Wiring board, package, and piezoelectric device

Abstract

[Problem] To improve the bonding strength between a conductive bonding material used in a bonding element and a substrate. The wiring substrate includes a base portion made of a ceramic material, a frame portion, and a plurality of connection electrodes. The base portion has at least one recess that opens on a first surface of the mounting element. The connection electrodes are located on the bottom surfaces of the recesses, and the bottom surfaces of the recesses are exposed around the connection electrodes.

Description

Technical Field

[0001] This invention relates to a wiring substrate, a package, and a piezoelectric device. Background Technology

[0002] Prior art document 1 discloses a fixing structure for a crystal oscillator. In prior art document 1, in order to improve the fixing strength between the substrate and the conductive bonding material, the conductive bonding material is filled into a hole provided in the substrate and protrudes from its surface. The crystal oscillator is then fixed to the substrate by the protruding conductive bonding material.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2005-223755 Summary of the Invention

[0006] One aspect of the wiring substrate of the present invention comprises: a base made of ceramic material having a first surface including a mounting area for mounting elements; a frame portion surrounding the mounting area on the first surface; and a plurality of connecting electrodes connected to respective terminals of the elements, the base having at least one recess opening on the first surface, the connecting electrodes being located on the bottom surface of the recess, the bottom surface of the recess being exposed around the connecting electrodes.

[0007] One embodiment of the present invention has a package having the above-described wiring substrate and cover.

[0008] One aspect of the piezoelectric device of the present invention has the above-described package and piezoelectric vibrating element. Attached Figure Description

[0009] Figure 1 This is an exploded perspective view of the piezoelectric device according to Embodiment 1 of the present invention.

[0010] Figure 2 This is a top view of the wiring substrate according to Embodiment 1 of the present invention.

[0011] Figure 3 This is a cross-sectional view of the piezoelectric device according to Embodiment 1 of the present invention.

[0012] Figure 4 This is a bottom view of the wiring substrate according to Embodiment 1 of the present invention.

[0013] Figure 5 This is a partial cross-sectional view showing another embodiment of the piezoelectric device according to Embodiment 1 of the present invention.

[0014] Figure 6 This is a partial cross-sectional view showing another embodiment of the piezoelectric device according to Embodiment 1 of the present invention.

[0015] Figure 7 This is a top view showing another embodiment of the wiring substrate of the present invention.

[0016] Figure 8 This is a partial cross-sectional view showing another embodiment of the piezoelectric device according to Embodiment 1 of the present invention.

[0017] Figure 9 This is a partial cross-sectional view showing another embodiment of the piezoelectric device according to Embodiment 1 of the present invention.

[0018] Figure 10 This is a perspective view of the piezoelectric device according to Embodiment 2 of the present invention.

[0019] Figure 11 This is a top view of the wiring substrate according to Embodiment 2 of the present invention.

[0020] Figure 12 This is a cross-sectional view of the piezoelectric device according to Embodiment 2 of the present invention.

[0021] Figure 13 This is a top view of the wiring substrate according to Embodiment 3 of the present invention.

[0022] Figure 14 This is a top view of the wiring substrate according to Embodiment 4 of the present invention.

[0023] Figure 15 This is a top view of another wiring substrate according to Embodiment 4 of the present invention.

[0024] Figure 16 This is a top view of another wiring substrate according to Embodiment 4 of the present invention. Detailed Implementation

[0025] In the case of substrate thinning, the fixing structure of the crystal oscillator described in prior art document 1 may have insufficient bonding strength between the conductive bonding material and the substrate.

[0026] According to one aspect of the present invention, the bonding strength between the conductive bonding material used in the bonding element and the substrate can be improved.

[0027] [Implementation Method 1]

[0028] The wiring substrate, package, and piezoelectric device of Embodiment 1 of the present invention will be described in detail with reference to the accompanying drawings.

[0029] In the following description, the distinction between "upper" and "lower" is used for ease of explanation and does not limit the actual use of the wiring substrate, package, and piezoelectric device. In this specification, the surface of the wiring substrate on which the piezoelectric vibration element is mounted is defined as the upper surface. Furthermore, in the accompanying drawings, the positive Z-axis is considered the upper direction. The X-axis is the long axis of the wiring substrate, and the Y-axis is the axis perpendicular to both the X and Z axes. Additionally, the Z-axis is defined as the thickness direction of the wiring substrate.

[0030] Figure 1 This is an exploded perspective view of an exemplary piezoelectric device 500 of the present invention. Figure 2 This is a top view of an exemplary wiring substrate 100 of the present invention. Figure 3 This is a cross-sectional view of piezoelectric device 500. Specifically, Figure 3 Is Figure 2 The cross-sectional view of the wiring substrate 100 shown is formed by adding a piezoelectric vibration element 400 and a cover 200 to the III-III line of the cross-section. Figure 4 This is a bottom view of the wiring board 100.

[0031] like Figure 1 As shown, the piezoelectric device 500 has a package 300 and a piezoelectric vibrating element 400. The package 300 has a wiring substrate 100 and a cover 200. In practice, the wiring substrate 100 and the piezoelectric vibrating element 400 are joined via a bonding material 410, but... Figure 1 The bonding material is omitted. Additionally, the electrodes of the piezoelectric vibrating element 400 are also omitted from the diagram.

[0032] like Figure 3 As shown, the wiring substrate 100 has a base 110, a frame 140, and wiring conductors located on the surface and inside the wiring substrate 100. The planar dimensions of the package 300 of the present invention may, for example, be a long side less than or equal to 1.2 mm and a short side less than or equal to 1.0 mm, a long side less than or equal to 1.0 mm and a short side less than or equal to 0.8 mm, or a long side less than or equal to 0.8 mm and a short side less than or equal to 0.6 mm. The thickness of the package 300 of the present invention may, for example, be less than or equal to 0.2 mm, less than or equal to 0.15 mm, or less than or equal to 0.1 mm. The height of the base 110 of the present invention may, for example, be less than or equal to 0.1 mm, less than or equal to 0.075 mm, or less than or equal to 0.05 mm. The height of the frame 140 of the present invention may, for example, be less than or equal to 0.1 mm, less than or equal to 0.75 mm, or less than or equal to 0.05 mm.

[0033] When the thickness of the package 300 is 0.2 mm, the heights of the base 110, frame 140, and cover 200 can be approximately 0.08 mm, 0.07 mm, and 0.05 mm, respectively. When the thickness of the package 300 is 0.15 mm, the heights of the base 110, frame 140, and cover 200 can be approximately 0.05 mm, 0.06 mm, and 0.04 mm, respectively. When the thickness of the package 300 is 0.1 mm, the heights of the base 110, frame 140, and cover 200 can be approximately 0.03 mm, 0.04 mm, and 0.03 mm, respectively. Furthermore, in any case, the thickness of the frame-shaped metallization layer 173 described later can be approximately 0.015 mm.

[0034] Figure 2 The double-dotted line shown represents the outer edge of the piezoelectric vibrating element 400 when it is disposed on the wiring substrate 100, and is represented as an imaginary line. The mounting area 180 of the wiring substrate 100 can be the area of ​​the wiring substrate 100 that overlaps with the piezoelectric vibrating element 400 when viewed from above. That is, it can be... Figure 2 The area indicated by a double-dotted line. Alternatively, the mounting area 180 can also be the area surrounded by imaginary lines connecting the alignment marks (not shown), used when configuring the piezoelectric vibrating element 400. The mounting area 180 can be defined according to the size of the mounted piezoelectric vibrating element 400. Figure 2 For illustrative purposes, the first through conductor 171A, the second through conductor 171B, and the in-frame wiring 174 are shown in dashed lines when viewed from above. Additionally, the outer edge of the portion corresponding to the coating 110C during the fabrication of the wiring substrate 100 is also shown in dashed lines. The first through conductor 171A, the second through conductor 171B, the in-frame wiring 174, and the coating 110C will be described later.

[0035] The base 110 may be a flat insulator having a first surface 111 containing a mounting region 180 for mounting elements and a second surface 112 located opposite to the first surface 111. The base 110 may, for example, have a rectangular shape when viewed from above. The base 110 has a recess 120 that opens into the first surface 111.

[0036] The frame portion 140 surrounds the mounting area 180 and the recess 120 on the first surface 111. The wiring substrate 100 has the frame portion 140, thereby protecting the piezoelectric vibration element 400 and the like when the cover 200 is not present. The frame portion 140 can be integrally formed with the base portion 110. When viewed from above, the outer edge of the frame portion 140 can overlap with the outer edge of the base portion 110.

[0037] The base 110 and the frame 140 may also be made of insulating inorganic materials. Insulating inorganic materials include, for example, ceramic materials such as alumina sintered bodies (alumina ceramics), aluminum nitride sintered bodies, mullite sintered bodies, or glass-ceramic sintered bodies. The base 110 and the frame 140 may be integrally formed, or they may be composed of multiple stacked insulating layers or a single insulating layer.

[0038] The wiring substrate 100 has wiring conductors including a connecting electrode 150, a through conductor 171, an external electrode 172, and a frame-shaped metallization layer 173.

[0039] The connecting electrode 150 is an electrode electrically connected to the terminals of the piezoelectric vibrating element 400. In the accompanying drawings, the connecting electrode 150 is shaded in a dotted manner in the top view and perspective view.

[0040] The connecting electrode 150 is located on the bottom surface of the recess 120, and the bottom surface of the recess 120 is exposed around the connecting electrode 150. In other words, when viewed from above, the size of the connecting electrode 150 is smaller than the size of the bottom surface of the recess 120. In the thin wiring substrate 100, it is difficult to increase the depth of the recess 120 in order to ensure substrate strength. By exposing the bottom surface of the recess 120 around the connecting electrode 150, thus... Figure 3 As shown, the bonding material 410 can contact the bottom surface of the recess 120. The bonding material 410 is an example of the conductive bonding material of the present invention, such as a conductive resin. The bottom surface of the recess 120 is a ceramic surface with a surface roughness greater than that of the connecting electrode 150. Therefore, through the anchoring effect between the bonding material 410 and the bottom surface of the recess 120, the bonding strength between the bonding material 410 and the wiring substrate 100 can be improved even in wiring substrates 100 with shallow recesses 120.

[0041] The bottom surface of the recess 120 may be exposed either around at least a portion of the connecting electrode 150 or around the entire circumference of the connecting electrode 150. By exposing the bottom surface of the recess 120 around the entire circumference of the connecting electrode 150, the anchoring effect around the entire circumference of the connecting electrode 150 is improved, thereby further enhancing the bonding strength between the bonding material 410 and the wiring substrate 100.

[0042] Figure 3 The piezoelectric device 500 shown has a bonding material 410 that engages the piezoelectric vibrating element 400 and the connecting electrode 150. The bonding material 410 engages with the bottom surface of the recess 120 exposed around the connecting electrode 150. The bonding material 410 may also engage with the bottom surface of the recess 120 around the entire circumference of the connecting electrode 150. Thus, a piezoelectric device 500 can be provided that improves the bonding strength with the wiring substrate 100 through the anchoring effect between the bottom surface of the recess 120, which has a rougher surface than the connecting electrode 150, and the bonding material 410.

[0043] The connecting electrode 150 can be located in the center of the recess 120. Or, as... Figure 2 As shown, the connecting electrode 150 can also be located closer to the center of the wiring substrate 100 than the center of the recess 120. Therefore, since the distance between the connecting electrode 150 and the frame portion 140 is widened, the possibility of the bonding material 410 climbing up along the frame portion 140 can be reduced. Thus, the possibility of a short circuit between the connecting electrode 150 and the frame-shaped metallization layer 173 on the frame portion 140 can be reduced. Furthermore, the possibility of reduced adhesion between the frame-shaped metallization layer 173 and the cover 200 due to the bonding material 410 climbing up onto the frame-shaped metallization layer 173, and consequently reduced airtightness, can be reduced.

[0044] The connecting electrode 150 includes a metallization layer 151 serving as a wiring conductor and a plating layer 152 covering the metallization layer 151. The plating layer 152 may be a layer containing nickel and / or gold. For example, nickel plating can be performed on the exposed surface of the metallization layer 151, and gold plating can be performed on the nickel plating layer. This reduces the possibility of oxidation corrosion on the surface of the wiring conductor.

[0045] At least a portion of the metallization layer 151 may be embedded in the base 110. In the thinner piezoelectric device 500, it is required to improve the height accuracy related to the height of the piezoelectric vibrating element 400 (the distance between it and the first surface 111). Since the thickness accuracy of the metallization layer 151 is lower than that of the plating layer 152, the height accuracy is reduced if the metallization layer 151 is higher than the portion protruding from the base 110 (the protruding portion). Because a portion of the metallization layer 151 is embedded in the base 110, the portion protruding from the base 110 (the bottom surface of the recess 120) is reduced, thus improving the height accuracy of the piezoelectric vibrating element 400.

[0046] Furthermore, by embedding at least a portion of the metallization layer 151 in the base 110, the bonding strength with the base 110 can be improved even if the size of the metallization layer 151 is small. Also, since the portion protruding from the bottom surface of the recess 120 is reduced, the amount of bonding material 410 that can be injected into the recess 120 can be increased, thereby improving the bonding strength of the piezoelectric vibration element 400. Additionally, since the portion protruding from the bottom surface of the recess 120 is reduced, the depth of the recess 120 can be designed to be thinner, making it easier to ensure the strength of the wiring substrate 100.

[0047] The upper surface of the metallization layer 151 can be flush with the bottom surface of the recess 120. The plating layer 152 can be easily formed with high precision at a thin thickness. Because the upper surface of the metallization layer 151 is flush with the bottom surface of the recess 120, the height of the protrusion of the connecting electrode 150 from the bottom surface of the recess 120 is determined only by the thickness of the plating layer 152. Therefore, the height accuracy can be further improved by appropriately controlling the plating thickness.

[0048] In Embodiment 1, the wiring substrate 100 has two recesses 120 and two connecting electrodes 150, with each connecting electrode 150 located in a different recess 120. By having the connecting electrodes 150 located in different recesses 120, when the piezoelectric vibration element 400 is joined using the bonding material 410, the base 110 between the two recesses 120 forms a dam, which reduces the possibility of the bonding material 410 causing a short circuit.

[0049] Furthermore, in the wiring substrate 100, the inner surface of the recess 120 is flush with the inner surface of the frame 140. With this structure, since the recess 120 and the connecting electrode 150 are disposed on the outermost side within the frame 140, further miniaturization of the wiring substrate 100 is possible. Alternatively, since the recess 120 can extend into the frame 140, the bonding area between the bonding material 410 and the bottom surface of the recess 120 is increased, thereby further improving the bonding strength.

[0050] The external electrode 172 includes a first external electrode 172A and a second external electrode 172B. For example... Figure 1 and Figure 4 As shown, the first external electrode 172A and the second external electrode 172B are located on the second surface 112 of the base 110. The first external electrode 172A is an electrode electrically connected to the connecting electrode 150. The number of connecting electrodes 150 can be the same as the number of first external electrodes 172A, and each connecting electrode 150 can be connected to a different first external electrode 172A. The second external electrode 172B is an electrode electrically connected to the cover 200.

[0051] The first external electrode 172A and the second external electrode 172B can be respectively disposed at the corners of the second surface 112. For example, the first external electrode 172A and the second external electrode 172B can be located at the corners along the diagonal of the second surface 112. Alternatively, the first external electrode 172A and the second external electrode 172B can also be located at the corners along the short side direction (Y direction) of the wiring substrate 100. The first external electrode 172A and the second external electrode 172B can extend from the second surface 112 of the base 110 to the side surfaces (including the corners between the side surfaces).

[0052] Since both the first external electrode 172A and the second external electrode 172B are located on the second surface 112 of the base 110, the package 300 and the piezoelectric device 500 can be surface-mounted on the mounting substrate.

[0053] The first through conductor 171A is a wiring that penetrates the base 110 and connects the connecting electrode 150 to the first external electrode 172A. The second through conductor 171B and the in-frame wiring 174 are wirings that connect the frame-shaped metallization layer 173 to the second external electrode 172B. In other words, the frame-shaped metallization layer 173 is connected to the second external electrode 172B via the in-frame wiring 174 and the second through conductor 171B. The second through conductor 171B extends along the Z-axis in the base 110 and connects the second external electrode 172B to the in-frame wiring 174. The in-frame wiring 174 is located inside the base 110 and inside the frame portion 140, and connects the second through conductor 171B to the frame-shaped metallization layer 173.

[0054] The frame-shaped metallization layer 173 is a conductive layer located on the upper surface of the frame portion 140. The frame-shaped metallization layer 173 is bonded to the cover 200 using a sealing material (not shown) such as gold-tin alloy (AuSn) or silver wax.

[0055] Similar to the connecting electrode 150, the exposed surfaces of the frame-shaped metallization layer 173 and the outer electrode 172 can also be covered with a nickel and / or gold plating. By covering the frame-shaped metallization layer 173 with plating, the connection between the frame-shaped metallization layer 173 and the cover 200, which is a metal conductor, can be made easy and secure. By covering the outer electrode 172 with plating, the connection between it and the electrodes of the mounting substrate on which the piezoelectric device 500 is mounted can be made easy and secure.

[0056] The piezoelectric vibrating element 400 can be an AT-cut crystal vibrating element, an SC-cut crystal vibrating element, a BT-cut crystal vibrating element, or other crystal vibrating elements. Furthermore, the piezoelectric vibrating element 400 can be a stepped or inverted mesa type, where the area of ​​the vibrating portion on its lower surface side is above the bonding area with the bonding material 410. When the piezoelectric vibrating element 400 is a stepped or inverted mesa type, even if the wiring substrate 100 warps, the possibility of the vibrating portion contacting the wiring substrate 100 can be reduced.

[0057] The cover 200, for example, is made of a conductive metal and, through bonding with the frame-shaped metallization layer 173, provides an hermetically sealed enclosure 300. The cover 200 can, for example, be made of an iron-nickel alloy or an iron-nickel-cobalt alloy. The cover 200 can be formed into a specified shape using conventional metal processing methods such as rolling and punching. The cover 200 can be grounded. More specifically, by grounding through the second external electrode 172B, the cover 200 can obtain a ground potential. Grounding the cover 200 reduces the propagation of external noise into the enclosure 300.

[0058] (Manufacturing method of wiring substrate)

[0059] Next, an example of a method for manufacturing the wiring substrate 100 will be described.

[0060] First, through holes are formed on the ceramic green sheet constituting the base 110 and the frame 140, and conductors are injected to form a first through conductor 171A and a second through conductor 171B.

[0061] Then, using a mask, metallizing paste is applied to the positions of the connecting electrode 150, the in-frame wiring 174, and the frame-shaped metallization layer 173 on the upper surface of the ceramic green sheet. The frame-shaped metallization layer 173 can also be formed by applying metallizing paste to the upper surface of the frame portion 140 after forming the frame portion 140 with a pressure fixture, as described later. Next, within an appropriate area covering the portion of the metallizing paste corresponding to the in-frame wiring 174, ceramic paste (coating 110C) of the same material as the ceramic green sheet is applied using a mask.

[0062] On the lower surface of the ceramic green sheet, metallizing paste is applied to each location of the external electrodes 172 using a mask. Furthermore, on the lower surface of the ceramic green sheet, metallizing paste is applied to the locations of internal wiring (not shown) that connects the wiring to each external electrode 172. Additionally, ceramic paste is applied to the lower surface of the ceramic green sheet, covering the internal wiring connecting the external electrodes 172. The application of metallizing paste and ceramic paste is performed, for example, by screen printing.

[0063] A ceramic green sheet coated with metallizing paste on both sides is placed on a flat plate, and pressure is applied from the top surface using a pressure jig with concave and convex shapes corresponding to the frame portion 140, the recess 120, and the connecting electrode 150. This forms the frame portion 140, the recess 120, and the connecting electrode 150 located on the bottom surface of the recess 120. In this pressure application process, if the connecting electrode 150 is embedded flush with the bottom surface of the recess 120, a wiring substrate 100 with a metallization layer 151 of the connecting electrode 150 flush with the bottom surface of the recess 120 can be fabricated with high precision.

[0064] The in-frame wiring 174 in the metallizing paste is embedded between the coating 110C and the ceramic green sheet. The upper end of the second through conductor 171B is pressed downward by the metallizing paste and coating 110C that constitute the in-frame wiring 174.

[0065] On the lower surface of the ceramic green sheet, metallizing paste and ceramic paste are planarized to form external electrodes 172 connected via internal wiring. Next, a wiring substrate 100 is obtained by sintering at a temperature of 1300–1600°C. Subsequently, electroplating, mounting of the piezoelectric vibrating element 400, and joining of the cover 200 are performed as needed, thereby obtaining the piezoelectric device 500.

[0066] Alternatively, the wiring substrate 100 can be manufactured as follows: A plurality of ceramic green sheets are fabricated, each having a frame portion 140, a recess 120, and through holes for conductors at appropriate locations. Then, conductor injection, metallization paste application, and lamination are performed, followed by sintering at a temperature of 1300°C to 1600°C. Alternatively, the base portion 110 and frame portion 140 can be fabricated by laminating a plurality of ceramic green sheets with through holes, and the recess 120 can be formed using a pressure fixture. The recess 120 can be formed using a mold while the ceramic green sheets are still in the state before lamination, or it can be formed during lamination using a lamination mold, or it can be formed by pressure using a mold after lamination.

[0067] (Other configurations of wiring board 100 and piezoelectric device 500)

[0068] Figure 5 This is a partial cross-sectional view showing another configuration of the piezoelectric device 500, illustrating an example where the bonding material 410 also engages with the inner wall of the recess 120. (See also...) Figure 5 As shown, in the piezoelectric device 500, in addition to the bottom surface of the recess 120, the bonding material 410 can also be bonded to the inner surface of the recess 120. This further enhances the bonding strength between the bonding material 410 and the wiring substrate 100.

[0069] Figure 6 This is a partial cross-sectional view showing another embodiment of the piezoelectric device 500, illustrating an example where the connecting electrode 150 is located adjacent to the inner wall of the recess 120. (See also...) Figure 6 As shown, in the wiring substrate 100, the bottom surface of the recess 120 does not need to be exposed around the entire circumference of the connecting electrode 150; only a portion needs to be exposed. Furthermore, when the distance between the connecting electrode 150 and the inner wall of the recess 120 is extremely small, or when they are in contact, a portion of the bonding material 410 can be bonded to the first surface 111 of the base 110 adjacent to that inner wall. Therefore, bonding of the bonding material 410 and the base 110 can be achieved around the entire circumference of the connecting electrode 150, further improving the bonding strength.

[0070] Figure 7 This is a top view of the wiring substrate 100A. The position and planar shape of the recess 120A of the wiring substrate 100A are different from those of the recess 120 of the wiring substrate 100. Other aspects may have the same structure as the wiring substrate 100 of Embodiment 1.

[0071] Specifically, when viewed from above, the recess 120A of the wiring substrate 100A is located at a position separate from the frame portion 140. By positioning the recess 120A at a position separate from the frame portion 140, the possibility of the bonding material 410 climbing up the frame portion 140 can be reduced.

[0072] Furthermore, when viewed from above, the recess 120A is polygonal, and at least one corner between adjacent inner surfaces has a curved shape. In other words, when viewed from above, at least one corner of the recess 120A has a curved shape. When viewed from above, the recess 120A can be rectangular, triangular, pentagonal, hexagonal, parallelogram, rhombus, etc. By having a curved shape at the corner between adjacent inner surfaces, the possibility of cracks originating from the corners can be reduced compared to a configuration where the corners at the boundaries of the inner surfaces are right angles. Additionally, the thermal stress applied when the cover 200 is joined to the wiring substrate 100A or when the piezoelectric device 500 is mounted to the mounting substrate tends to increase at the corners of the wiring substrate 100A. Therefore, the corners of the recess 120A near the corners of the wiring substrate 100A can also be configured with a curved shape.

[0073] The corner of the recess 120A that has a curved shape can be the corner located inside the base 110 when viewed from above. In other words, the corner between the two inner surfaces of the recess 120 located inside the base 110 can have a curved shape. As with the wiring substrate 100A, if the recesses 120A are adjacent along one side of the base 110, the distance between the recesses 120A is shorter in the miniaturized wiring substrate 100A. By making the corner located inside the base 110 curved, the possibility of cracks starting from the corner between the recesses 120A can be reduced. In the above-described manufacturing method using a pressure fixture, by changing the shape of the pressure fixture, it is easy to form rounded corners between the inner surfaces.

[0074] Figure 8 This is a partial cross-sectional view of the piezoelectric device 500B. The wiring substrate 100B of the piezoelectric device 500B has a recess 120B. (As shown...) Figure 8As shown in the example, the corner between the inner side surface and the bottom surface of the recess 120B can have a curved shape. Compared to a corner where the inner side surface and the bottom surface are right angles, this type of wiring substrate 100B can reduce the possibility of cracks originating from the corner. In the manufacturing method using the pressure fixture described above, by changing the shape of the pressure fixture, it is easy to form rounded corners between the inner side surfaces. The top view shape of the recess 120B is not particularly limited; for example, it can be circular or polygonal.

[0075] Furthermore, the corner between the inner side of the frame portion 140 and the first surface 111 of the base portion 110 can also be curved. This reduces the possibility of cracks originating from this corner. In the manufacturing method using the pressure clamp described above, not only the shape of the recess 120B, but also the shape of the frame portion 140 can be easily formed by changing the shape of the pressure clamp.

[0076] Figure 9 This is a partial cross-sectional view of the piezoelectric device 500C. The wiring substrate 100C of the piezoelectric device 500C has a recess 120C. (As shown...) Figure 9 As shown in the example, the angle between the inner side surface and the bottom surface of the recess 120C can be an obtuse angle. Compared to a right angle between the inner side surface and the bottom surface, this wiring substrate 100C can reduce the possibility of cracks originating from the corner. Furthermore, the angle between the inner side surface and the bottom surface of the recess 120C is obtuse, and the corner between the inner side surface and the bottom surface can have a curved shape. This further reduces the possibility of crack formation. In the above-described manufacturing method using a pressure fixture, by changing the shape of the pressure fixture, it is easy to form a recess 120C with an obtuse angle between the inner side surface and the bottom surface.

[0077] exist Figure 9 The diagram shows an example where the inner surface of the recess 120C is flush with the inner surface of the frame 140, and the angle between the inner surface of the frame 140 and the first surface 111 of the base 110 is also an obtuse angle. Alternatively, the surface from the recess 120C to the first surface 111 can be inclined, and the angle between the frame 140 and the first surface 111 can be a right angle. Furthermore, the angles between the inner surface of the recess 120C and the bottom surface, and the angle between the frame 140 and the first surface 111, can be obtuse angles of different angles. In the above-described manufacturing method using a pressure fixture, such a shape can be easily formed by changing the shape of the pressure fixture. This structure also reduces the possibility of cracks originating from the corner between the inner surface and the bottom surface.

[0078] [Implementation Method Two]

[0079] The second embodiment of the present invention will now be described. For ease of explanation, components having the same function as those described in the above embodiments will be labeled with the same reference numerals and will not be described again.

[0080] Figure 10 This is a perspective view of the piezoelectric device 500D according to Embodiment 2. Figure 11 This is a top view of the wiring substrate 100D according to Embodiment 2. Figure 12 This is a cross-sectional view of the piezoelectric device 500D. Specifically, Figure 12 Is Figure 11 The cross-sectional view of the wiring substrate 100D shown is formed by adding a piezoelectric vibration element 400 and a cover 200 to the XII-XII line of the cross-section.

[0081] The piezoelectric device 500D has a wiring substrate 100D. The wiring substrate 100D differs from the wiring substrate 100 of Embodiment 1 in the position of the two recesses 120D. Other aspects may have the same structure as the wiring substrate 100 of Embodiment 1.

[0082] like Figure 10 and Figure 11 As shown in the example, the two recesses 120D in the wiring substrate 100D can be located at opposite corners along the diagonal of the wiring substrate 100D (or base 110). In other words, the two recesses 120D can also be located at opposite corners of the first surface 111 of the base 110, which is rectangular when viewed from above. According to this structure, since the distance between the recesses 120D is increased, the possibility of cracks forming between the recesses 120D can be reduced. In addition, in the wiring substrate 100D, the positions of the recesses 120D, which have a thinner substrate thickness, are evenly distributed within the substrate, thus increasing the substrate strength and reducing substrate warping. Furthermore, if the corners between the inner surfaces of the recesses 120D when viewed from above are made into a curved shape, the possibility of cracks forming in the wiring substrate 100D can be further reduced (see reference). Figure 15 ).

[0083] [Implementation Method 3]

[0084] Figure 13 This is a top view of the wiring substrate 100E according to Embodiment 3. The wiring substrate 100E differs from the wiring substrate 100 of Embodiment 1 in that the two connecting electrodes 150 are located on the bottom surface of a recess 120E. The length of the recess 120E in the Y-axis direction of the wiring substrate 100E is greater than the length of the piezoelectric vibrating element 400 in the Y-axis direction. Since the two connecting electrodes 150 are located adjacent to each other, it can be used, for example, as a substrate for mounting a stepped piezoelectric vibrating element 400. Furthermore, since there is only one recess 120E in the wiring substrate 100E, there is no situation where cracks occur between the corners of the recesses when they are adjacent.

[0085] [Implementation Method Four]

[0086] exist Figures 14-16 In this paper, an example of a wiring board having a pillow portion that supports a piezoelectric vibrating element 400 will be described. Figure 14 This is a top view of the wiring board 100F. Figure 15 This is a top view of the 100G wiring board. Figure 16 This is a top view of the wiring board 100H.

[0087] Figure 14 The wiring substrate 100F shown has a pillow portion 130. The wiring substrate 100F has two recesses 120 along one side of the first surface 111. The pillow portion 130 is an insulator that is U-shaped when viewed from above and protrudes relative to the first surface 111. The outer edge of the pillow portion 130 may be adjacent to or joined to the frame portion 140.

[0088] The height of the pillow portion 130 can be approximately the same as the height of the upper surface of the connecting electrode 150. Alternatively, the height of the pillow portion 130 can be approximately the same as the height obtained by adding the thickness of the connecting electrode 150 and the bonding material 410.

[0089] The pillow portion 130 can be made of an insulating inorganic material. Insulating inorganic materials include, for example, ceramics such as alumina sintered bodies (alumina ceramics), aluminum nitride sintered bodies, mullite sintered bodies, or glass-ceramic sintered bodies. The base portion 110, the pillow portion 130, and the frame portion 140 can be integrally formed, or they can be composed of a plurality of laminated insulating layers or a single insulating layer.

[0090] Since the pillow portion 130 is joined to the first surface 111 and the frame portion 140, the strength of the wiring board 100F can be improved.

[0091] Figure 15 The wiring board 100G shown has a pillow portion 130A, a pillow portion 130B, and a pillow portion 130C. The pillow portion 130A is inscribed in the corner of the frame portion 140 and is rectangular. The pillow portion 130B is inscribed in any side of the frame portion 140 and is rectangular. The pillow portion 130C is inscribed in the corner of the frame portion 140 and is L-shaped along the corner.

[0092] The wiring substrate 100G does not need to have all the pillow portions 130A, 130B, and 130C; any one of them can be present in multiples. Alternatively, the pillow portions 130A, 130B, or 130C can be arbitrarily combined. Since the pillow portion 130 of the wiring substrate 100G is joined to the first surface 111 and the frame portion 140, the strength of the wiring substrate 100F can be improved.

[0093] Figure 16The wiring substrate 100H shown has a pillow portion 130D and a pillow portion 130E. The pillow portion 130D is located at a corner of the wiring substrate 100H, separated from the frame portion 140, and has a shape that protrudes relative to the first surface 111. The pillow portion 130D can be made of an insulator or a metallization layer. The pillow portion 130E is a pillow portion formed such that the coating 110C described in Embodiment 1 protrudes relative to the first surface 111. Alternatively, the coating 110C may not be covered by the in-frame wiring 174, and a portion of the in-frame wiring 174 that protrudes relative to the first surface 111 may be used as a pillow portion. By using a portion of the in-frame wiring 174 connected to the ground electrode as a pillow portion, it is possible to reduce the charge on the components.

[0094] 〔Summarize〕

[0095] The wiring substrate of one embodiment of the present invention comprises: a base made of ceramic material having a first surface including a mounting area for mounting elements; a frame portion surrounding the mounting area on the first surface; and a plurality of connecting electrodes connected to respective terminals of the elements, the base having at least one recess opening on the first surface, the connecting electrodes being located on the bottom surface of the recess, and the bottom surface of the recess being exposed around the connecting electrodes.

[0096] The wiring substrate of the second embodiment of the present invention is the same as that of the first embodiment described above. The connection electrode includes a metallization layer as a wiring conductor and a plating layer covering the metallization layer. At least a portion of the metallization layer is embedded in the base.

[0097] In the wiring substrate of the third embodiment of the present invention, the upper surface of the metallization layer is flush with the bottom surface of the recess as described in the second embodiment.

[0098] The wiring substrate of the fourth embodiment of the present invention is in any of the embodiments one to three above, wherein the number of connecting electrodes is two, the base has two recesses, and the two connecting electrodes are respectively located in different recesses.

[0099] The wiring substrate of the fifth embodiment of the present invention is the same as that of the fourth embodiment described above, wherein the base has a rectangular shape when viewed from above, and the two recesses are located at opposite corners along the diagonal of the base.

[0100] The wiring substrate of the sixth embodiment of the present invention is in any of the embodiments one to five described above, wherein at least one inner side surface of the recess and the corner between the bottom surface are curved.

[0101] In the wiring substrate of embodiment seven of the present invention, in any of the embodiments one to five described above, the angle formed between at least one inner side surface of the recess and the bottom surface is an obtuse angle.

[0102] The wiring substrate of Embodiment 8 of the present invention is an example of Embodiment 6, wherein the angle between at least one inner side surface of the recess and the bottom surface is an obtuse angle.

[0103] In the wiring substrate of embodiment nine of the present invention, in any of the embodiments one to eight above, the recess is polygonal when viewed from above, and the corners between adjacent inner surfaces of the recess are curved.

[0104] The wiring substrate of the tenth embodiment of the present invention is the same as that of the ninth embodiment described above, wherein the adjacent inner sides are two inner sides located inside the base.

[0105] In the wiring substrate of embodiment eleven of the present invention, in any of the embodiments one to ten described above, at least one inner side surface of the recess is flush with the inner surface of the frame portion.

[0106] The wiring substrate of embodiment 12 of the present invention is in any of the embodiments 1 to 10 described above, wherein the recess is located at a position separate from the frame portion.

[0107] The wiring substrate of embodiment thirteen of the present invention is in any of the embodiments one to twelve described above, wherein the bottom surface of the recess is exposed around the entire circumference of the connecting electrode.

[0108] The package of embodiment fourteen of the present invention has a wiring substrate and a cover as described in any of embodiments one to thirteen above.

[0109] The piezoelectric device of embodiment 15 of the present invention has the package and piezoelectric vibration element described in embodiment 14 above.

[0110] The piezoelectric device of embodiment sixteen of the present invention is the same as that of embodiment fifteen above, having a conductive bonding material for joining the piezoelectric vibrating element and the connecting electrode, the conductive bonding material being bonded to at least a portion of the bottom surface exposed around the connecting electrode.

[0111] The invention disclosed herein has been described above with reference to the accompanying drawings and embodiments. However, the invention disclosed herein is not limited to the embodiments described above. That is, the invention disclosed herein can be modified in various ways within the scope shown in this disclosure, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included within the technical scope of the invention disclosed herein. In other words, those skilled in the art should note that various modifications or alterations can be easily made according to the present invention. Furthermore, it should be noted that these modifications or alterations are included within the scope of the present invention.

[0112] Explanation of reference numerals in the attached figures

[0113] Wiring substrates 100, 100A, 100B, 100C, 100D, 100E, 100F, 100G, 100H

[0114] 110 Base

[0115] 120, 120A, 120B, 120C, 120D, 120E concave part

[0116] 130, 130A, 130B, 130C, 130D, 130E (Occipital region)

[0117] 140 frame

[0118] 150 Connecting Electrodes

[0119] 151 Metallization layer

[0120] 171 Through conductor

[0121] 171A First Through Conductor

[0122] 171B Second Through Conductor

[0123] 172 External Electrode

[0124] 172A First External Electrode

[0125] 172B Second External Electrode

[0126] 173 Frame-shaped metallization layer

[0127] 174 Wiring within the frame

[0128] 180 Loading Area

[0129] 200 Cover

[0130] 300 package

[0131] 400 piezoelectric vibration element

[0132] 410 Bonding Material

[0133] 500, 500B, 500C, 500D piezoelectric devices

Claims

1. A wiring substrate, wherein, have: The base is made of ceramic material and has a first surface that includes a mounting area for mounting elements; The frame portion surrounds the mounting area on the first surface; and A plurality of connecting electrodes are connected to various terminals of the component. The base has at least one recess that opens on the first surface. The connecting electrodes are located on the bottom surface of the recess. The bottom surface of the recess is exposed around the connecting electrode.

2. The wiring substrate according to claim 1, wherein, The connection electrode includes a metallization layer serving as a wiring conductor and a plating layer covering the metallization layer. At least a portion of the metallization layer is embedded in the base.

3. The wiring substrate according to claim 2, wherein, The upper surface of the metallized layer is flush with the bottom surface of the recess.

4. The wiring substrate according to any one of claims 1 to 3, wherein, The number of connecting electrodes is two. The base has two recesses. The two connecting electrodes are located in different recesses.

5. The wiring substrate according to claim 4, wherein, The base has a rectangular shape when viewed from above, and the two recesses are located at opposite corners along the diagonal of the base.

6. The wiring substrate according to any one of claims 1 to 5, wherein, At least one inner side of the recess is curved at the corner between the inner side and the bottom surface.

7. The wiring substrate according to any one of claims 1 to 5, wherein, The angle between at least one inner side surface of the recess and the bottom surface is an obtuse angle.

8. The wiring substrate according to claim 6, wherein, The angle between at least one inner side surface of the recess and the bottom surface is an obtuse angle.

9. The wiring substrate according to any one of claims 1 to 8, wherein, The recess is polygonal when viewed from above. The corners between adjacent inner surfaces of the recess are curved.

10. The wiring substrate according to claim 9, wherein, The adjacent inner surfaces are the two inner surfaces located inside the base.

11. The wiring substrate according to any one of claims 1 to 10, wherein, At least one inner side of the recess is flush with the inner surface of the frame.

12. The wiring substrate according to any one of claims 1 to 10, wherein, The recess is located separately from the frame.

13. The wiring substrate according to any one of claims 1 to 12, wherein, The bottom surface of the recess is exposed around the entire circumference of the connecting electrode.

14. An encapsulation, wherein, have: The wiring substrate according to any one of claims 1 to 13; and Cover body.

15. A piezoelectric device, wherein, have: The package as claimed in claim 14; and Piezoelectric vibration element.

16. The piezoelectric device according to claim 15, wherein, The material having a conductive bonding element for joining the piezoelectric vibration element and the connecting electrode The conductive bonding material bonds to at least a portion of the bottom surface exposed around the connecting electrode.

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