. The blade can be used for general purposes, the pressure applied to the pressing blade during one pressing process can be reduced, and the forming position can be adjusted for each step portion 11a. It is easy to stabilize the position accuracy and shape of 11a.

Next, as shown in FIG. 12, among the vertical and horizontal outer shapes of the step portions (11) of the plurality of piezoelectric device forming regions 1A, a plurality of step portions 11b having the other outer shape different from the above-mentioned step portion 11a are formed. To do. Note that FIG. 12 illustrates an example in which four rows of stepped portions 11b formed on the green sheet 51 are formed. However, as in the case of the above-mentioned stepped portion 11a, the four rows of stepped portions 11b are represented by 4 It can also be formed by preparing pressing blades having a shape capable of forming the stepped portions 11b of the rows and pressing them all at once, and the stepped portions which are approximately the number of rows of the finally formed stepped portions 11b. With the pressing blade capable of forming 11b, it can be formed in a plurality of times.

Of the step portions (11) of each piezoelectric device forming region 1A formed on the green sheet 51 by the steps up to this point, the rectangular step portions 11a and 11b whose corners are not rounded in a plan view are as follows. In addition, as shown in step S5-2, each piezoelectric device is formed as shown in FIG. 5 by pressing using a pressing blade capable of forming each corner portion into a rounded shape in a plan view. The formation of the stepped portion 11 having a rounded corner portion in the region 1A is completed. Even in the pressing process of this step, the pressing blade having a shape capable of forming the corner portion into a rounded shape shall press all the corner portions in the green sheet 51 into a rounded shape at once. Alternatively, it may be formed in a plurality of times by a pressing blade capable of forming a part of the corner portion in the green sheet 51 into a rounded shape.

According to the manufacturing method of the piezoelectric device of the above-mentioned modification 1, when the step portion 11 is formed by press working with a pressing blade, the pressing process is performed in a plurality of times to perform one pressing process. Since the pressure applied at the time is low, the damage applied to the green sheet 51 is reduced, and the formation position can be finely adjusted for each corner portion, so that the shape can be stabilized.

(Modification example 2) In the above embodiment, the metal layer 13 is formed on the wall surface 12 of the ceramic substrate 10 from the step portion 11 to the joint surface of the piezoelectric vibrating piece 20. Not limited to this, by forming the metal layer on the wall surface with a predetermined gap from the joint surface of the piezoelectric vibrating piece 20, it is possible to avoid a problem that may occur at the time of joining the cap body. FIG. 13 shows a modification 2 of the piezoelectric device that defines the formation position of the metal layer on the wall surface, and is a partial cross-sectional view for explaining the same cross section as that of FIG. 2 in an enlarged manner. In the second modification of the piezoelectric device shown in FIG. 13, the same components as those of the piezoelectric device 1 of the above embodiment are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 13, the ceramic substrate 10 of the piezoelectric device 101 of this modified example has a stepped portion 11 on the peripheral edge of the junction surface of the piezoelectric vibration piece 20 provided with the vibration piece bonding terminal 18 in parallel with the surface of the vibration piece bonding region. Is formed. The wall surface 112 connecting the step portion 11 and the surface of the vibrating piece joining region is provided so as to be inclined from the step portion 11 to the surface side of the vibrating piece joining region. Further, a metal layer 13 is provided on the surface of the step portion 11 and on the wall surface 112. Of these, the metal layer 13 of the wall surface 112 is provided with a gap from the surface of the vibrating piece joining region.

According to the configuration of the above modification 2, since there is no metal layer 13 on the bonding surface side of the piezoelectric vibrating piece 20 of the wall surface 112, when the cap body 19 is bonded to the ceramic substrate 10 to which the piezoelectric vibrating piece 20 is bonded by brazing. In addition, it is possible to suppress the deterioration of the vibration characteristics of the piezoelectric vibrating piece 20 that may occur when the molten droplets of the brazing material 29 (wax material) made of metal or alloy are scattered on the excitation electrode 25 of the piezoelectric vibrating piece 20 or the like.

(Modification example 3) In the above-described embodiment and the modified examples 1 and 2, a mode in which the cross-sectional shape of the connecting portion between the step portion 11 of the ceramic substrate 10 and the inclined wall surfaces 12, 112 is a corner portion has been described. Not limited to this, by making the shape from the step portion to the wall surface rounded to match the shape from the side wall portion of the cap body to the contact leg portion, the mechanical strength of the piezoelectric device or the mechanical strength of the piezoelectric device can be changed. It is possible to improve the bonding strength of the cap body to the ceramic substrate. FIG. 14 shows a modification 3 of the piezoelectric device in which the shape from the step portion to the wall surface is changed, and is a partial cross-sectional view for explaining the same cross section as in FIG. 2 (and FIG. 13) in an enlarged manner. In the third modification of the piezoelectric device shown in FIG. 14, the same configurations as those of the piezoelectric device 1 of the above embodiment are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 14, the ceramic substrate 10 of the piezoelectric device 1 ́ in this modified example has a stepped portion on the peripheral edge of the joint surface of the piezoelectric vibrating piece 20 provided with the vibrating piece joint terminal 18 in parallel with the surface of the vibrating piece joint region. 11 ́ is formed. The wall surface 12 ́ connecting the step portion 11 ́ and the surface of the vibrating piece joint region is provided so as to be inclined from the step portion 11 ́ to the surface side of the vibrating piece joint region. Further, the connecting portion 111 between the step portion 11 ́ and the wall surface 12 ́ has a rounded cross-sectional shape without being angular. The rounded cross-sectional shape of the connecting portion 111 is substantially the same as the connecting portion between the side wall portion 19b and the contact leg portion 19c of the cap body 19 which is joined by abutting the step portion 11 ́ and the wall surface 12 ́. It is desirable that it is formed with roundness. Further, the shape of the rounded connecting portion 111 is connected by the rounded connecting portion 111 in the step of forming the step portion 11 ́ (the dividing groove / step portion forming step shown in step S5 of FIG. 3). It can be formed by preparing a pressing blade having a shape capable of forming the step portion 11 ́ and the wall surface 12 ́, and pressing with the pressing blade.

In an electronic device (piezoelectric device 1) having a structure in which a substrate (ceramic substrate 10) to which electronic components (piezoelectric vibrating pieces 20) are joined is hermetically sealed by a cap body 19 as in the above embodiment, the cap body 19 is made of metal. The material is often formed by well-known sheet metal processing, in which case the connecting portion that vertically connects the side wall portion 19b of the cap body 19 and the contact leg portion 19c is bent with a rounded cross-sectional shape. .. According to the piezoelectric device 1 ́ of the above modification 3, the cross-sectional shape of the connecting portion 111 connecting the step portion 11 ́ and the wall surface 12 ́ connects the side wall portion 19b of the cap body 19 and the contact leg portion 19c. It is formed with a cross-sectional shape similar to that of a connecting portion having a rounded cross-sectional shape. As a result, it is possible to suppress the occurrence of cracks and the like that may occur when stress is generated at the connection portion between the step portion 11 ́ and the wall surface 12 ́, which is the base point where the thickness of the ceramic substrate 10 becomes thin. The mechanical strength can be improved. In addition, when the cap body 19 and the ceramic substrate 10 are joined together, the parts that come into contact with each other or the parts that are close to each other become large, so that a good joining state can be easily obtained, and the operation is sealed with high air density. It is possible to provide a highly stable piezoelectric device 1 ́.

Although the embodiments of the present invention made by the inventor have been specifically described above, the present invention is not limited to the above-described embodiments and modifications thereof, and various aspects are not deviated from the gist thereof. It is possible to make changes.

For example, in the above-described embodiment and modification, an example in which the ceramic substrate 10 as a substrate is formed of a single-layer green sheet 51 has been described. Not limited to this, when a ceramic substrate is manufactured from a green sheet, it may be a multilayer substrate formed by laminating a plurality of layers of the green sheet 51 on which the conductive pattern described in the above embodiment is formed. In this case, a plurality of green sheets are prepared from the preparation of the green sheet in step S1-2 of FIG. 3 and the drilling in step S2 to the printing of the conductor pattern in step S4 described in the above embodiment, and these plurality of greens are prepared. A multilayer ceramic substrate having a step portion can be obtained by laminating and temporarily fixing the sheets, forming a dividing groove / step portion in step S5, and then firing in step S6.

Further, in the above-described embodiment and modification, the metal cap body 19 is used, and the metal layers 13, 13 ́ are provided on the step portions 11, 11 ́ and the wall surface 12, 12 ́, 112 of the ceramic substrate 10. , An example of joining the cap body 19 and the ceramic substrate 10 with a brazing material 29 made of a metal or an alloy has been described. For joining (brazing) with the brazing material, a brazing material 29 made of a metal or alloy having a melting point lower than that of the base material (cap body 19 and metal layer 13, 13 ́) is used as a joining member, and the brazing material 29 is used. Refers to a method of melting and joining, for example, in addition to the method of supplying a brazing material 29 between the contact portion between the cap body 19 and the ceramic substrate 10 before joining and melting it, the cap body It also includes a method of forming a metal or alloy layer to be a brazing material 29 on both or one of 19 and the ceramic substrate 10. Further, in the present invention, the joining member used for joining the cap body 19 and the ceramic substrate 10 is not limited to the joining member made of metal or alloy as in the above-described embodiment and modified examples, for example, low melting point glass or organic type. It also includes a configuration in which a (resin-based) adhesive is used as a joining member. In this case, the cap body 19 does not need to be made of metal, and the metal layers 13, 13 ́ need not be provided on the step portion 11, 11 ́ and the wall surface 12, 12 ́.

Further, the specific form described in the above-described embodiment and modification, for example, the shape of the ceramic substrate 10, the green sheet 51, or the piezoelectric vibrating piece 20 as an electronic component is not limited. Similarly, the positions and shapes of the electrodes, wirings, terminals, etc. are not limited to those of the above-described embodiment.

Further, in the above-described embodiment and modification, as an example of the electronic device, the piezoelectric devices 1, 1 ́, 101 equipped with the piezoelectric vibrating piece 20 as an electronic component have been described. Not limited to this, the configurations shown in the above-described embodiments and modifications are various electronic devices having a structure in which various electronic components such as semiconductor circuit elements are bonded to a substrate as electronic components and the electronic components are hermetically sealed by a cap body. Can be applied to.

1 ... Piezoelectric device as an electronic device, 1A ... Piezoelectric device formation area, 10 ... Ceramic substrate as a substrate, 11,11 ́ ... Stage, 11a ... (Part of the stage) Steps (of the green sheet), 12, 12 ́, 112 ... wall surface, 13 ... metal layer, 13A, 13B ... conductor pattern (which is the prototype of the metal layer), 16 ... external mounting Terminal, 18 ... Vibration piece joint terminal, 19 ... Cap body, 19a ... Horizontal part, 19b ... Side wall part, 19c ... Contact leg part, 20 ... Piezoelectric as an electronic part Vibration piece, 25 ... Excitation electrode, 26 ... External connection electrode, 29 ... Wax material as a joining member, 39 ... Joining member, 51 ... Green sheet as a substrate sheet, 52 .. Indentation, 60,60B ... Pressing blade, 70,80 ... Dying blade, 75 ... Dying line, 111 ... Connection part.