Wiring board and electronic device

Abstract

The present invention improves the flatness of a component mounting surface of a heat dissipation member to improve the connection reliability between a wiring substrate and an electronic component. The wiring substrate is provided with: a wiring conductor positioned from a first surface of an insulating substrate to a second surface; a frame-shaped metal layer that is positioned on the bottom surface of a recess of the insulating substrate and surrounds a through-hole; and, the heat dissipation member, which is positioned inside the recess of the insulating substrate so as to close the through-hole, bonded to the frame-shaped metal layer by a brazing material, and has the component mounting surface on the through-hole side. The frame-shaped metal layer has a protrusion that protrudes to the heat dissipation member side, the protrusion being positioned so as to overlap the heat dissipation member in planar perspective.

Description

Technical Field

[0001] The present disclosure relates to a wiring board and an electronic device.

Background Art

[0002] In recent years, various developments have been made in electronic devices including a wiring board and electronic components mounted on the wiring board. The wiring board described in Patent Document 1 includes an insulating substrate having through holes and a heat dissipation member (heat radiator in Patent Document 1) positioned so as to block the through holes in the insulating substrate. The heat dissipation member is joined to the peripheral portion of the through hole in the insulating substrate by a bonding material. The heat dissipation member has a component mounting surface for mounting an electronic component (electronic element in Patent Document 1) on the through hole side of the insulating substrate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] The wiring board according to the present disclosure includes an insulating substrate having a first surface, a second surface located on the opposite side of the first surface, a recess opening to the second surface, and a through hole penetrating from the bottom surface of the recess to the first surface, a wiring conductor located from the first surface to the second surface, a frame-shaped metal portion located on the bottom surface of the recess and surrounding the through hole, and a heat dissipation member located in the recess so as to block the through hole, joined to the frame-shaped metal portion by a brazing material, and having a component mounting surface on the through hole side. The frame-shaped metal portion has a convex portion protruding toward the heat dissipation member side, and the convex portion is positioned so as to overlap the heat dissipation member in a plan view.

[0005] The electronic device according to the present disclosure includes the wiring board and an electronic component mounted on the component mounting surface of the heat dissipation member, located in the through hole, and electrically connected to the wiring conductor.

Brief Description of the Drawings

[0006]

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Mode for Carrying Out the Invention

[0007] In the manufacturing process of the electronic device, when joining the heat radiating member to the peripheral portion of the through hole in the insulating substrate, the bonding material may flow to the component mounting surface side of the heat radiating member. In such a case, there is a concern that the flatness of the component mounting surface of the heat radiating member may deteriorate. In the wiring board and the electronic device of the present disclosure, the flatness of the component mounting surface of the heat radiating member can be improved.

[0008] Hereinafter, the wiring board and the electronic device according to the embodiment will be described in detail with reference to the drawings. However, each of the drawings referred to below shows only the components necessary for explaining the embodiment in a simplified manner for convenience of explanation. Therefore, the wiring board and the electronic device according to the embodiment may include any components not shown in each of the drawings referred to. Also, the dimensions of the components in each drawing do not necessarily faithfully represent the dimensions of the actual components and the dimensional ratios of each member. In the present disclosure, the rectangular shape is not limited to a strict rectangular shape, and includes, for example, a shape in which the corners are curved but can be visually recognized as a rectangular shape as a whole. In the drawings of the present disclosure, in addition to hatching the cross-sectional portions, dots are attached to the surfaces of the conductor portions, the surfaces of the electronic components, the surfaces of the heat dissipation members, and the surfaces of the brazing materials.

[0009] 〔Embodiment 1〕 Embodiment 1 will be described with reference to FIGS. 1 to 9. FIG. 1 is a schematic perspective view of the electronic device according to Embodiment 1, showing a state in which the lid body is removed. FIG. 2 is a schematic plan view of the electronic device shown in FIG. 1. FIG. 3 is a schematic bottom view of the electronic device shown in FIG. 1. FIG. 4 is a schematic cross-sectional view of the electronic device shown in FIG. 1. FIG. 5 is a schematic perspective view of the wiring board according to Embodiment 1 as viewed from the insulating frame side. FIG. 6 is a schematic perspective view of the wiring board shown in FIG. 5 as viewed from the second surface side of the insulating substrate. FIG. 7 is a schematic perspective view of the wiring board shown in FIG. 5 as viewed from the second surface side of the insulating substrate, showing a state in which the heat dissipation member is removed. FIG. 8 is a schematic bottom view of the wiring board shown in FIG. 5, showing a state in which the heat dissipation member is removed. FIG. 9 is a schematic cross-sectional view showing a state in which the electronic device shown in FIG. 1 is mounted on a mother board.

[0010] As shown in FIGS. 1 to 4, the electronic device 200 according to Embodiment 1 includes the wiring board 1 according to Embodiment 1 and electronic components 300 mounted on the wiring board 1. The wiring board 1 according to Embodiment 1 includes an insulating substrate 2. The insulating substrate 2 is made of ceramics such as, for example, an aluminum oxide sintered body (alumina ceramics), an aluminum nitride sintered body, a mullite sintered body, or a glass-ceramics sintered body. The insulating substrate 2 is composed of a plurality of insulating layers.

[0011] As shown in FIGS. 1, 2, 4, 5, and 6, the insulating substrate 2 has a first surface 2a, a second surface 2b located on the opposite side of the first surface 2a, a recess 21 opening in the second surface 2b, and a rectangular through hole 22 penetrating from the bottom surface of the recess 21 to the first surface 2a. The recess 21 of the insulating substrate 2 is rectangular in plan view, and the size of the recess 21 of the insulating substrate 2 is larger than the through hole 22 of the insulating substrate 2. The through hole 22 of the insulating substrate 2 is rectangular in plan view and is a hole for accommodating the electronic component 300. The inner peripheral surfaces of the recess 21 and the through hole 22 of the insulating substrate 2 are respectively parallel to the thickness direction of the insulating substrate 2. The shape of the recess 21 of the insulating substrate 2 in plan view and the shape of the through hole 22 in plan view are not limited to rectangular shapes, and may be shapes other than rectangular shapes such as, for example, circular shapes.

[0012] As shown in FIGS. 1, 4, and 5, the wiring board 1 includes an insulating frame body 3 located on the first surface 2a of the insulating substrate 2. The insulating frame body 3 is integrated with the insulating substrate 2 and is made of the same material as the insulating substrate 2. The insulating frame body 3 is composed of one or a plurality of insulating layers. Further, the insulating frame body 3 has a through hole 31, and the through hole 31 has a stepped portion 32 on the opening side. The through hole 31 of the insulating frame body 3 communicates with the through hole 22 and the recess 21 of the insulating substrate 2. The stepped portion 32 of the through hole 31 of the insulating frame body 3 is rectangular in plan view, and the portion of the through hole 31 of the insulating frame body 3 excluding the stepped portion 32 is circular in plan view. The size of the through hole 31 of the insulating frame body 3 is larger than that of the through hole 22 of the insulating substrate 2. The insulating frame body 3 may not have the stepped portion 32. The plan view shape of the through hole 31 of the insulating frame body 3 is not limited to the above-described shape and may be changed as appropriate.

[0013] As shown in FIGS. 2, 3, and 4, the wiring board 1 includes wiring conductors for electrically connecting the electronic component 300 and the mother board 400. The wiring conductors include, for example, a first wiring conductor 4 and a second wiring conductor 5. The first wiring conductor 4 is located from the first surface 2a to the second surface 2b of the insulating substrate 2. The first wiring conductor 4 has a first electrode 41 located on the first surface 2a of the insulating substrate 2, a first external electrode 42 located on the second surface 2b of the insulating substrate 2, and a first connection wiring 43 located inside the insulating substrate 2 and electrically connecting the first electrode 41 and the first external electrode 42. The first electrode 41 and the first external electrode 42 are wiring layers located on the surface of the insulating substrate 2. The first connection wiring 43 is a through-conductor that penetrates two insulating layers. The first connection wiring 43 may have two through-conductors that penetrate each of the two insulating layers and a wiring layer located between the insulating layers and connecting the through-conductors to each other. The second wiring conductor 5 is also located from the first surface 2a to the second surface 2b of the insulating substrate 2. The second wiring conductor 5 has a second electrode 51 located on the first surface 2a of the insulating substrate 2, a second external electrode 52 located on the second surface 2b of the insulating substrate 2, and a second connection wiring 53 electrically connecting the second electrode 51 and the second external electrode 52. The second electrode 51 and the second external electrode 52 are wiring layers of the second wiring conductor 5. The second connection wiring 53 is a through-conductor that penetrates two insulating layers. The second connection wiring 53 may have two through-conductors that penetrate each of the two insulating layers and a wiring layer located between the insulating layers and connecting the through-conductors to each other.

[0014] The wiring conductors (the first wiring conductor 4 and the second wiring conductor 5) are made of metal powder metallization containing components such as tungsten (W), molybdenum (Mo), manganese (Mn), silver (Ag), or copper (Cu).

[0015] As shown in FIG. 9, the first electrode 41 is electrically connected to the first electrode of the electronic component 300 by, for example, a bonding wire W. The first external electrode 42 is electrically connected to the first electrode 410 of the mother board 400 via a solder S. Also, the second electrode 51 is electrically connected to the second electrode of the electronic component 300 by, for example, a bonding wire W. The second external electrode 52 is electrically connected to the second electrode 420 of the mother board 400 via a solder S.

[0016] The number, configuration, shape, arrangement, etc. of the wiring conductors are not limited to the above example, and can be appropriately changed according to the number, arrangement, etc. of the first and second electrodes of the electronic component 300 to be mounted.

[0017] As shown in FIGS. 4, 7, and 8, the wiring board 1 includes a frame-shaped metal layer 6 as a frame-shaped metal portion located on the bottom surface of the recess 21 of the insulating substrate 2. The frame-shaped metal layer 6 surrounds the through-hole 22 of the insulating substrate 2. The frame-shaped metal layer 6 is made of the same metal powder metallization as the first wiring conductor 4 and the second wiring conductor 5.

[0018] The bottom view shape of the frame-shaped metal layer 6 may be the same as the bottom surface shape of the recess 21 of the insulating substrate 2. The inner edge of the frame-shaped metal layer 6 may be shaped along the periphery of the through-hole 22 of the insulating substrate 2. The outer edge of the frame-shaped metal layer 6 may be shaped along the outer edge of the bottom surface of the recess 21 of the insulating substrate 2. As shown in FIG. 8, the inner edge of the frame-shaped metal layer 6 coincides with the periphery of the through-hole 22 of the insulating substrate 2, and the outer edge of the frame-shaped metal layer 6 is slightly smaller than the outer edge of the bottom surface of the recess 21 of the insulating substrate 2, but it is not limited thereto. The inner edge of the frame-shaped metal layer 6 may be slightly larger than the through-hole 22 of the insulating substrate 2 and may be separated from the periphery of the through-hole 22 of the insulating substrate 2, or the outer edge of the frame-shaped metal layer 6 may extend to the outer edge of the bottom surface of the recess 21 of the insulating substrate 2 and reach the inner side surface of the recess 21 of the insulating substrate 2. The portion extending to the outer edge of the bottom surface of the recess 21 of the insulating substrate 2 may be a part rather than the entire circumference.

[0019] As shown in FIGS. 4, 5, and 6, the wiring board 1 includes a rectangular plate-shaped heat radiating member 7 for radiating heat from the electronic component 300. The heat radiating member 7 is positioned in the recess 21 of the insulating substrate 2 so as to block the through hole 22. The heat radiating member 7 is made of a material with high thermal conductivity such as, for example, copper, copper-tungsten (Cu-W), or aluminum (Al). The heat radiating member 7 is joined to the frame-shaped metal layer 6 by a brazing material B. Further, the heat radiating member 7 has a component mounting surface 7a for mounting the electronic component 300 on the side of the through hole 22 of the insulating substrate 2. The shape of the heat radiating member 7 is not limited to a rectangular plate shape and can be appropriately changed according to the shape of the electronic component 300 and the like.

[0020] As shown in FIG. 9, the heat radiating member 7 is electrically connected to the connection pad 430 of the mother board 400 via a solder S. The connection pad 430 of the mother board 400 may have a function as a ground that defines a reference potential. At this time, the heat radiating member 7 functions as a ground terminal in the wiring board 1. In the example shown in FIG. 9, the electronic component 300 may have a ground electrode on the lower surface and be electrically connected to the heat radiating member 7, which is a ground terminal, by a conductive bonding material.

[0021] As shown in FIGS. 4, 7, and 8, the frame-shaped metal layer 6 has a convex portion 61 protruding toward the heat radiating member 7, and the convex portion 61 may be annular so as to surround the through hole 22 of the insulating substrate 2. The convex portion 61 of the frame-shaped metal layer 6 is positioned so as to overlap the heat radiating member 7 over the entire circumference in a plan view. A part of the convex portion 61 of the frame-shaped metal layer 6 may protrude from the heat radiating member 7 in a plan view.

[0022] As shown in FIGS. 1 and 4, when the insulating substrate 2 is made of, for example, an aluminum oxide sintered body, the insulating substrate 2 is manufactured as follows. Appropriate organic binders, solvents, etc. are added to and mixed with raw material powders such as aluminum oxide and silicon oxide to produce a slurry. This slurry is formed into a sheet by a doctor blade method, a calendar roll method, etc. to produce a ceramic green sheet for the insulating layer. Then, appropriate punching is performed on the ceramic green sheet for the insulating layer to form holes such as the recess 21 and the through hole 22 of the insulating substrate 2, and a plurality of ceramic green sheets for the insulating layer are laminated to produce a laminate (formed body) for the insulating substrate. The insulating substrate 2 is produced by firing the laminate for the insulating substrate at a high temperature (about 1300 to 1600 °C).

[0023] Similar to the insulating substrate 2, the insulating frame 3 is produced by performing appropriate punching on the ceramic green sheet for the insulating layer, laminating a plurality of ceramic green sheets for the insulating layer to produce a laminate (formed body) for the insulating frame, and laminating it on the laminate for the insulating substrate. Then, the insulating frame 3 is produced simultaneously with the insulating substrate 2 by firing the laminate for the insulating frame at a high temperature together with the laminate for the insulating substrate.

[0024] When the first wiring conductor 4, the second wiring conductor 5, and the frame-shaped metal layer 6 are, for example, tungsten metallization layers, they can be formed as follows. The wiring layer of the first wiring conductor 4, the wiring layer of the second wiring conductor 5, and the frame-shaped metal layer 6 are formed by printing a metal paste prepared by mixing tungsten powder with an organic solvent and an organic binder at a predetermined position on a ceramic green sheet for an insulating layer by a method such as screen printing and then firing. The through conductors of the first wiring conductor 4 and the second wiring conductor 5 are formed by providing holes for through conductors at predetermined positions on the ceramic green sheet for the insulating layer and filling the holes for through conductors with the metal paste. The convex portion 61 of the frame-shaped metal layer 6 can be formed, for example, by printing the metal paste on top of the metal paste printed in the shape of the frame-shaped metal layer 6. The height of the convex portion 61 can be adjusted, for example, by the printing thickness of the metal paste or the number of times of overprinting. By setting the printing thickness per time to be, for example, 10 μm to 50 μm, the height of the convex portion 61 (the thickness difference between the convex portion 61 of the frame-shaped metal layer 6 and the other portions) may be 10 μm to 50 μm.

[0025] On the surfaces of the first wiring conductor 4, the second wiring conductor 5, the frame-shaped metal layer 6, and the heat dissipation member 7 that are exposed to the outside, a nickel plating layer / gold plating layer may be deposited as a metal plating layer by a plating method such as electrolytic plating or electroless plating. Thereby, corrosion of the first wiring conductor 4, the second wiring conductor 5, etc. can be effectively reduced. The metal plating layer is not limited to the nickel plating layer / gold plating layer, and may be other metal plating layers including a nickel plating layer / palladium plating layer / gold plating layer, etc.

[0026] As the brazing material B for joining the heat radiating member 7 to the frame-shaped metal layer 6, for example, silver-copper (Ag-Cu) solder can be used. The brazing of the heat radiating member 7 is performed with the second surface 2b of the insulating substrate 2 facing upward. For example, a frame-shaped solder preform is placed on the frame-shaped metal layer 6, and the heat radiating member 7 is placed thereon and heated to melt the solder preform, and then cooled, whereby the heat radiating member 7 is joined to the frame-shaped metal layer 6 with the brazing material B. Alternatively, a clad material in which the brazing material B is bonded to one surface (component mounting surface 7a) of the heat radiating member 7 may be used. The heat radiating member 7 to which the brazing material B is bonded (clad) is placed on the frame-shaped metal layer 6 with the brazing material B facing downward and heated to melt the brazing material B, and then cooled, whereby the heat radiating member 7 is joined to the frame-shaped metal layer 6 with the brazing material B. When the clad material is used, in the process of joining the heat radiating member 7 to the frame-shaped metal layer 6, the process of aligning and arranging the brazing material B is omitted, so the productivity of the wiring board 1 is increased. When the solder preform is used, the possibility that the flatness of the component mounting surface 7a of the heat radiating member 7 is reduced by the brazing material B is smaller. In any method, the molten brazing material B spreads and wets on the frame-shaped metal layer 6 and is joined. By depositing the above metal plating layer on the surface of the frame-shaped metal layer 6, the molten brazing material B becomes more likely to spread and wet on the frame-shaped metal layer 6.

[0027] As shown in FIGS. 1, 2, and 4, the electronic device 200 includes a wiring board 1 and electronic components 300 mounted on the wiring board 1. The electronic components 300 are, for example, light-emitting elements such as LEDs (Light Emitting Diodes) and VCSEL (Vertical Cavity Surface Emitting Laser) type laser diodes, light-receiving elements such as photodiodes, semiconductor elements such as IC chips, and the like. The electronic components 300 are mounted on the component mounting surface 7a of the heat dissipation member 7 and are located within the through holes 22 of the insulating substrate 2. The electronic components 300 may protrude with respect to the first surface 2a of the insulating substrate 2. Further, after brazing the heat dissipation member 7 to the frame-shaped metal layer 6, the electronic components 300 are joined to the component mounting surface 7a of the heat dissipation member 7 by a joining material such as a resin adhesive, a conductive adhesive, or a low melting point brazing material. The first electrode of the electronic component 300 is electrically connected to the first electrode 41 of the first wiring conductor 4 by, for example, a bonding wire W. The second electrode of the electronic component 300 is electrically connected to the second electrode 51 of the second wiring conductor 5 by, for example, a bonding wire W.

[0028] As shown in FIGS. 1, 2, and 4, the electronic device 200 includes a lid 8 that closes the opening of the through hole 31 of the insulating frame 3, and the lid 8 is joined to the stepped portion 32 of the through hole 31 of the insulating frame 3 by a joining material such as a resin adhesive. When the electronic component 300 is an optical element such as a light-emitting element or a light-receiving element, the lid 8 is made of a light-transmissive material such as glass or resin. Also, at this time, as shown in FIGS. 1, 2, and 4, the lid 8 has a lens shape and may have a function as a lens, or may simply be a flat plate having a function as a light-transmissive member. When the electronic component 300 is a semiconductor element other than an optical element, the lid 8 may be a flat plate made of metal or ceramics.

[0029] Further, when the insulating frame 3 has the stepped portion 32, the lid 8 is easy to position, and since it is joined up to the side surface of the lid 8, the joining strength of the lid 8 is increased. Also, since the thickness increases by the thickness of the upper insulating layer, the strength of the wiring board 1 is also increased.

[0030] When the wiring board 1 has the insulating frame 3, a low-cost flat lid can be used, and even with a flat lid, a space for accommodating the electronic component 300 and the bonding wire W can be formed.

[0031] According to the configuration of the wiring board 1 according to Embodiment 1, as described above, the frame-shaped metal layer 6 has the convex portion 61 protruding toward the heat dissipation member 7, and the convex portion 61 of the frame-shaped metal layer 6 is positioned so as to overlap the heat dissipation member 7 in a plan view. Therefore, a space for holding the brazing material B is formed between the heat dissipation member 7 and the frame-shaped metal layer 6, and when brazing the heat dissipation member 7 to the frame-shaped metal layer 6, the outflow of the brazing material B to the component mounting surface 7a side of the heat dissipation member 7 can be reduced. Further, the convex portion 61 of the frame-shaped metal layer 6 can support the heat dissipation member 7, and when brazing the heat dissipation member 7 to the frame-shaped metal layer 6, the amount of the brazing material B extruded to the component mounting surface 7a side of the heat dissipation member 7 due to the self-weight of the heat dissipation member 7 can be reduced.

[0032] Therefore, according to the wiring board 1 according to Embodiment 1, it is possible to prevent the brazing material B from being located on the component mounting surface 7a of the heat dissipation member 7 or to reduce the amount of the brazing material B located on the component mounting surface 7a of the heat dissipation member 7. Therefore, according to the wiring board 1 according to Embodiment 1, the flatness of the component mounting surface 7a of the heat dissipation member 7 can be improved. As a result, the connection reliability between the wiring board 1 and the electronic component 300 can be enhanced, and at the same time, the heat dissipation performance can be improved.

[0033] Further, when the convex portion 61 of the frame-shaped metal layer 6 is annular and surrounds the through-hole 22 of the insulating substrate 2, and the brazing material B is preformed, when brazing the heat dissipation member 7 to the frame-shaped metal layer 6, the brazing material B located outside the convex portion 61 is blocked by the convex portion 61 of the frame-shaped metal layer 6. In order to further enhance the effect of blocking this brazing material, the inner dimension of the frame-shaped preform may be equal to or greater than the inner dimension of the annular convex portion 61. Also, as in the example shown in FIG. 8, the width of the portion of the frame-shaped metal layer 6 outside the convex portion 61 may be made larger than the width of the portion inside the convex portion 61. Further, the brazing material B located inside the convex portion 61 is held in the space between the frame-shaped metal layer 6 and the heat dissipation member 7. Thereby, the outflow of the brazing material B to the component mounting surface 7a side of the heat dissipation member 7 can be further reduced, and the flatness of the component mounting surface 7a of the heat dissipation member 7 is further improved.

[0034] When a clad material is used as the brazing material B, in order to form a larger space inside the annular convex portion 61, the annular convex portion 61 may have a shape that overlaps with the outer peripheral portion of the heat dissipation member 7 (with a larger inner dimension). The distance from the inner edge of the frame-shaped metal layer 6 to the inner edge of the convex portion 61 may be made larger than the distance from the outer edge of the frame-shaped metal layer 6 to the outer edge of the convex portion 61. In other words, the width of the portion of the frame-shaped metal layer 6 inside the convex portion 61 may be made larger than the width of the portion outside the convex portion 61. Thereby, a space for holding the brazing material B by the heat dissipation member 7 and the frame-shaped metal layer 6 can be enlarged inside the convex portion 61, and the brazing material B is likely to flow out to the outside from the component mounting surface 7a of the heat dissipation member 7.

[0035] The frame-shaped metal layer 6 may have a groove (a portion with a lower height) extending from the inside to the outside so that the brazing material B flows from the inside to the outside of the annular convex portion 61. When a plurality of grooves are provided at intervals in the circumferential direction, the brazing material B spreads to the outside over the entire circumference of the frame-shaped metal layer 6.

[0036] 〔Embodiment 2〕 Embodiment 2 will be described with reference to FIGS. 10 to 15. FIG. 10 is a schematic cross-sectional view of the electronic device according to Embodiment 2. FIG. 11 is a schematic bottom view of the electronic device shown in FIG. 10. FIG. 12 is a schematic perspective view of the wiring board according to Embodiment 2 as viewed from the second surface side of the insulating substrate, showing a state where the heat radiating member is removed. FIG. 13 is a schematic bottom view of the wiring board shown in FIG. 12, showing a state where the heat radiating member is removed. FIG. 14 is a schematic perspective view of another example of the wiring board according to Embodiment 2 as viewed from the second surface side of the insulating substrate, showing a state where a plurality of side surface metal layers are spaced apart in the circumferential direction on the inner peripheral surface of the recess of the insulating substrate. FIG. 15 is a schematic cross-sectional view showing a state where the electronic device shown in FIG. 10 is mounted on the mother board. FIG. 16 is a schematic partially enlarged cross-sectional view showing a state where the electronic device shown in FIG. 10 is mounted on the mother board.

[0037] As shown in FIGS. 10 and 11, the electronic device 200A according to Embodiment 2 includes the wiring board 1A according to Embodiment 2 and the electronic component 300 mounted on the wiring board 1. The wiring board 1A according to Embodiment 2 has the same configuration as the wiring board 1 according to Embodiment 1 except for some configurations. Among the configurations of the wiring board 1A according to Embodiment 2, the configurations different from those of the wiring board 1 according to Embodiment 1 will be described. For the sake of convenience of explanation, members having the same functions as the members described in Embodiment 1 are given the same reference numerals.

[0038] As shown in FIG. 10, the wiring board 1A according to Embodiment 2 may be configured in a flat plate shape without having the insulating frame 3 of Embodiment 1.

[0039] As shown in FIGS. 10, 12, and 13, the frame-shaped metal layer 6 as the frame-shaped metal part has a plurality of convex parts 61A protruding toward the heat dissipation member 7, and the plurality of convex parts 61A may be spaced apart in the circumferential direction of the frame-shaped metal layer 6. The plurality of convex parts 61A of the frame-shaped metal layer 6 are positioned so as to overlap the heat dissipation member 7 in a plan view. In the example shown in FIG. 13, the entire convex part 61A of the frame-shaped metal layer 6 is positioned so as to overlap the heat dissipation member 7 in a plan view. At least a part of each convex part 61A of the frame-shaped metal layer 6 may be positioned so as to overlap the heat dissipation member 7 in a plan view. In other words, a part of each convex part 61A of the frame-shaped metal layer 6 may protrude from the heat dissipation member 7 in a plan view. In addition to the convex parts 61A, the frame-shaped metal layer 6 may have one or a plurality of second convex parts (not shown) that do not overlap the heat dissipation member 7 in a plan view. The convex part 61A of the second embodiment can also be said to have a shape obtained by dividing the annular convex part 61 of the first embodiment. L-shaped convex parts 61A are respectively positioned near the four corners of the rectangular through hole 22, and linear convex parts 61A are respectively positioned near the four side parts of the rectangle. Thus, the plurality of convex parts 61A do not all have to be the same shape and the same size. Also, the convex parts 61A may be positioned only near the four corners of the through hole 22 as shown in FIG. 14, for example, or may be positioned only near the four side parts. The number and arrangement of the convex parts 61A may be set so that the heat dissipation member 7 can be supported without tilting when the heat dissipation member 7 is brazed to the frame-shaped metal layer 6.

[0040] As shown in FIGS. 10, 12, and 13, the wiring board 1A may include a side metal layer 9 as a side metal part positioned on the inner peripheral surface of the recess 21 of the insulating substrate 2. The side metal layer 9 is made of the same metal powder metallization as the first wiring conductor 4, the second wiring conductor 5, etc. The side metal layer 9 may be annular and extend over the entire circumference of the inner peripheral surface of the recess 21 of the insulating substrate 2. The side metal layer 9 is connected to the frame-shaped metal layer 6 and may extend from the bottom side to the opening side of the recess 21 of the insulating substrate 2. The side metal layer 9 may extend to the opening end of the recess 21 of the insulating substrate 2. The brazing material B for joining the heat dissipation member 7 is positioned from the frame-shaped metal layer 6 to the side metal layer 9.

[0041] As shown in FIG. 14, the number of the side metal layers 9 as the side metal parts is plural, and the plurality of side metal layers 9 may be spaced apart in the circumferential direction on the inner circumferential surface of the recess 21 of the insulating substrate 2. The side metal layer 9 can be formed as a metallized layer by printing a metal paste on the inner surface of the through hole of the ceramic green sheet that becomes the recess 21 and firing it.

[0042] As shown in FIGS. 10, 15, and 16, a space V may exist between the outer peripheral surface of the heat radiating member 7 and the side metal layer 9 on the opening side of the recess 21 of the insulating substrate 2. Even when the solder S climbs up to the side metal layer 9 when the wiring substrate 1A is soldered to the mother substrate 400, a space V may exist between the outer peripheral surface of the heat radiating member 7 and the side metal layer 9 on the opening side of the recess 21 of the insulating substrate 2.

[0043] As shown in FIG. 10, the first connection wiring 43 of the first wiring conductor 4 may have two through conductors, that is, a through conductor penetrating the upper insulating layer and a through conductor penetrating the lower insulating layer. At this time, the two through conductors are connected by a first connection wiring layer 44 located between the upper and lower insulating layers. The first connection wiring layer 44 is a wiring layer of the first wiring conductor 4. Also, the second connection wiring 53 of the second wiring conductor 5 may also have two through conductors, that is, a through conductor penetrating the upper insulating layer and a through conductor penetrating the lower insulating layer. The two through conductors of the second wiring conductor 5 are connected by a second connection wiring layer 54 located between the upper and lower insulating layers. The second connection wiring layer 54 is a wiring layer of the second wiring conductor 5.

[0044] As shown in FIG. 10, a nickel plating layer / gold plating layer may be deposited as a metal plating layer on the surfaces of the first wiring conductor 4, the second wiring conductor 5, the frame-shaped metal layer 6, the heat radiating member 7, and the side metal layer 9 that are exposed to the outside by a plating method such as an electrolytic plating method or an electroless plating method. Thereby, corrosion of the first wiring conductor 4, the second wiring conductor 5, etc. can be effectively reduced.

[0045] Instead of including the insulating frame 3 and the lid body 8 (see FIG. 4), the electronic device 200A has the following configuration.

[0046] As shown in FIG. 10, the wiring board 1A of the electronic device 200A may include a metallized layer 10 located at the peripheral portion of the first surface 21 of the insulating substrate 2. The metallized layer 10 is made of the same metal powder metallization as the first wiring conductor 4, the second wiring conductor 5, etc. The metallized layer 10 is formed by the same method as the wiring layers of the first wiring conductor 4 and the second wiring conductor 5, etc. A metal frame body may be further provided on the metallized layer 10. When the metallized layer 10 and the metal frame body are provided, the lid body 8A can be easily joined by welding such as brazing or resistance welding.

[0047] When the wiring board 1A does not include the insulating frame body 3, the electronic device 200A may include a cap-shaped lid body 8A. The lid body 8A has a cap-shaped lid body main body 81A joined to the metallized layer 10. The lid body main body 81A is made of a metal with a small difference in thermal expansion coefficient from ceramics, such as an iron-nickel (Fe-Ni) alloy or an iron-nickel-cobalt (Fe-Ni-Co) alloy. The lid body main body 81A may be made of ceramics in addition to metal. When the lid body main body 81A is made of metal, the lid body main body 81A can be manufactured by pressing a metal plate. When the lid body main body 81A is made of ceramics, a laminated body of ceramic green sheets may be fired in the same manner as the insulating substrate 2, or a cap-shaped molded body formed by pressing ceramic powder may be fired.

[0048] When the electronic component 300 is an optical element, as in the example shown in FIG. 10, the lid body 8A may be composed of a cap-shaped lid body main body 81A having an opening and a window member 83A closing the opening of the lid body main body 81A. The lid body main body 81A may have an annular step portion 82A in a plan view for positioning and holding the window member 83 at the center thereof. When the lid body main body 81A does not have the step portion 82A, the opening of the lid body main body 81A may be closed from the outside or the inside. The window member 83A transmits light emitted or received by the optical element and is made of a light-transmissive material such as glass, for example. The window member 83A may be lens-shaped as in the example shown in FIG. 10 or may be flat. When the electronic component 300 is a semiconductor element other than an optical element, the window member 83A may be flat and made of metal or ceramics. The window member 83A is joined to the lid body main body 81A with a joining material made of, for example, resin, glass, or the like. In the figure, the lid body main body 81A has an opening, but when the electronic component 300 is not an optical element, it may be a cap shape without an opening.

[0049] According to the configuration of the wiring board 1A according to Embodiment 2, as described above, the frame-shaped metal layer 6 has a plurality of convex portions 61A protruding toward the heat dissipation member 7 side, and the plurality of convex portions 61A are positioned so as to overlap the heat dissipation member 7 in a plan view. Therefore, a space for holding the brazing material B is formed between the heat dissipation member 7 and the frame-shaped metal layer 6, and when brazing the heat dissipation member 7 to the frame-shaped metal layer 6, the outflow of the brazing material B to the component mounting surface 7a side of the heat dissipation member 7 can be reduced. Further, the convex portions 61 of the frame-shaped metal layer 6 can support the heat dissipation member 7, and when brazing the heat dissipation member 7 to the frame-shaped metal layer 6, the amount of the brazing material B extruded to the component mounting surface 7a side of the heat dissipation member 7 due to the self-weight of the heat dissipation member 7 can be reduced.

[0050] Therefore, according to the wiring board 1A according to Embodiment 2, the brazing material B does not locate on the component mounting surface 7a of the heat dissipation member 7, or the amount of the brazing material B located on the component mounting surface 7a of the heat dissipation member 7 can be reduced. Thus, according to the wiring board 1A according to Embodiment 2, the flatness of the component mounting surface 7a of the heat dissipation member 7 can be improved. Thereby, while enhancing the connection reliability between the wiring board 1A and the electronic component 300, the heat dissipation performance can be improved.

[0051] When a plurality of convex portions 61A of the frame-shaped metal layer 6 are spaced apart in the circumferential direction of the frame-shaped metal layer 6, the space for holding the brazing material B between the heat dissipation member 7 and the frame-shaped metal layer 6 becomes larger compared to the case where the convex portion 61 is annular. Thereby, when brazing the heat dissipation member 7 to the frame-shaped metal layer 6, the outflow of the brazing material B to the component mounting surface 7a side of the heat dissipation member 7 can be further reduced. In particular, when the brazing material B is clad, a flow path for the brazing material B can be formed between the convex portions 61A adjacent in the circumferential direction, and when brazing the heat dissipation member 7 to the frame-shaped metal layer 6, the brazing material B easily flows out from the central portion (component mounting surface 7a) of the heat dissipation member 7 to the outer edge side of the frame-shaped metal layer 6 through this flow path. Thus, according to the wiring board 1A according to Embodiment 2, the flatness of the component mounting surface 7a of the heat dissipation member 7 can be further improved.

[0052] Even if the portion inside the convex portion 61A of the frame-shaped metal layer 6 (the portion outside the through hole 22 of the heat dissipation member 7) is not enlarged, the brazing material B can be made to flow out from the central portion to the outside of the heat dissipation member 7, so the wiring board 1A does not become larger.

[0053] Also, when a plurality of convex portions 61A of the frame-shaped metal layer 6 are spaced apart in the circumferential direction of the frame-shaped metal layer 6, the holding amount of the brazing material B between the heat dissipation member 7 and the frame-shaped metal layer 6 can be increased. Thereby, according to the wiring board 1A according to Embodiment 2, the bonding strength between the heat dissipation member 7 and the frame-shaped metal layer 6 is improved, and the stress on the insulating substrate 2 due to the difference in thermal expansion between the heat dissipation member 7 and the insulating substrate 2 is alleviated.

[0054] When the side metal layer 9 is located on the inner peripheral surface of the recess 21 of the insulating substrate 2, the brazing material B spreads wet up to the side metal layer 9 connected to the frame-shaped metal layer 6. As a result, when brazing the heat radiating member 7 to the frame-shaped metal layer 6, the outflow of the brazing material B to the component mounting surface 7a side of the heat radiating member 7 can be further reduced, or the outflow of the brazing material B from the component mounting surface 7a of the heat radiating member 7 to the outside can be further increased. Therefore, according to the wiring board 1A according to the second embodiment, the flatness of the component mounting surface 7a of the heat radiating member 7 can be further improved.

[0055] Also, when the side metal layer 9 is located on the inner peripheral surface of the recess 21 of the insulating substrate 2, even if the layer width of the frame-shaped metal layer 6 (the protruding length of the frame-shaped metal layer 6 with respect to the inner peripheral surface of the recess 21 of the insulating substrate 2) is shortened, the holding amount of the brazing material B can be increased. Further, thereby, according to the wiring board 1A according to the second embodiment, the recess 21 of the insulating substrate 2 can be made smaller.

[0056] When the side metal layer 9 is annular and extends over the entire circumference of the inner peripheral surface of the recess 21 of the insulating substrate 2, when brazing the heat radiating member 7 to the frame-shaped metal layer 6, the amount of the brazing material B flowing to the side metal layer 9 side increases, and the holding amount of the brazing material B between the heat radiating member 7 and the recess 21 of the insulating substrate 2 can be increased. Thereby, according to the wiring board 1A according to the second embodiment, the bonding strength between the heat radiating member 7 and the frame-shaped metal layer 6 is further improved, and the stress of the insulating substrate 2 due to the thermal expansion difference between the heat radiating member 7 and the insulating substrate 2 is further relaxed.

[0057] When a plurality of side metal layers 9 are spaced apart in the circumferential direction on the inner peripheral surface of the recess 21 of the insulating substrate 2, regions without the brazing material B exist at intervals in the circumferential direction between the outer peripheral surface of the heat radiating member 7 and the inner peripheral surface of the recess 21 of the insulating substrate 2. As a result, the stress of the insulating substrate 2 due to the thermal expansion difference between the heat radiating member 7 and the insulating substrate 2 is relaxed, and the heat dissipation performance from the brazing material B around the heat radiating member 7 is improved.

[0058] When the side metal layer 9 extends to the open end of the recess 21 of the insulating substrate 2, compared with the case where the side metal layer 9 reaches the middle of the depth of the recess 21 of the insulating substrate 2, even if the side metal layer 9 is annular, or a plurality of side metal layers 9 are spaced apart in the circumferential direction, the area of the side metal layer 9 and the brazing material B flowing through the side metal layer 9 increase, and the holding amount of the brazing material B can be increased. When the annular side metal layer 9 extends to the open end of the recess 21 of the insulating substrate 2, the holding amount of the brazing material B can be further increased.

[0059] When the side metal layer 9 extends to the open end of the recess 21 of the insulating substrate 2, as shown in FIGS. 15 and 16, when the wiring substrate 1A is soldered to the mother substrate 400, the solder S climbs up on the side metal layer 9, and a solder fillet Sf that spreads from the side metal layer 9 toward the center side of the recess 21 of the insulating substrate 2 is formed. Thereby, the solder S contacts the heat radiating member 7, and it becomes easier for the heat radiating member 7 to be joined to the connection pad 430 of the mother substrate 400.

[0060] Specifically, even if there is a variation in the position of the lower surface of the heat radiating member 7, it can be joined more reliably. In particular, when the lower surface of the heat radiating member 7 is located above (on the first surface 2a side) the lower surfaces of the external electrodes 42 and 52, when the electronic device 200A (wiring substrate 1A) is mounted on the mother substrate 400, the solder S on the connection pad 430 of the mother substrate 400 does not contact the heat radiating member 7, and there is a possibility that the heat radiating member 7 is not joined to the connection pad 430. By the side metal layer 9 extending to the open end of the recess 21 of the insulating substrate 2, the solder S contacts the side metal layer 9 and climbs up, and a solder fillet Sf is formed. The solder fillet Sf spreading from the side metal layer 9 toward the heat radiating member 7 contacts the heat radiating member 7, and further spreads wetly to the lower surface of the heat radiating member 7, so that the heat radiating member 7 is joined to the connection pad 430 of the mother substrate 400.

[0061] In order to more surely perform the joining by the solder fillet Sf, the distance from the lower surface of the external electrodes 42 and 52 to the lower surface of the heat dissipation member 7 may be 50 μm or less. Further, if the lower surface of the heat dissipation member 7 protrudes too far below the lower surfaces of the external electrodes 42 and 52, there is a possibility that the external electrodes 42 and 52 may have a poor connection, and thus the protrusion amount may be 100 μm or less.

[0062] The connection pads 430 of the mother substrate 400 may be larger than the through holes 22 (side surface metal layers 9) of the insulating substrate 2 in a plan view, and may be sized such that the outer edge is located outside the through holes 22 of the insulating substrate 2. The amount of solder S for forming the solder fillet Sf increases by the amount of solder S located outside the through holes 22 (side surface metal layers 9) of the insulating substrate 2. As a result, the solder S climbs up to the side surface metal layer 9, and the solder fillet Sf is easily formed. In other words, a larger solder fillet Sf that is easily connected by the heat dissipation member 7 is easily formed.

[0063] When a space V exists between the outer peripheral surface of the heat dissipation member 7 and the side surface metal layer 9 on the opening side of the recess 21 of the insulating substrate 2, as shown in FIGS. 15 and 16, when the wiring substrate 1A is solder-mounted on the mother substrate 400, the solder S climbs up to the side surface metal layer 9, and the solder fillet Sf is easily formed. Thereby, the solder S contacts the heat dissipation member 7, and the heat dissipation member 7 is easily joined by the connection pads 430 of the mother substrate 400. In order to more surely perform the joining by the solder fillet Sf, the width of the space V (the distance between the outer peripheral surface of the heat dissipation member 7 and the side surface metal layer 9) may be equal to or less than the thickness of the heat dissipation member 7.

[0064] 〔Embodiment 3〕 Embodiment 3 will be described with reference to FIGS. 17 to 23. FIG. 17 is a schematic cross-sectional view taken along line XVII-XVII in FIG. 19. FIG. 18 is a schematic cross-sectional view taken along line XVIII-XVIII in FIG. 19. FIG. 19 is a schematic bottom view of the electronic device according to Embodiment 3. FIG. 20 is a schematic perspective view of the wiring board according to Embodiment 3 as viewed from the second surface side of the insulating substrate, showing a state where the heat radiating member is removed. FIG. 21 is a schematic bottom view of the wiring board shown in FIG. 20, showing a state where the heat radiating member is removed. FIG. 22 is a schematic cross-sectional view showing a state where the electronic device shown in FIG. 19 is mounted on the mother board. FIG. 23 is a schematic partial enlarged cross-sectional view showing a state where the electronic device shown in FIG. 19 is mounted on the mother board.

[0065] As shown in FIGS. 17 to 19, the electronic device 200B according to Embodiment 3 includes the wiring board 1B according to the embodiment and the electronic components 300 mounted on the wiring board 1B. The wiring board 1B according to Embodiment 3 has the same configuration as the wiring board 1 according to Embodiment 1 except for some configurations. Among the configurations of the wiring board 1B according to Embodiment 3, the configurations different from those of the wiring board 1 according to Embodiment 1 will be described. For convenience of explanation, members having the same functions as the members described in Embodiment 1 are denoted by the same reference numerals.

[0066] The insulating frame 3 is composed of a single layer of insulating layer, and the through hole 31 of the insulating frame 3 does not have a stepped portion 32 (see FIG. 4). The wiring board 1B may include a metallized layer 10 located at the peripheral edge of the first surface 2a of the insulating substrate 2, and the metallized layer 10 is made of the same metal powder metallization as the first wiring conductor 4, the second wiring conductor 5, etc. The metallized layer 10 is formed by the same method as the wiring layers of the first wiring conductor 4 and the second wiring conductor 5, etc. The wiring board 1B may further include a metal frame 11 on the metallized layer 10. The metal frame 11 is made of a metal having a small difference in thermal expansion coefficient from ceramics, such as an iron-nickel (Fe-Ni) alloy or an iron-nickel-cobalt (Fe-Ni-Co) alloy. The metal frame 11 is joined to the metallized layer 10 by, for example, a brazing material.

[0067] As shown in FIGS. 17, 18, 20, and 21, the frame-shaped metal layer 6 as the frame-shaped metal part has a plurality of convex parts 61B protruding toward the heat radiating member 7 side, and the plurality of convex parts 61B may be spaced apart in the circumferential direction of the frame-shaped metal layer 6. The plurality of convex parts 61 of the frame-shaped metal layer 6 are positioned so as to overlap the heat radiating member 7 in a plan view. At least a part of each convex part 61B of the frame-shaped metal layer 6 is positioned so as to overlap the heat radiating member 7 in a plan view. In other words, a part of each convex part 61B of the frame-shaped metal layer 6 may protrude from the heat radiating member 7 in a plan view. The number and arrangement of the convex parts 61B may be the same as the number and arrangement of the convex parts 61A in Embodiment 2. The convex parts 61B may be circular in a plan view and smaller than the convex parts 61A in Embodiment 2. In this case, the space for holding the brazing material B is larger, and the flow path from the component mounting surface 7a of the heat radiating member 7 to the outside is larger. Since the convex parts 61B are circular in a plan view, it is difficult to prevent the flow of the brazing material B from the component mounting surface 7a of the heat radiating member 7 to the outside, and the brazing material B easily wraps around the outside of the convex parts 61B.

[0068] In addition to the convex parts 61B, the frame-shaped metal layer 6 may have one or a plurality of second convex parts (not shown) lower than the convex parts 61B. The second convex parts of the frame-shaped metal layer 6 may not overlap the heat radiating member 7 in a plan view.

[0069] As shown in FIGS. 17, 19, 20, and 21, the wiring board 1B may include a plurality of side surface metal bodies 9B as side surface metal portions located on the inner peripheral surface of the recess 21 of the insulating substrate 2. The brazing material B for joining the heat dissipation member 7 is located from the frame-shaped metal layer 6 to the side surface metal layer 9. The side surface metal body 9B is made of the same metal powder metallization as the first wiring conductor 4, the second wiring conductor 5, and the like. The side surface metal body 9B may be located in a plurality of grooves 23 provided at intervals in the circumferential direction on the inner peripheral surface of the recess 21 of the insulating substrate 2. In other words, the plurality of side surface metal bodies 9B may be located at intervals in the circumferential direction on the inner peripheral surface of the recess 21 of the insulating substrate 2. The plurality of side surface metal bodies 9B may be made of metallization filled in the plurality of grooves 23 of the insulating substrate 2. The side surface metal body 9B is made of the same metal powder metallization as the first wiring conductor 4, the second wiring conductor 5, and the like. The side surface metal body 9B is connected to the frame-shaped metal layer 6 and may extend from the bottom surface side to the opening side of the recess 21 of the insulating substrate 2. The side surface metal body 9B may extend to the opening end of the recess 21 of the insulating substrate 2.

[0070] As shown in FIGS. 17, 18, 22, and 23, a space V exists between the outer peripheral surface of the heat dissipation member 7 and the side surface metal body 9B on the opening side of the recess 21 of the insulating substrate 2. When the wiring board 1B is soldered and mounted on the mother board 400, even when the solder S climbs up the side surface metal body 9B, a space V exists between the outer peripheral surface of the heat dissipation member 7 and the side surface metal body 9B on the opening side of the recess 21 of the insulating substrate 2.

[0071] Although illustration is omitted, the wiring board 1B may be a side metal layer (side metallization layer) located along the inner surface of the groove 23 of the insulating substrate 2 instead of the side metal body 9B in which the groove 23 is filled with metallization as a side metal body. When the side metal body 9B or the side metal layer is located in a plurality of grooves 23 of the insulating substrate 2, compared with the case where a plurality of side metal layers 9 are provided on the inner side surface of the recess 21 of the insulating substrate 2 without the groove 23 as shown in the example of FIG. 14, the bonding strength between the side metal body 9B or the side metal layer and the insulating substrate 2 is improved. Further, when a plurality of grooves 23 of the insulating substrate 2 are filled with the side metal body 9B, since the cross-sectional area of the metal metallization is large, the heat transmitted to the side metal body 9B is easily transmitted to the lower surface (easily radiated). When the side metal layer is located along the inner surfaces of a plurality of grooves 23 of the insulating substrate 2, since the brazing material B enters the grooves 23 of the insulating substrate 2, the space for holding the brazing material B increases.

[0072] As shown in FIGS. 17 to 21, the wiring board 1B may include a second frame-shaped metal layer 12 as a second frame-shaped metal part located on the second surface 2b of the insulating substrate 2. The second frame-shaped metal layer 12 is made of the same metal powder metallization as the first wiring conductor 4, the second wiring conductor 5, and the like. The second frame-shaped metal layer 12 surrounds the opening of the recess 21 of the insulating substrate 2 and is connected to a plurality of side metal bodies 9B.

[0073] The grooves 23 of the insulating substrate 2 are formed by performing appropriate punching on the ceramic green sheet for the insulating layer, such as the recess 21 and the through hole 22 of the insulating substrate 2. When the side metal body 9B is, for example, a tungsten metallization layer, the side metal body 9B is formed by filling a hole corresponding to the groove 23 formed at a predetermined position of the ceramic green sheet for the insulating layer with a metal paste. When the wiring board 1B includes a side metal layer of the side metal body 9B as a side metal body, the side metal layer is formed by hole printing. The second frame-shaped metal layer 12 is formed by a thin film forming method such as a vapor deposition method, an ion plating method, or a sputtering method.

[0074] On the surfaces of the first wiring conductor 4, the second wiring conductor 5, the frame-shaped metal layer 6, the heat dissipation member 7, the side surface metal layer 9, the metallized layer 10, and the second frame-shaped metal layer 12 that are exposed to the outside, a nickel plating layer / gold plating layer may be deposited as a metal plating layer by a plating method such as an electrolytic plating method or an electroless plating method. Thereby, corrosion of the first wiring conductor 4, the second wiring conductor 5, etc. can be effectively reduced.

[0075] Instead of including the lid 8 (see FIG. 4), the electronic device 200B has the following configuration.

[0076] The electronic device 200B may include a flat lid 8B. The lid 8B may have a flat frame-shaped lid body 81B joined to the metal frame 11. The lid body 81B is made of a metal having a small difference in thermal expansion coefficient from ceramics, such as an iron-nickel (Fe-Ni) alloy or an iron-nickel-cobalt (Fe-Ni-Co) alloy. The lid 8B may be joined to the metal frame 11 by resistance welding such as brazing or seam welding.

[0077] When the electronic component 300 is an optical element, as in the example shown in FIG. 17, the lid 8B may be composed of a flat frame-shaped lid body 81B having an opening and a window member 82B closing the opening of the lid body 81B. In FIG. 17, the window member 82B closes the opening of the lid body 81B from the inside, but it may also close the opening from the outside. The window member 82B transmits light emitted or received by the optical element and is made of a light-transmitting material such as glass. The window member 82B may be lens-shaped as in the example shown in FIG. 17 or flat. When the electronic component 300 is a semiconductor element other than an optical element, the lid body 81B may be flat and made of metal or ceramics and have no opening. When the lid body 81B is made of ceramics, a metal film for bonding may be provided on the ceramics and joined to the metal frame 11 by brazing, or it may be joined with a bonding material such as resin or glass without providing a metal film. When using a bonding material such as resin or glass, the wiring board 1B may not include the metallized layer 10 and the metal frame 11.

[0078] According to the configuration of the wiring board 1B according to Embodiment 3, as described above, the frame-shaped metal layer 6 has a plurality of convex portions 61B protruding toward the heat radiating member 7 side, and the plurality of convex portions 61B are positioned so as to overlap the heat radiating member 7 in a plan view. Therefore, a space for holding the brazing material B is formed between the heat radiating member 7 and the frame-shaped metal layer 6, and when brazing the heat radiating member 7 to the frame-shaped metal layer 6, the outflow of the brazing material B to the component mounting surface 7a side of the heat radiating member 7 can be reduced. Further, the convex portion 61 of the frame-shaped metal layer 6 can support the heat radiating member 7, and when brazing the heat radiating member 7 to the frame-shaped metal layer 6, the amount of the brazing material B extruded to the component mounting surface 7a side of the heat radiating member 7 due to the self-weight of the heat radiating member 7 can be reduced.

[0079] Therefore, according to the wiring board 1B according to Embodiment 3, it is possible to prevent the brazing material B from being located on the component mounting surface 7a of the heat radiating member 7 or to reduce the amount of the brazing material B located on the component mounting surface 7a of the heat radiating member 7. Therefore, according to the wiring board 1B according to Embodiment 3, the flatness of the component mounting surface 7a of the heat radiating member 7 can be improved. As a result, the connection reliability between the wiring board 1B and the electronic component 300 can be enhanced, and at the same time, the heat dissipation performance can be improved.

[0080] When the plurality of convex portions 61B of the frame-shaped metal layer 6 are spaced apart in the circumferential direction of the frame-shaped metal layer 6, the space for holding the brazing material B between the heat radiating member 7 and the frame-shaped metal layer 6 becomes larger than when the convex portion 61 is annular. Thereby, when brazing the heat radiating member 7 to the frame-shaped metal layer 6, the outflow of the brazing material B to the component mounting surface 7a side of the heat radiating member 7 can be further reduced. In particular, when the brazing material B is clad, a flow path for the brazing material B can be formed between the convex portions 61B adjacent in the circumferential direction, and when brazing the heat radiating member 7 to the frame-shaped metal layer 6, the brazing material B easily flows out from the central portion (component mounting surface 7a) of the heat radiating member through this flow path to the outer edge side of the frame-shaped metal layer 6. Therefore, according to the wiring board 1B according to Embodiment 3, similar to the wiring board 1A according to Embodiment 2, the flatness of the component mounting surface 7a of the heat radiating member 7 can be further improved.

[0081] Even if the portion inside the convex portion 61B of the frame-shaped metal layer 6 (the portion outside the through-hole 22 of the heat dissipation member 7) is not enlarged, the brazing material B can flow out from the central portion of the heat dissipation member 7 to the outside, so that the wiring board 1B does not become large.

[0082] When the plurality of convex portions 61B of the frame-shaped metal layer 6 are spaced apart in the circumferential direction of the frame-shaped metal layer 6, the holding amount of the brazing material B between the heat dissipation member 7 and the frame-shaped metal layer 6 can be increased. Thereby, according to the wiring board 1B according to Embodiment 3, the bonding strength between the heat dissipation member 7 and the frame-shaped metal layer 6 is improved, and the stress of the insulating substrate 2 due to the difference in thermal expansion between the heat dissipation member 7 and the insulating substrate 2 is relaxed.

[0083] When the plurality of side surface metal bodies 9B are located on the inner peripheral surface of the concave portion 21 of the insulating substrate 2, the brazing material B spreads wet to the side surface metal body 9B connected to the frame-shaped metal layer 6. Thereby, when brazing the heat dissipation member 7 to the frame-shaped metal layer 6, the outflow of the brazing material B to the component mounting surface 7a side of the heat dissipation member 7 can be further reduced. Therefore, according to the wiring board 1B according to Embodiment 3, the flatness of the component mounting surface 7a of the heat dissipation member 7 can be further improved.

[0084] Further, when the side surface metal body 9B is located on the inner peripheral surface of the concave portion 21 of the insulating substrate 2, even if the layer width of the frame-shaped metal layer 6 is shortened, the holding amount of the brazing material B can be increased. Thereby, according to the wiring board 1B according to Embodiment 3, the concave portion 21 of the insulating substrate 2 can be made smaller, and the wiring board 1B can be miniaturized, in other words, the electronic device 200B can be miniaturized.

[0085] When the plurality of side surface metal bodies 9B are spaced apart in the circumferential direction of the inner peripheral surface of the concave portion 21 of the insulating substrate 2, a region without the brazing material B exists between the outer peripheral surface of the heat dissipation member 7 and the inner peripheral surface of the concave portion 21 of the insulating substrate 2 at intervals in the circumferential direction. Thereby, the stress of the insulating substrate 2 due to the difference in thermal expansion between the heat dissipation member 7 and the insulating substrate 2 is relaxed, and the heat dissipation property from the brazing material B around the heat dissipation member 7 is improved.

[0086] When the side metal layer 9 extends to the opening end of the recess 21 of the insulating substrate 2, as shown in FIGS. 22 and 23, when the wiring substrate 1B is soldered to the mother substrate 400, the solder S climbs up the side metal body 9B, and a solder fillet Sf that spreads from the side metal body 9B toward the center side of the recess 21 of the insulating substrate 2 is formed. As a result, the solder S contacts the heat dissipation member 7, and the heat dissipation member 7 is easily joined to the connection pad 430 of the mother substrate 400.

[0087] When a space V exists between the outer peripheral surface of the heat dissipation member 7 and the side metal body 9B on the opening side of the recess 21 of the insulating substrate 2, it is shown in FIGS. 22 and 23. When the wiring substrate 1B is soldered to the mother substrate 400, the solder S climbs up the side metal body 9B, and the solder fillet Sf is easily formed. As a result, the solder S contacts the heat dissipation member 7, and the heat dissipation member 7 is easily joined by the connection pad 430 of the mother substrate 400. In order to make the joining by the solder fillet Sf more reliable, the width of the space V (the distance between the outer peripheral surface of the heat dissipation member 7 and the side metal body 9B) may be equal to or less than the thickness of the heat dissipation member 7.

[0088] When the second frame-shaped metal layer 12 is located on the second surface 2b of the insulating substrate 2, as shown in FIGS. 21 and 22, when the wiring substrate 1B is soldered to the mother substrate 400, the solder S easily climbs up the side metal body 9B, and the solder fillet Sf is easily formed. As a result, the solder S contacts the heat dissipation member 7, and the heat dissipation member 7 is easily joined by the connection pad 430 of the mother substrate 400.

[0089] Specifically, the second frame-shaped metal layer 12 is located on the second surface 2b of the insulating substrate 2 at the same height position as the external electrodes 42, 52. Therefore, when the external electrodes 42, 52 contact the solder S, the second frame-shaped metal layer 12 also contacts the solder S. Since the second frame-shaped metal layer 12 is connected to the side metal body 9B, the solder S wets and spreads from the second frame-shaped metal layer 12 to the side metal body 9B, and the solder fillet Sf is formed more reliably.

[0090] The connection pad 430 may be positioned such that its outer edge is located outside the outer edge of the second frame-shaped metal layer 12. The amount of solder S for forming the solder fillet Sf increases by the difference in size between the connection pad 430 and the second frame-shaped metal layer 12. As a result, the solder S climbs up the side metal body 9B, and the solder fillet Sf is more likely to be formed. In other words, a larger solder fillet Sf that is easier to connect by the heat dissipation member 7 is more likely to be formed.

[0091] 〔Other Embodiments〕 Although not shown, the inner peripheral surface of the recess 21 of the insulating substrate 2 may be inclined with respect to the thickness direction of the insulating substrate 2 so as to gradually move away from the outer peripheral surface of the heat dissipation member 7 toward the opening end side of the recess 21. In this case, the plating solution easily enters the recess 21 of the insulating substrate 2, and the occurrence of plating defects such as plating chipping can be reduced.

[0092] The heat dissipation member 7 may have a plurality of protrusions that contact the inner peripheral surface of the recess 21 of the insulating substrate 2 on its outer peripheral surface. Alternatively, the insulating substrate 2 may have protrusions that contact the outer peripheral surface of the heat dissipation member 7 on the inner peripheral surface of the recess 21. In this case, it becomes easier to position the heat dissipation member 7 in the recess 21 of the insulating substrate 2.

[0093] The distance between the inner peripheral surface of the recess 21 of the insulating substrate 2 and the outer peripheral surface of the heat dissipation member 7 is not constant in the circumferential direction, and may locally have an area where the distance between the inner peripheral surface of the recess 21 of the insulating substrate 2 and the outer peripheral surface of the heat dissipation member 7 is wide. By making the bottom view shape of the heat dissipation member 7 circular, an area where the distance between the inner peripheral surface of the recess 21 of the insulating substrate 2 and the outer peripheral surface of the heat dissipation member 7 is wide may be locally formed. In this case, when the plating solution enters the wide area, it easily enters the entire circumference of the outer peripheral surface of the heat dissipation member 7 due to capillary action.

[0094] Another electronic component such as a diode, a coil, or a capacitor may be mounted on the first surface 2a of the insulating substrate 2. The other electronic components also include electronic components for controlling the electronic component 300.

[0095] The invention according to the present disclosure has been described above based on the drawings and examples. However, the invention according to the present disclosure is not limited to each of the above-described embodiments. That is, the invention according to the present disclosure can be variously modified within the scope shown in the present disclosure, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the invention according to the present disclosure. In other words, it should be noted that those skilled in the art can easily make various deformations or modifications based on the present disclosure. Also, it should be noted that these deformations or modifications are included in the scope of the present disclosure.

Explanation of Reference Numerals

[0096] 1 Wiring board (wiring board according to Embodiment 1) 2 Insulating substrate 2a First surface 2b Second surface 21 Recess of insulating substrate 22 Through-hole of insulating substrate 3 Insulating frame 31 Through-hole of insulating frame 32 Step portion of through-hole of insulating frame 4 First wiring conductor 41 First electrode 42 First external electrode 43 First connection wiring 5 Second wiring conductor 51 Second electrode 52 Second external electrode 53 Second connection wiring 6 Frame-shaped metal layer (frame-shaped metal part) 61 Protrusion 7 Heat dissipation member 7a Component mounting surface 8 Cover 200 Electronic device (electronic device according to Embodiment 1) 300 Electronic component 400 Mother board 410 First electrode of mother board 420 Second electrode of mother board 430 Connection pad of mother board B Brazing material S Solder V space W bonding wire 1A wiring board (wiring board according to Embodiment 2) 44 First connection wiring layer 54 Second connection wiring layer 61A Protrusion 8A Cover 81A Cover body 82A Step portion 83A Window member 9 Side metal layer (side metal portion) 10 Metallization layer 11 Metal frame 200A Electronic device (electronic device according to Embodiment 2) Sf Solder fillet 1B wiring board (wiring board according to Embodiment 3) 23 Groove 61B Protrusion 8B Cover 81B Cover body 82B Window member 9B Side metal body (side metal portion) 12 Second frame-shaped metal layer (second frame-shaped metal body) 200B Electronic device (electronic device according to Embodiment 3)

Claims

1. an insulating substrate having a first surface, a second surface located opposite to the first surface, a recessed portion opening into the second surface, and a through hole extending from a bottom surface of the recessed portion to the first surface; A wiring conductor located from the first surface to the second surface; a frame-shaped metal portion located on a bottom surface of the recess and surrounding the through hole; a flat-plate-shaped heat dissipation member located in the recess so as to close the through hole, joined to the frame-shaped metal portion by a brazing material, and having a component mounting surface on the through hole side, The frame-shaped metal portion has a convex portion that protrudes toward the heat dissipation member, and the convex portion is positioned so as to overlap the heat dissipation member in a planar perspective view.

2. The wiring board according to claim 1 , wherein the protrusion is annular and surrounds the through hole.

3. The wiring board according to claim 1 , wherein the number of the protruding portions is more than one, and the protruding portions are positioned at intervals in the circumferential direction of the frame-shaped metal portion.

4. The wiring board according to claim 1 , further comprising a side metal portion located on an inner circumferential surface of the recess, connected to the frame-shaped metal portion, and extending from a bottom side of the recess to an opening side.

5. The wiring board according to claim 4 , wherein the side metal portion is annular and is positioned around the entire periphery of the inner periphery of the recess.

6. The wiring board according to claim 4 , wherein the number of the side metal portions is plural, and the side metal portions are positioned at intervals in the circumferential direction of the inner circumferential surface of the recess.

7. The number of the side metal portions is plural, the insulating substrate has a plurality of grooves provided at intervals in a circumferential direction on an inner circumferential surface of the recess, The wiring board according to claim 4 , wherein the side metal portions are located in the grooves, respectively.

8. The wiring board according to claim 4 , wherein the side metal portion extends to an opening end of the recess.

9. The wiring board according to claim 8 , further comprising a second frame-shaped metal portion located on the second surface, connected to the side metal portion, and surrounding an opening of the recess.

10. The wiring board according to claim 4 , wherein a space exists between an outer peripheral surface of the heat dissipation member and the side metal portion on an opening side of the recess.

11. The wiring board according to claim 1 , an electronic component mounted on the component mounting surface of the heat dissipation member, positioned within the through hole, and electrically connected to the wiring conductor.

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