Wiring board and semiconductor device

Abstract

A wiring board according to the present disclosure comprises a first insulating substrate, a second insulating substrate, a first electrode, and a second electrode. The first insulating substrate contains a ceramic material. The second insulating substrate contains a resin material and is bonded to the first insulating substrate. The first electrode is located on a surface of the first insulating substrate other than the bonding area with the second insulating substrate, and has a plurality of first metal layers. The second electrode is located on a surface of the second insulating substrate other than the bonding area with the first insulating substrate, is electrically connected to the first electrode, and has a plurality of second metal layers. The number of first metal layers is equal to or greater than the number of second metal layers.

Description

Wiring board and semiconductor device

[0001] The disclosed embodiments relate to a wiring substrate and a semiconductor device.

[0002] 2. Description of the Related Art Conventionally, a composite wiring board in which a resin substrate portion and a ceramic substrate portion are joined together has been known (see Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2019-121720

[0004] The wiring board of the present disclosure includes a first insulating substrate, a second insulating substrate, a first electrode, and a second electrode. The first insulating substrate contains a ceramic material. The second insulating substrate contains a resin material and is bonded to the first insulating substrate. The first electrode is located on a surface of the first insulating substrate other than the bonding area with the second insulating substrate, and has a plurality of first metal layers. The second electrode is located on a surface of the second insulating substrate other than the bonding area with the first insulating substrate, and is electrically connected to the first electrode and has a plurality of second metal layers. The number of first metal layers is equal to or greater than the number of second metal layers.

[0005] FIG. 1 is a perspective view showing an example of the configuration of a wiring board according to an embodiment. FIG. 2 is a diagram showing an example of a cross-sectional perspective view of the wiring board cut along line A-A shown in FIG. 1. FIG. 3 is a cross-sectional view showing an example of the configuration of a first internal conductor, a second internal conductor, and an interlayer conductor. FIG. 4 is a diagram showing an example of a cross-sectional view of a portion of the wiring board cut along line B-B shown in FIG. 1. FIG. 5 is a cross-sectional view showing an example of the configuration of a first electrode and a second electrode according to the first embodiment. FIG. 6A is a cross-sectional view showing an example of the configuration of a first electrode and a second electrode according to the second embodiment. FIG. 6B is a cross-sectional view showing an example of the configuration of a first electrode and a second electrode according to the third embodiment. FIG. 6C is a cross-sectional view showing an example of the configuration of a first electrode and a second electrode according to the fourth embodiment. FIG. 6D is a cross-sectional view showing an example of the configuration of a first electrode and a second electrode according to the fifth embodiment. FIG. 7 is a perspective view showing an example of the configuration of a semiconductor device according to an embodiment. FIG. 8 is a cross-sectional perspective view showing another example of the configuration of a wiring board according to an embodiment. FIG. 9 is a cross-sectional view showing an example of the configuration of a first electrode and a second electrode according to the sixth embodiment.

[0006] Hereinafter, embodiments for carrying out a wiring board and a semiconductor device according to the present disclosure (hereinafter referred to as "embodiments") will be described in detail with reference to the drawings. Note that the present disclosure is not limited to these embodiments. Furthermore, the embodiments can be appropriately combined within the scope of not causing contradictions in content. Furthermore, the same components in the following embodiments will be assigned the same reference numerals, and duplicated explanations may be omitted.

[0007] In addition, in the drawings referred to below, to make the explanation easier to understand, an orthogonal coordinate system may be shown in which the X-axis direction, Y-axis direction, and Z-axis direction, which are perpendicular to each other, are defined, and the Z-axis direction is the thickness direction of the wiring board.

[0008] <Introduction> Composite wiring boards formed by bonding a resin substrate and a ceramic substrate are known, but this conventional technology leaves room for further improvement in terms of extending the life of wiring boards formed by bonding two insulating substrates. Specifically, electrodes are disposed on the surfaces of the resin substrate and the ceramic substrate, respectively, and the electrodes are electrically connected via wiring within the resin substrate and the ceramic substrate. Each electrode has multiple metal layers, and the greater the number of metal layers, the greater the number of interfaces between the metal layers, and the greater the electrical resistance. Therefore, the greater the number of metal layers in an electrode, the higher the electrical resistance and the greater the power consumption for a given current value. In other words, the greater the number of metal layers in an electrode, the more likely it is to generate heat.

[0009] The present disclosure provides a technology that can extend the life of a wiring substrate formed by bonding two insulating substrates. Resin substrates have lower thermal conductivity and are less likely to dissipate heat than ceramic substrates. Therefore, when the number of metal layers on the electrodes on the surface of the resin substrate is equal to or less than the number of metal layers on the electrodes on the surface of the ceramic substrate, heat generation in the electrodes of the resin substrate can be reduced compared to when the number of metal layers on the electrodes on the surface of the resin substrate is greater than the number of metal layers on the electrodes on the surface of the ceramic substrate. This reduces the possibility of the temperature of the resin substrate increasing due to heat generation in the electrodes. This can extend the life of, for example, the resin substrate, and ultimately the wiring substrate.

[0010] According to the present disclosure, it is possible to extend the life of a wiring board formed by bonding two insulating substrates. In the embodiment described below, an electrode structure that can extend the life of a wiring board formed by bonding two insulating substrates, i.e., a first insulating substrate 10, which is an example of a ceramic substrate, and a second insulating substrate 20, which is an example of a resin substrate, will be described.

[0011] 1 is a perspective view showing an example of the configuration of a wiring board according to an embodiment, and FIG. 2 is a cross-sectional perspective view of the wiring board taken along line AA shown in FIG.

[0012] 1 and 2, the wiring board 100 according to the embodiment has a first insulating substrate 10, a second insulating substrate 20, a first internal conductor 30, a second internal conductor 40, and an interlayer conductor 50. Furthermore, as shown in FIG. 2, the wiring board 100 according to the embodiment has a first electrode 110 and a second electrode 120.

[0013] In this disclosure, the planar view refers to a planar view seen in the thickness direction of the wiring substrate 100, i.e., a direction perpendicular to the horizontal direction of the wiring substrate 100, and is a concept that includes a planar perspective view in which some components are seen through from the Z direction. Furthermore, the horizontal direction in this disclosure refers to the XY plane direction.

[0014] The wiring substrate 100 is a laminate of a first insulating substrate 10 and a second insulating substrate 20. The wiring substrate 100 may be, for example, a polygonal shape, including a rectangular shape, in a plan view, and some or all of the outer edge may be curved. The wiring substrate 100 may also have a through hole 200 in a position offset toward the center or the outer edge in a plan view. The through hole 200 may be rectangular in a plan view. The portion of the through hole 200 that penetrates the second insulating substrate 20 may be larger horizontally than the portion that penetrates the first insulating substrate 10. Without being limited to the above, the portion of the through hole 200 that penetrates the second insulating substrate 20 may be horizontally smaller than or the same as the portion that penetrates the first insulating substrate 10. Furthermore, the first insulating substrate 10 and / or the second insulating substrate 20 may protrude inward from at least a portion of the inner wall surface of the through hole 200. The wiring substrate 100 may also be flat and have no through hole 200. In addition, in the wiring substrate 100, the second insulating substrate 20 may have a recess instead of the first insulating substrate 10 and / or the through hole 200.

[0015] (First Insulating Substrate) The first insulating substrate 10 may contain ceramic or may have ceramic as its main component. In the present disclosure, a main component refers to, for example, a material that accounts for 50% by mass or more of the material. Examples of ceramics that can be used include ceramics containing at least one selected from the group consisting of aluminum oxide, silicon oxide, zirconium oxide, silicon carbide, silicon nitride, and aluminum nitride as its main component, or ceramics containing a composite oxide such as mullite, zircon, steatite, enstatite, glass ceramics, and glass as its main component. The first insulating substrate 10 may contain a glass material in addition to ceramic. The first insulating substrate 10 may be an insulating substrate made of a glass substrate, and may contain a glass material like an insulating substrate containing ceramic as its main component.

[0016] As shown in Fig. 2, the first insulating substrate 10 has a first surface 11 and a second surface 12 located opposite the first surface 11. The first insulating substrate 10 may be a plate-like body having the first surface 11 and the second surface 12 as its main surfaces. The first insulating substrate 10 may also have a first side surface 13 connecting the first surface 11 and the second surface 12. The first side surface 13 is the outer surface of the first insulating substrate 10. The first side surface 13 is a surface that intersects with the first surface 11 and the second surface 12. The first side surface 13 may also be a surface that is perpendicular to the first surface 11 and the second surface 12.

[0017] The first insulating substrate 10 may have a plurality of ceramic layers 14. The plurality of ceramic layers 14 may be stacked along the thickness direction of the first insulating substrate 10. By configuring the first insulating substrate 10 using a plurality of ceramic layers 14, it is possible to obtain a first insulating substrate 10 having therein conductors with wiring shapes suitable for various purposes. Furthermore, by making the plurality of ceramic layers 14 different in shape and thickness, the degree of freedom in designing the shape of the wiring substrate 100 can be improved.

[0018] The number of ceramic layers 14 is not limited to three. The number of ceramic layers 14 may be two or more. Furthermore, the first insulating substrate 10 does not necessarily have to have a multi-layer structure. In other words, the first insulating substrate 10 may be a single layer.

[0019] (Second Insulating Substrate) The second insulating substrate 20 may contain a resin material. The resin material may be an organic resin. The organic resin may be, for example, an epoxy resin, an acrylic resin, a polycarbonate resin, a polyimide resin, an olefin resin, a maleimide resin, or a polyphenylene resin. The second insulating substrate 20 may also contain multiple types of resin materials. The organic resin may be, for example, polytetrafluoroethylene (PTFE) or other fluororesins or polyphenylene ether resin. The second insulating substrate 20 may also contain components other than the organic resin. Examples of components other than the resin material contained in the second insulating substrate 20 include inorganic materials such as silica and rubber materials. The content of inorganic materials such as silica in the second insulating substrate 20, in terms of mass percentage, may be greater than the content of resin materials in the second insulating substrate 20. More specifically, the content of inorganic materials such as silica in the second insulating substrate 20 may be 50% by mass or more of the second insulating substrate 20, and the content of resin materials in the second insulating substrate 20 may be 50% by mass or less of the second insulating substrate 20.

[0020] As shown in Fig. 2, the second insulating substrate 20 has a third surface 21 and a fourth surface 22 located opposite the third surface. The second insulating substrate 20 may be a plate-like body having the third surface 21 and the fourth surface 22 as its main surfaces. The second insulating substrate 20 may also have a second side surface 23 connecting the third surface 21 and the fourth surface 22. The second side surface 23 is an outer surface of the second insulating substrate 20. The second side surface 23 is a surface that intersects with the third surface 21 and the fourth surface 22. The second side surface 23 may also be a surface that is perpendicular to the third surface 21 and the fourth surface 22.

[0021] The second insulating substrate 20 is placed on the first surface 11 of the first insulating substrate 10, and the third surface 21 of the second insulating substrate 20 is bonded to the first surface 11 of the first insulating substrate 10. In other words, the second insulating substrate 20 is bonded directly to the first insulating substrate 10 without an adhesive layer therebetween. The adhesive layer referred to here refers to a layer containing, for example, an epoxy resin, a polyimide resin, a polyamideimide resin, or the like, and on which no conductors for wiring such as via conductors are explicitly formed.

[0022] The first insulating substrate 10 and the second insulating substrate 20 may be bonded together by, for example, hydrogen bonding. Specifically, the first insulating substrate 10 and the second insulating substrate 20 are bonded together by bonding between hydroxyl groups of the first insulating substrate 10 and the second insulating substrate 20. By directly bonding the first insulating substrate 10 and the second insulating substrate 20 in this manner without using solder, underfill, or the like, the thickness of the wiring substrate 100 can be reduced and the manufacturing process can be simplified.

[0023] The second insulating substrate 20 may have multiple resin layers 24. The multiple resin layers 24 may be stacked along the thickness direction of the second insulating substrate 20. By using multiple resin layers 24 to form the second insulating substrate 20, it is possible to obtain a second insulating substrate 20 having conductors with wiring shapes suitable for various purposes. Furthermore, by making the multiple resin layers 24 different shapes and thicknesses, the degree of freedom in designing the shape of the wiring substrate 100 can be improved. Note that the resin layer 24 refers to a layer containing a resin material, and includes not only a layer composed only of a resin material, but also a layer containing an inorganic material such as silica in the resin material. Furthermore, the content of the resin material in the resin layer 24 in terms of mass % may be smaller than the content of the inorganic material in the resin layer 24 in terms of mass %.

[0024] The number of resin layers 24 is not limited to two. The number of resin layers 24 may be three or more. Furthermore, the second insulating substrate 20 does not necessarily have to have a multi-layer structure.

[0025] Ceramics have higher rigidity than resins, so by combining the first insulating substrate 10 and the second insulating substrate 20, the wiring substrate 100 can achieve finer wiring and narrower pitches while also increasing its rigidity.

[0026] Furthermore, if the second insulating substrate 20 containing a resin material is lighter than the first insulating substrate 10 containing a ceramic, the wiring board 100 according to the present disclosure having the first insulating substrate 10 and the second insulating substrate 20 can be made lighter than a wiring board having only the first insulating substrate 10.

[0027] (First Electrode) The first electrode 110 is located on the surface of the first insulating substrate 10 other than the joint portion with the second insulating substrate 20. In the example shown in FIG. 2, the first electrode 110 is located on the second surface 12. The first electrode 110 has a plurality of first metal layers 130. The configuration of the plurality of first metal layers 130 will be described later with reference to FIGS. 4, 5, and 6A to 6D.

[0028] (Second Electrode) The second electrode 120 is located on the surface of the second insulating substrate 20 other than the joint with the first insulating substrate 10. In the example shown in Fig. 2, the second electrode 120 is located on the fourth surface 22. The second electrode 120 has a plurality of second metal layers 140. The configuration of the plurality of second metal layers 140 will be described later with reference to Figs. 4, 5, and 6A to 6D.

[0029] (First Internal Conductor, Second Internal Conductor, and Interlayer Conductor) The first internal conductor 30, the second internal conductor 40, and the interlayer conductor 50 are formed inside the first insulating substrate 10 and the second insulating substrate 20. FIG. 3 is a cross-sectional view showing an example of the configuration of the first internal conductor 30, the second internal conductor 40, and the interlayer conductor 50. As shown in FIGS. 2 and 3 , the first internal conductor 30 is located inside the first insulating substrate 10. The first internal conductor 30 extends in a direction perpendicular to the first surface 11. Note that "extending" here does not necessarily mean extending over the shortest distance. Furthermore, a portion of the first internal conductor 30 may reach the second surface 12 or the first side surface 13. A portion of the first internal conductor 30 may extend in a direction perpendicular to the second surface 12 and be electrically connected to the first electrode 110.

[0030] 3 , the first internal conductor 30 has a first via conductor 31 that penetrates at least a portion of the first insulating substrate 10, and a first land conductor 32 that is electrically connected to the first via conductor 31. The first via conductor 31 penetrates one or more ceramic layers 14. The first land conductor 32 may be located between the multiple ceramic layers 14. The first land conductor 32 may be a portion that is located around the first via conductor 31 in a planar view. In other words, the first land conductor 32 may be located at a position that overlaps with the first via conductor 31 in a planar view. Here, in the present disclosure, a via conductor refers to a portion that penetrates between layers in the thickness direction of the wiring substrate 100.

[0031] The first inner conductor 30 may be a metal conductor containing, for example, copper, tungsten, or molybdenum as its main component. The first via conductor 31 and the first land conductor 32 may be made of the same metal or different metals. For example, the first via conductor 31 and the first land conductor 32 may both be metal conductors containing tungsten as their main component or molybdenum as their main component. Furthermore, the first via conductor 31 may be a metal conductor containing tungsten as its main component and the first land conductor 32 a metal conductor containing molybdenum as its main component, or vice versa. The first inner conductor 30 may be a metal conductor containing tungsten or molybdenum as its main component and copper or silver as its main component, or a metal conductor containing copper or gold as its main component and tungsten or molybdenum as its main component.

[0032] In this way, since the wiring board 100 has the first internal conductor 30 in the first insulating substrate 10, compared to conventional wiring boards that have wiring only on a substrate made of organic resin, a material can be selected for the first internal conductor 30 that corresponds to the thermal expansion coefficient of the first insulating substrate 10, thereby providing greater freedom in wiring design.

[0033] The second inner conductor 40 is located inside the second insulating substrate 20. The second inner conductor 40 extends in a direction perpendicular to the third surface 21. Note that "extending" here does not necessarily mean extending over the shortest distance. A portion of the second inner conductor 40 may reach the fourth surface 22 or the second side surface 23. A portion of the second inner conductor 40 may extend in a direction perpendicular to the fourth surface 22 and be electrically connected to the second electrode 120.

[0034] 4 is a diagram showing an example of a cross-sectional view of a portion of the wiring board taken along line B-B shown in FIG. 3 and 4, the second internal conductor 40 has a second via conductor 41 penetrating at least a portion of the second insulating substrate 20 and a second land conductor 42 electrically connected to the second via conductor 41. The second via conductor 41 penetrates one or more resin layers 24. The second land conductor 42 may be located between the multiple resin layers 24. The second land conductor 42 may be a portion located around the second via conductor 41 in a plan view. In other words, the second land conductor 42 may be located at a position overlapping the second via conductor 41 in a plan view.

[0035] The second inner conductor 40 may be, for example, a metal conductor whose main component is copper. Alternatively, the second inner conductor 40 may be a metal conductor whose main components are copper and bismuth. As an example, the second via conductor 41 may be a metal conductor whose main components are copper and bismuth, and the second land conductor 42 may be a metal conductor whose main component is copper, or vice versa.

[0036] The first internal conductor 30 may contain a glass material. In this case, the first internal conductor 30 may be bonded to the first insulating substrate 10, which also contains a glass material, via the glass material. Specifically, the glass material contained in the first internal conductor 30 can be integrated with the glass material contained in the first insulating substrate 10 by firing. This allows the anchor effect between the glass materials to strengthen the bond between the first insulating substrate 10 and the first internal conductor 30.

[0037] Furthermore, when the first internal conductor 30 contains a glass material, the firing temperatures of the first insulating substrate 10 and the first internal conductor 30 can be made closer to each other in the firing process during the manufacturing of the wiring substrate 100. Furthermore, the shrinkage rates of the first insulating substrate 10 and the first internal conductor 30 can be adjusted.

[0038] As shown in FIG. 3 , the interlayer conductor 50 is located on the first surface 11 between the first insulating substrate 10 and the second insulating substrate 20, and electrically connects the conductor located within or on the surface of the first insulating substrate 10 to the conductor located within or on the surface of the second insulating substrate 20. Specifically, the interlayer conductor 50 is electrically connected to the first via conductor 31 and the second via conductor 41. A wiring board 100 having such an interlayer conductor 50 can electrically connect the first via conductor 31 and the second via conductor 41, even if the first via conductor 31 and the second via conductor 41 are not located at the same position in a plan view, as compared to a wiring board 100 not having the interlayer conductor 50. The interlayer conductor 50 may be a metal conductor primarily composed of copper, tungsten, or molybdenum. The interlayer conductor 50 may also contain a glass material.

[0039] The interlayer conductor 50 is located in a place overlapping at least the first via conductor 31 and the second via conductor 41 in a plan view. The interlayer conductor 50 may extend in one or more directions from the periphery of the first via conductor 31 and the second via conductor 41. From another perspective, the interlayer conductor 50 may be in contact with another conductor on the same plane in the horizontal direction.

[0040] The interlayer conductor 50 may include a first conductor layer 51, a second conductor layer 52, and a third conductor layer 53, or may include only the first conductor layer 51. The first conductor layer 51 may be electrically connected to the first internal conductor 30. Specifically, the first conductor layer 51 may be electrically connected to the first via conductor 31. The third conductor layer 53 may be located between the first conductor layer 51 and the second conductor layer 52 and electrically connect the first conductor layer 51 and the second conductor layer 52. The second conductor layer 52 may be located on the third conductor layer 53 and electrically connect to the second internal conductor 40. Specifically, the second conductor layer 52 may be electrically connected to the second via conductor 41. The third conductor layer 53 may be located between the first conductor layer 51 and the second conductor layer 52. The first conductor layer 51 and the first internal conductor 30 may contain the same metal material. The same metal material may be copper, tungsten, or molybdenum. The second internal conductor 40 and the second conductor layer 52 may contain the same metal material, which may be copper, and the third conductor layer 53 may be nickel.

[0041] When the first insulating substrate 10 and the first conductor layer 51 contain a glass material, the anchoring effect of the glass material can increase the bonding strength between the first insulating substrate 10 and the first conductor layer 51. Furthermore, the second internal conductor 40 and the second conductor layer 52, which contain the same metal material, may be bonded by melting and integrating the metal material through heat treatment during the manufacturing process. Furthermore, since the surface of the first conductor layer 51, which contains a glass material, is relatively rough, in other words, has irregularities, the second conductor layer 52 located on the first conductor layer 51 is bonded by the anchoring effect caused by the irregularities on the surface of the first conductor layer 51. In this way, the wiring board 100 according to the present disclosure can increase the bonding strength between the first insulating substrate 10 and the first conductor layer 51, between the second internal conductor 40 and the second conductor layer 52, and between the first conductor layer 51 and the second conductor layer 52. Therefore, the electrical connection between the first insulating substrate 10 and the second insulating substrate 20 is unlikely to be interrupted even if a load is applied to the first conductor layer 51 and the second conductor layer 52, which are the electrical connection portions at the joint between the first insulating substrate 10 and the second insulating substrate 20. Therefore, according to the wiring board 100 of the present disclosure, the reliability of the electrical connection at the joint between the first insulating substrate 10 and the second insulating substrate 20 can be improved, and ultimately the reliability of the electrical connection between the first electrode 110 and the second electrode 120 can be improved.

[0042] 4 , for example, a first internal conductor 30 penetrating the first insulating substrate 10, a second internal conductor 40 penetrating the second insulating substrate 20, and an interlayer conductor 50 electrically connecting the first internal conductor 30 and the second internal conductor 40 are formed inside the first insulating substrate 10 and the second insulating substrate 20. The first internal conductor 30 has a plurality of first via conductors 31 and a first land conductor 32. The plurality of first via conductors 31 extend in a direction perpendicular to the first surface 11 of the first insulating substrate 10 and are connected via a plurality of first land conductors 32 extending in a direction horizontal to the first surface 11. The second internal conductor 40 has a plurality of second via conductors 41 and a second land conductor 42. The plurality of second via conductors 41 extend in a direction perpendicular to the third surface 21 in each of the plurality of resin layers 24 and are connected via a second land conductor 42 extending in a direction horizontal to the third surface 21. The first internal conductor 30 and the second internal conductor 40 are electrically connected by an interlayer conductor 50 between the first insulating substrate 10 and the second insulating substrate 20. A portion of the first internal conductor 30 reaches the second surface 12 and is electrically connected to the first electrode 110. A portion of the second internal conductor 40 reaches the fourth surface 22 and is electrically connected to the second electrode 120.

[0043] <Configuration of First Electrode and Second Electrode According to First Embodiment> The configuration of the first electrode 110 and the second electrode 120 according to the first embodiment will be described with reference to FIGS. 2, 4, and 5. FIG. 5 is a cross-sectional view showing an example of the configuration of the first electrode 110 and the second electrode 120 according to the first embodiment. FIG. 5 is an enlarged view of region C shown in FIG. 4. As shown in FIGS. 2 and 4, the first electrode 110 has a plurality of first metal layers 130. The second electrode 120 has a plurality of second metal layers 140. In the following, the metal layers constituting the first metal layer 130 and the second metal layer 140 may be formed by plating, or a portion may be metal foil.

[0044] As shown in FIGS. 4 and 5 , the multiple first metal layers 130 include a first layer 111, a second layer 112, and a first intermediate portion 131. The first layer 111 is located on the surface of the first electrode 110. The second layer 112 is located in contact with the second surface 12. The first intermediate portion 131 is located between the first layer 111 and the second layer 112 and includes one or more first intermediate layers. In the example of FIGS. 4 and 5 , the first intermediate portion 131 includes a third layer 113, a fourth layer 114, and a fifth layer 115 as first intermediate layers. However, the configuration of the multiple first metal layers 130 is not limited thereto. The number of layers in the first intermediate portion 131 may be one or more.

[0045] The multiple second metal layers 140 include a seventh layer 121, an eighth layer 122, and a second intermediate portion 141. The seventh layer 121 is located on the surface of the second electrode 120. The eighth layer 122 is located in contact with the fourth surface 22. The second intermediate portion 141 is located between the seventh layer 121 and the eighth layer 122 and includes one or more second intermediate layers. In the examples of FIGS. 4 and 5 , the second intermediate portion 141 includes the ninth layer 123 as a second intermediate layer. However, the configuration of the multiple second metal layers 140 is not limited to this. The number of layers in the second intermediate portion 141 may be one or more.

[0046] The number of first metal layers 130 is equal to or greater than the number of second metal layers 140. The greater the number of metal layers included in an electrode, the greater the number of interfaces between the metal layers, and the greater the number of interfaces between the metal layers, the higher the electrical resistance. Therefore, an electrode with a greater number of metal layers is more likely to have high electrical resistance. In other words, an electrode with a greater number of metal layers is more likely to generate heat. In the wiring board 100 according to the embodiment, the thermal conductivity of the first insulating substrate 10 is higher than that of the second insulating substrate 20. The number of second metal layers 140 in the second electrode 120 located on the second insulating substrate 20, which has a lower thermal conductivity than the first insulating substrate 10, is equal to or less than the number of first metal layers 130 in the first electrode 110 located on the first insulating substrate 10. Therefore, the wiring board 100 according to the embodiment can reduce heat generation in the second electrode 120 compared to when the number of metal layers in the second electrode 120 is greater than the number of metal layers in the first electrode 110. Therefore, it is possible to reduce the possibility that the temperature of the second insulating substrate 20 will rise due to heat generation from the electrodes. By reducing the temperature rise of the second insulating substrate 20, it is possible to extend the life of the second insulating substrate 20, and ultimately the life of the wiring substrate 100, for example.

[0047] The first electrode 110 may be located on the second surface 12. The second electrode 120 may be located on the fourth surface 22. In this configuration, the first electrode 110, which generates heat relatively easily, is located on the second surface 12 of the first insulating substrate 10, which has relatively high heat dissipation properties, and the second electrode 120, which generates heat relatively less, is located on the fourth surface 22 of the second insulating substrate 20, which has relatively low heat dissipation properties. This reduces the temperature difference between the second surface 12 and the fourth surface 22, in other words, the temperature difference between the front and back surfaces of the wiring substrate 100. By reducing the temperature difference between the front and back surfaces of the wiring substrate 100, warping of the wiring substrate 100 due to the temperature difference between the front and back surfaces of the wiring substrate 100 is less likely to occur. This makes it less likely for the first electrode 110 to peel off from the second surface 12, and the second electrode 120 to peel off from the fourth surface 22, for example. This makes it possible to obtain a wiring substrate 100 with highly reliable electrical connections. Furthermore, since the flatness of the second surface 12 and the fourth surface 22 is easily maintained, it is possible to obtain a wiring board 100 with high component mounting reliability.

[0048] The plurality of first metal layers 130 may include a first layer 111 located on the surface of the first electrode 110. The first layer 111 may contain a noble metal material as a main component. The ionization series is Li>K>Ca>Na>Mg>Al>Zn>Fe>Ni>Sn>Pb>H ２ > Cu > Hg > Ag > Pt > Au, and among these, lithium (Li) has the highest ionization tendency, and gold (Au) has the lowest ionization tendency. ２ ) is a metal smaller than the metal of the first layer 111. Examples of the first layer 111 include gold (Au), copper (Cu), gold alloy, silver (Ag), palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru), and iridium (Ir). The gold alloy contains gold and may also contain at least one of the metal elements cobalt (Co), nickel (Ni), and tin (Sn). When the first layer 111 contains gold or copper as a main component, the bonding strength with the bonding wire and plating properties are improved. However, the material of the first layer 111 is not limited to these.

[0049] The greater the ionization tendency of a metal, the greater the reactivity. Therefore, by positioning the first layer 111, which is mainly composed of a noble metal material with a relatively small ionization tendency, as the surface layer of the first electrode 110, the corrosion resistance of the first electrode 110 can be improved.

[0050] The plurality of first metal layers 130 may include a first layer 111 located on the surface of the first electrode 110, a second layer 112 located in contact with the second surface 12, and a first intermediate portion 131 located between the first layer 111 and the second layer 112 and including one or more first intermediate layers. The ionization tendency of the metal contained as a main component in the first intermediate layer may be greater than the ionization tendency of the metal contained as a main component in the first layer 111. By positioning the first layer 111 containing a metal with a relatively low ionization tendency as a main component on the first intermediate layer containing a metal with a relatively high ionization tendency as a main component, a first electrode 110 with high corrosion resistance can be obtained.

[0051] The availability of a material with a relatively high ionization tendency indicates that there are many options for the metal material. For example, if only metals with a lower ionization tendency than hydrogen can be selected as the metal material for the first layer 111 and a metal with a higher ionization tendency than hydrogen is selected as the metal material for the first intermediate layer, nickel, for example, can be selected for the first intermediate layer, which can reduce costs, improve heat resistance, and improve adhesion to the second layer 112. Furthermore, if the adhesion between the first layer 111 and the second layer 112 is poor, the first intermediate layer can improve the adhesion between the first layer 111 and the second layer 112 by selecting a material with good adhesion to both the first layer 111 and the second layer 112 for the first intermediate layer.

[0052] The second layer 112 may be a metal conductor containing, for example, copper, tungsten, or molybdenum as a main component. The second layer 112 may contain a glass material. In this case, the second layer 112 may be bonded to the first insulating substrate 10, which also contains a glass material, via the glass material. Specifically, the glass material contained in the second layer 112 can be integrated with the glass material contained in the first insulating substrate 10 by firing. This strengthens the bond between the first insulating substrate 10 and the second layer 112 due to the anchor effect between the glass materials. Furthermore, when the second layer 112 contains a glass material, the firing temperatures of the first insulating substrate 10 and the second layer 112 can be made closer.

[0053] The first intermediate portion 131 includes a third layer 113 as a first intermediate layer, the third layer 113 being positioned in contact with the second layer 112, and the third layer 113 may contain nickel or copper as a main component. The adhesion of the third layer 113 to the second layer 112 may be higher than the adhesion of the first layer 111 to the second layer 112. In this case, by providing the third layer 113 positioned in contact with the second layer 112 between the first layer 111 and the second layer 112, the third layer 113 is less likely to peel from the second layer 112. In this respect, the third layer 113 is more suitable than the first layer 111 as a layer in contact with the second layer 112. Furthermore, by using nickel or copper for the third layer 113, it is possible to reduce material costs compared to replacing the third layer 113 with the precious metal material used for the first layer 111, which is relatively expensive.

[0054] Furthermore, if the plurality of first metal layers 130 consisted only of the first layer 111 and the second layer 112, soldering would be difficult, but by providing the third layer 113 between the first layer 111 and the second layer 112, damage to the first metal layer 130 is reduced, making soldering easier. This ensures a degree of freedom and diversity in the mounting method for semiconductor devices, which will be described later.

[0055] The first intermediate portion 131 includes a fourth layer 114 located between the first layer 111 and the third layer 113 as a first intermediate layer, and the third layer 113 may contain nickel as a main component. The ionization tendency of the metal contained as a main component in the fourth layer 114 may be smaller than the ionization tendency of nickel.

[0056] By covering the third layer 113 with the fourth layer 114, which contains as its main component a material with a lower ionization tendency than the third layer 113, the third layer 113 can be made less susceptible to corrosion. Furthermore, compared to when the first intermediate portion 131 is a single layer, the first intermediate portion 131 is made up of two layers, the third layer 113 and the fourth layer 114. As a result, the first electrode 110, which is more likely to generate heat, is located on the second surface 12 of the first insulating substrate 10, and the second electrode 120, which is less likely to generate heat, is located on the fourth surface 22 of the second insulating substrate 20, which has relatively poor heat dissipation properties. This further reduces the temperature difference between the second surface 12 and the fourth surface 22, making the wiring substrate 100 less likely to warp, and resulting in a wiring substrate 100 with highly reliable electrical connections.

[0057] Furthermore, when the third layer 113 contains nickel as a main component, the heat resistance of the third layer 113 can be increased. Furthermore, when the material of the first layer 111 is a material with low heat resistance, such as gold, the first insulating substrate 10 can be heated at a high temperature after the third layer 113 is coated on the second layer 112 in the manufacturing process. This can improve the adhesion of the third layer 113 to the second layer 112.

[0058] The first intermediate portion 131 includes a fourth layer 114 located between the first layer 111 and the third layer 113 as a first intermediate layer, and the third layer 113 may contain copper as a primary component. The ionization tendency of the metal contained as a primary component in the fourth layer 114 may be greater than the ionization tendency of copper. The fourth layer 114 may be primarily nickel-based and contain no other materials, or may be an alloy containing nickel and phosphorus (P), boron (B), or the like. When the fourth layer 114 is an alloy containing nickel and phosphorus as a primary component, the corrosion resistance of the fourth layer 114 can be improved. Furthermore, the adhesion between the first layer 111, which contains gold as a primary component, and the fourth layer 114 can be enhanced.

[0059] Furthermore, the first intermediate portion 131 may include a fifth layer 115 as a first intermediate layer located between the first layer 111 and the fourth layer 114. The ionization tendency of the metal contained as a main component in the fifth layer 115 may be greater than the ionization tendency of the metal contained as a main component in the fourth layer 114.

[0060] The third layer 113 and the fifth layer 115 may be a metal containing nickel as a main component. In this case, the third layer 113 in contact with the second layer 112 containing tungsten or molybdenum as a main component may be an alloy containing nickel as a main component and boron (B). The fifth layer 115 adjacent to or close to the first layer 111 containing gold as a main component may be an alloy containing nickel as a main component and phosphorus (P).

[0061] When the adhesion between a layer in contact with the surface side of the fifth layer 115, for example, the first layer 111 or the sixth layer described below, and the fourth layer 114 is poor, using a material that has good adhesion to the layer in contact with the surface side for the fifth layer 115 makes the layer in contact with the surface side of the fifth layer 115 less likely to peel off. Furthermore, when the fifth layer 115 is replaced with the precious metal material used for the first layer 111, the precious metal material for the first layer 111 tends to be expensive, so using nickel or the like for the fifth layer 115 can make the material cost cheaper.

[0062] The plurality of second metal layers 140 includes a seventh layer 121 located on the surface of the second electrode 120, and the seventh layer 121 may contain a noble metal material as a main component. The noble metal is, for example, a metal having an ionization tendency similar to that of hydrogen (H ２ ) is a metal having a smaller ionization tendency than the noble metal material. By positioning the seventh layer 121, which is mainly composed of a noble metal material having a relatively low ionization tendency, as a surface layer of the second electrode 120, the corrosion resistance of the second electrode 120 can be improved.

[0063] Examples of the seventh layer 121 include gold (Au), copper (Cu), gold alloy, silver (Ag), palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru), and iridium (Ir). The gold alloy may contain gold and at least one of the metal elements cobalt (Co), nickel (Ni), and tin (Sn). Among the exemplified precious metal materials, the seventh layer 121 may contain gold or copper as a main component, which provides good bonding strength with the bonding wire and plating properties. However, the material of the seventh layer 121 is not limited to these.

[0064] The greater the ionization tendency of a metal, the greater the reactivity. Therefore, by positioning the seventh layer 121, which is mainly composed of a noble metal material with a relatively small ionization tendency, as the surface layer of the second electrode 120, the corrosion resistance of the second electrode 120 can be improved.

[0065] The plurality of second metal layers 140 may include a seventh layer 121 located on the surface of the second electrode 120, an eighth layer 122 located in contact with the fourth surface 22, and a second intermediate portion 141 located between the seventh layer 121 and the eighth layer 122 and including one or more second intermediate layers. The ionization tendency of the metal contained as a main component in the second intermediate layer may be greater than the ionization tendency of the metal contained as a main component in the seventh layer 121. By positioning the seventh layer 121 containing a metal with a relatively low ionization tendency as a main component on the second intermediate layer containing a metal with a relatively high ionization tendency as a main component, the second electrode 120 can have high corrosion resistance.

[0066] The availability of a material with a relatively high ionization tendency indicates a wide range of metal material options. For example, if only metals with a lower ionization tendency than hydrogen can be selected for the seventh layer 121 and a metal with a higher ionization tendency than hydrogen is selected for the second intermediate layer, nickel, for example, can be selected for the second intermediate layer. Depending on the material conditions, this can result in cost reduction, improved heat resistance, and improved adhesion to the eighth layer 122. Furthermore, if the seventh layer 121 and the eighth layer 122 have poor adhesion, but the second intermediate layer has good adhesion to both the seventh layer 121 and the eighth layer 122, the second intermediate layer is effective in improving adhesion between the second metal layers.

[0067] The second intermediate portion 141 includes a ninth layer 123 as a second intermediate layer located in contact with the eighth layer 122, and the ninth layer 123 may contain nickel as a main component. The ninth layer 123 may contain nickel as a main component and may not contain other materials, or may be an alloy of nickel containing phosphorus (P), boron (B), or the like.

[0068] The pattern of the laminate of the second insulating substrate 20 made of resin or the like, the seventh layer 121 made of Au or the like, and the eighth layer 122 made of copper foil or the like has low hardness, so it may be difficult to connect it to a bonding wire or a conductive adhesive (for example, solder). In contrast, by providing one or more second intermediate layers made of nickel or the like between the seventh layer 121 and the eighth layer 122, the hardness of the pattern can be increased, making it easier to connect it to a bonding wire or a conductive adhesive.

[0069] Furthermore, the seventh layer 121 made of Au or the like has low adhesion to the eighth layer 122 made of copper foil or the like. On the other hand, if the ninth layer 123 made of nickel or the like has good adhesion to the eighth layer 122 made of copper foil or the like, the ninth layer 123 is less likely to peel off from the eighth layer 122 due to the high adhesion between the eighth layer 122 and the ninth layer 123. In other words, the ninth layer 123 is more suitable than the seventh layer 121 as a layer in contact with the eighth layer 122. Furthermore, if the ninth layer 123 is replaced with the precious metal material used for the seventh layer 121, the precious metal material for the seventh layer 121 tends to be expensive, so using nickel for the ninth layer 123 can reduce material costs.

[0070] An example of the thickness in the Z direction of each layer of the first electrode 110, the second electrode 120, and the interlayer conductor 50 will be described with reference to FIG. 5. As shown in FIG. 5, the thickness of the first layer 111 of the first electrode 110 is 0.1 μm to 1.0 μm. The thickness of the second layer 112 is 5.0 μm to 30.0 μm. The thickness of the third layer 113 is 0.1 μm to 2.0 μm. The thickness of the fourth layer 114 is 2.0 μm to 10.0 μm. The thickness of the fifth layer 115 is 1.0 μm to 10.0 μm.

[0071] The seventh layer 121 of the second electrode 120 has a thickness of 0.1 μm to 1.0 μm, the eighth layer 122 has a thickness of 7.0 μm to 100 μm, and the ninth layer 123 has a thickness of 1.0 μm to 10.0 μm.

[0072] The interlayer conductor 50 has a first conductor layer 51 having a thickness of 5.0 μm to 30.0 μm, a second conductor layer 52 having a thickness of 2.0 μm to 10.0 μm, and a third conductor layer 53 having a thickness of 0.1 μm to 2.0 μm.

[0073] The positions and dimensions of the first electrode 110 and the second electrode 120 are not limited to the configurations shown in FIGS. 4 and 5 . Next, other configuration examples of the first electrode 110 and the second electrode 120 according to the second to fifth embodiments will be described. Of the multiple first metal layers 130 included in the first electrode 110 according to the second to fifth embodiments, the configurations of the first layer 111 and the second layer 112 are as described above. Furthermore, of the multiple second metal layers 140 included in the second electrode 120, the configurations of the seventh layer 121 and the eighth layer 122 are as described above. Therefore, the following description will focus on the first intermediate portion 131 located between the first layer 111 and the second layer 112, and the second intermediate portion 141 located between the seventh layer 121 and the eighth layer 122, and will omit a description of the other configurations of the first metal layer 130 and the second metal layer 140 other than the first intermediate portion 131 and the second intermediate portion 141.

[0074] <Configuration of First Electrode and Second Electrode According to Second Embodiment> The configuration of the first electrode 110 and the second electrode 120 according to the second embodiment will be described with reference to Fig. 6A. Fig. 6A is a cross-sectional view showing an example of the configuration of the first electrode 110 and the second electrode 120 according to the second embodiment.

[0075] In the second embodiment, the first intermediate portion 131 includes a third layer 113 located in contact with the second layer 112 as a first intermediate layer, and the third layer 113 may contain nickel or copper as a main component. The second intermediate portion 141 includes a ninth layer 123 located in contact with the eighth layer 122 as a second intermediate layer, and the ninth layer 123 may contain nickel as a main component. In this case, the number of layers of the first metal layer 130 is three, the number of layers of the second metal layer 140 is three, and the number of layers of the first metal layer 130 is the same as the number of layers of the second metal layer 140. More specifically, when the number of layers of the first metal layer 130 is the same as the number of layers of the second metal layer 140, and the third layer 113 is mainly composed of nickel, the third layer 113 may contain phosphorus.

[0076] <Configuration of First Electrode and Second Electrode According to Third Embodiment> Another configuration of the multiple first metal layers 130 of the first electrode 110 and the multiple second metal layers 140 of the second electrode 120 according to the third embodiment will be described with reference to Fig. 6B. Fig. 6B is a cross-sectional view showing an example of the configuration of the first electrode 110 and the second electrode 120 according to the third embodiment.

[0077] In the third embodiment, the first intermediate portion 131 includes, as first intermediate layers, a third layer 113 located in contact with the second layer 112 and a fourth layer 114 located between the first layer 111 and the third layer 113, and the third layer 113 may contain nickel or copper plating as a main component. When the third layer 113 contains nickel as a main component, the fourth layer 114 may contain copper plating as a main component. When the third layer 113 contains copper plating as a main component, the fourth layer 114 may contain nickel as a main component. The second intermediate portion 141 includes, as a second intermediate layer, a ninth layer 123 located in contact with the eighth layer 122, and the ninth layer 123 may contain nickel as a main component. In this case, the number of layers of the first metal layer 130 is four, and the number of layers of the second metal layer 140 is three, so the number of layers of the first metal layer 130 is greater than the number of layers of the second metal layer 140 .

[0078] <Configuration of First Electrode and Second Electrode According to Fourth Embodiment> Another configuration of the multiple first metal layers 130 of the first electrode 110 and the multiple second metal layers 140 of the second electrode 120 according to the fourth embodiment will be described with reference to Fig. 6C. Fig. 6C is a cross-sectional view showing an example of the configuration of the first electrode 110 and the second electrode 120 according to the fourth embodiment.

[0079] In the fourth embodiment, the first intermediate section 131 may include, as first intermediate layers, a third layer 113 located in contact with the second layer 112, and a fourth layer 114, a fifth layer 115, and a sixth layer 116 located between the first layer 111 and the third layer 113 and in that order from the third layer 113 toward the first layer 111. That is, the first intermediate section 131 of the fourth embodiment further includes, as a first intermediate layer, a sixth layer 116 located between the first layer 111 and the fifth layer 115 in addition to the first intermediate section 131 shown in FIGS. 4 and 5 . The ionization tendency of the metal contained as a main component in the sixth layer 116 may be smaller than the ionization tendency of the metal contained as a main component in the fifth layer 115 or may be larger than the ionization tendency of the metal contained as a main component in the first layer 111. The sixth layer 116 may contain palladium (Pd) as a main component. The corrosion resistance of the first electrode 110 can be further improved by positioning the sixth layer 116 between the first layer 111 and the fifth layer 115, the sixth layer 116 being mainly composed of a metal that has a lower ionization tendency than the metal contained as the main component in the fifth layer 115.

[0080] 4 and 5 , the second intermediate portion 141 of the fourth embodiment may further include a tenth layer 124 located between the seventh layer 121 and the ninth layer 123. The ionization tendency of the metal contained as a main component in the tenth layer 124 may be smaller than that of the metal contained as a main component in the ninth layer 123, or may be larger than that of the metal contained as a main component in the seventh layer 121. The tenth layer 124 may contain palladium (Pd) as a main component. The corrosion resistance of the second electrode 120 can be further improved by positioning the tenth layer 124, which is mainly composed of a metal having a smaller ionization tendency than that of the metal contained as a main component in the ninth layer 123, between the seventh layer 121 and the ninth layer 123. In this case, the number of layers of the first metal layer 130 is six, and the number of layers of the second metal layer 140 is four, so the number of layers of the first metal layer 130 is greater than the number of layers of the second metal layer 140 .

[0081] <Configuration of First Electrode and Second Electrode According to Fifth Embodiment> Another configuration of the plurality of first metal layers 130 of the first electrode 110 and the plurality of second metal layers 140 of the second electrode 120 according to the fifth embodiment will be described with reference to Fig. 6D. Fig. 6D is a cross-sectional view showing an example of the configuration of the first electrode 110 and the second electrode 120 according to the fifth embodiment.

[0082] In the fifth embodiment, the second layer 112 of the first electrode 110 may be at least partially covered with an insulating member 117. The insulating member 117 may be made of a material such as alumina (Al ２ O ３ ) By covering at least a portion of the second layer 112 with the insulating member 117, it is possible to improve the adhesion between the first insulating substrate 10 and the second layer 112. Note that "at least a portion of" the second layer 112 is covered with the insulating member 117 includes the case where at least the side surface of the second layer 112 is covered. However, "at least a portion of" the second layer 112 is covered with the insulating member 117 is not limited to this, and the insulating member 117 may cover a part or all of the surface of the second layer 112. Note that the material constituting the insulating member 117 may be the same as the material constituting the first insulating substrate 10.

[0083] The insulating member 117 may contain a glass material. In this case, the insulating member 117 may be bonded to the first insulating substrate 10 or the second layer 112, which also contain a glass material, via the glass material. Specifically, the glass material contained in the insulating member 117 can be integrated with the glass material contained in the first insulating substrate 10 or the second layer 112 by firing. This allows the anchor effect between the glass materials to strengthen the bonds between the insulating member 117 and the first insulating substrate 10, and between the insulating member 117 and the second layer 112.

[0084] Furthermore, when insulating member 117 contains a glass material, the firing temperatures of insulating member 117 and first insulating substrate 10, and insulating member 117 and second layer 112 can be made closer to each other during the firing process in manufacturing wiring substrate 100.

[0085] 7 is a perspective view showing an example of the configuration of a semiconductor device according to the embodiment. As shown in FIG. 7, the semiconductor device 300 includes a wiring substrate 100, a semiconductor element 310, and an optical filter 320.

[0086] The semiconductor element 310 is mounted on the wiring board 100. In the example shown in Fig. 7 , the semiconductor element 310 is mounted on the third surface 21 of the second insulating substrate 20 in the wiring board 100. The semiconductor element 310 is located inside the through hole 200. In the example shown in Fig. 7 , the optical filter 320 is mounted on the fourth surface 22 of the second insulating substrate 20 in the wiring board 100. The optical filter 320 faces the open end of the through hole 200 on the fourth surface 22.

[0087] The semiconductor element 310 is, for example, a sensor element such as an image sensor, a light-emitting element, or an integrated circuit (IC). The semiconductor element 310 is electrically connected to the wiring substrate 100 by soldering, and may be flip-chip mounted or die-attach mounted, or may be electrically connected by bonding wire. The optical filter 320 may face the open end of the through-hole 200 on the second surface 12, depending on the orientation of the light-irradiated surface of the semiconductor element 310, etc.

[0088] The first insulating substrate 10 may contain an organic resin, and the second insulating substrate 20 may contain ceramic. That is, the semiconductor element 310 may be mounted on the second insulating substrate 20 containing ceramic.

[0089] 8 is a cross-sectional perspective view showing another example of the wiring substrate according to the embodiment. The wiring substrate 100a shown in Fig. 8 is structurally different from the wiring substrate 100 shown in Fig. 2 in that the wiring substrate 100a has a first electrode 110a in addition to the first electrode 110.

[0090] The through hole 200 is formed in a rectangular shape with the portion that penetrates the second insulating substrate 20 being larger in the horizontal direction than the portion that penetrates the first insulating substrate 10. Therefore, when the wiring substrate 100 is viewed in plan, the inner periphery 11a of the first surface 11 of the first insulating substrate 10 is exposed in the through hole 200. Two first electrodes 110a are located on this inner periphery 11a, between the second electrode 120 and the through hole 200.

[0091] The through hole 200 that penetrates the second insulating substrate 20 does not have to penetrate the first insulating substrate 10. In this case, too, the first electrode 110a can be positioned in the through hole 200 in a portion where the first surface 11 of the first insulating substrate 10 is exposed. Furthermore, the through hole 200 that penetrates the second insulating substrate 20 may penetrate only a portion of the multiple ceramic layers 14. In this case, the first electrode 110a can be positioned in the through hole 200 in a portion where the first insulating substrate 10 is exposed.

[0092] The wiring substrate 100a may have both the first electrode 110 and the first electrode 110a, or may have either the first electrode 110 or the first electrode 110a. For example, the wiring substrate 100a may not have the first electrode 110, but may have the first electrode 110a and the second electrode 120, with the first electrode 110a and the second electrode 120 being electrically connected. For example, the wiring substrate 100a may have the first electrode 110, the first electrode 110a, and the second electrode 120, with the first electrode 110 and the second electrode 120 being electrically connected, and the first electrode 110a and the second electrode 120 being electrically connected.

[0093] <Configuration of First Electrode and Second Electrode According to Sixth Embodiment> The configuration of the first electrode 110 and the second electrode 120 according to the sixth embodiment will be described with reference to Fig. 9. Fig. 9 is a cross-sectional view showing an example of the configuration of the first electrode 110 and the second electrode 120 according to the sixth embodiment.

[0094] As shown in FIG. 9 , the wiring board 100 according to the sixth embodiment differs from the other embodiments in its cross-sectional shape. Specifically, the fourth surface 22 of the second insulating substrate 20 may have a protruding convex portion 20A at the connection point between the second electrode 120 and the eighth layer 122. In this case, the end 120U of the second electrode 120 may be oriented toward the inside of the wiring board 100. More specifically, the end 120U may be partially rounded along the protruding portion 20A. Furthermore, the end 120U may be shaped to cover at least a portion of the protruding portion 20A. By having the protruding convex portion 20A on the fourth surface 22 of the second insulating substrate 20, a portion of the second electrode 120 is partially gripped by the protruding portion 20A, thereby improving the bonding strength between the second electrode 120 and the second insulating substrate 20. This reduces the likelihood of the second electrode 120 peeling off from the second insulating substrate 20 even when an impact is applied to the wiring board 100.

[0095] When the end portion 120U of the second electrode 120 has the above-described configuration, it is sufficient that the eighth layer 122 is located at least on the protruding portion 20A as described above. However, the second intermediate portion 141 including the ninth layer 123 and the seventh layer 121, which is the outermost layer of the second electrode 120, may be shaped to conform to the eighth layer 122. Furthermore, at least one of the seventh layer 121 and the ninth layer 123 may be in contact with the protruding portion 20A. That is, at least one of the seventh layer 121 and the ninth layer 123 may extend further from the eighth layer 122 located on the protruding portion 20A to cover the protruding portion 20A. With this configuration, the interface between the eighth layer 122, which is the lowest layer, and the second insulating substrate 20 is covered by at least one of the seventh layer 121 and the ninth layer 123, which extend therefrom. This reduces the possibility of moisture or dust penetrating the interface between the eighth layer 122 and the second insulating substrate 20. This reduces the possibility that the interface between the eighth layer 122 and the second insulating substrate 20 will widen, widening the gap, or that the eighth layer 122 will corrode, causing the second electrode 120 to fall off.

[0096] 9 , the second via conductor 41 may expand in a planar direction intersecting the thickness direction near the middle between the second land conductor 42 and the eighth layer 122. In particular, if an alloy is formed at the interface between the eighth layer 122 and the second via conductor 41, even if a force is applied in a direction that would cause the second electrode 120 to peel off, the expanded portion of the second via conductor 41 will be caught within the second insulating substrate 20 due to the above configuration, thereby reducing the possibility that the second via conductor 41 and the second electrode 120 will fall off or be damaged and break.

[0097] When the eighth layer 122 is mainly composed of copper, the second via conductor 41 may contain copper and tin. In this case, the weight percentage of copper contained in the second via conductor 41 may be 15% or more and 45% or less, and the weight percentage of tin contained in the second via conductor 41 may be 35% or more and 55% or less.

[0098] Furthermore, the second via conductor 41 may contain 1% to 10% by weight of resin. This configuration can impart fluidity to the second via conductor 41. Furthermore, the bonding strength between the second insulating substrate 20, which contains a resin as an organic material, and the second via conductor 41 can be improved. The resin contained in the second via conductor 41 and the resin contained in the second insulating substrate 20 may be the same. This configuration can improve the bonding strength between the second via conductor 41 and the second insulating substrate 20. The weight percentage of the resin contained in the second insulating substrate 20 may be greater than the weight percentage of the resin contained in the second via conductor 41. The resin contained in the second via conductor 41 may be an epoxy resin.

[0099] Furthermore, the second via conductor 41 may contain at least one of bismuth and indium. In this case, when the second via conductor 41 contains tin and bismuth, the tin contained in the second via conductor 41 may exist as a eutectic with the bismuth.

[0100] The second land conductor 42 may contain, for example, copper, and more specifically, may be made of copper foil. That is, the second land conductor 42 may contain 70% or more by weight of copper of the entire second land conductor 42.

[0101] 9 , the second land conductor 42 may have a trapezoidal shape in a cross-sectional view. More specifically, the width of the second land conductor 42 may decrease toward the first insulating substrate 10. With this configuration, when the second insulating substrate 20 is stacked on the first insulating substrate 10, the pressure applied to the second land conductor 42 can be easily controlled in the direction of the first insulating substrate 10, and the second land conductor 42 and the second via conductor 41 can be more reliably contacted.

[0102] On the other hand, the second layer 112 of the first electrode 110 may have a thickness that decreases with increasing distance from the first via conductor 31 in a cross-sectional view, as shown in FIG. 9 . In this case, the insulating member 117 may cover the edge of the second layer 112. Furthermore, the first intermediate portion 131 and the first layer 111 may be warped to match the shape of the portion of the second layer 112 that is not covered with the insulating member 117. Furthermore, at least one of the first intermediate portion 131 and the first layer 111 may be in contact with the insulating member 117.

[0103] Further advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

[0104] The present technology can be configured as follows: (1) A wiring board comprising: a first insulating substrate containing a ceramic material; a second insulating substrate containing a resin material and bonded to the first insulating substrate; a first electrode located on a surface of the first insulating substrate other than a bonding portion with the second insulating substrate and having a plurality of first metal layers; and a second electrode located on a surface of the second insulating substrate other than a bonding portion with the first insulating substrate and having a plurality of second metal layers, wherein the number of first metal layers is equal to or greater than the number of second metal layers. (2) The wiring board according to (1), wherein the first insulating substrate has a first surface and a second surface opposite the first surface, the second insulating substrate has a third surface in contact with the first surface and a fourth surface opposite the third surface, the first electrode is located on the second surface, and the second electrode is located on the fourth surface. (3) The wiring board according to (1) or (2), wherein the plurality of first metal layers include a first layer located on a surface of the first electrode, and the first layer contains a precious metal material as a main component. (4) The wiring board according to (2), wherein the plurality of first metal layers include: a first layer located on a surface of the first electrode; a second layer located in contact with the second surface; and a first intermediate portion located between the first layer and the second layer and including one or more first intermediate layers, and wherein the ionization tendency of the metal contained as a main component in the first intermediate layer is greater than the ionization tendency of the metal contained as a main component in the first layer. (5) The wiring board according to (4), wherein the first intermediate portion includes a third layer located in contact with the second layer as the first intermediate layer, and the third layer contains nickel or copper as a main component. (6) The wiring board according to (5), wherein the first intermediate portion includes a fourth layer located between the first layer and the third layer as the first intermediate layer, the third layer contains nickel as a main component, and the ionization tendency of the metal contained as a main component in the fourth layer is smaller than the ionization tendency of the nickel.(7) The wiring board according to (5), wherein the first intermediate portion includes a fourth layer located between the first layer and the third layer as the first intermediate layer, the third layer containing copper as a main component, and the ionization tendency of the metal contained as a main component in the fourth layer is greater than the ionization tendency of the copper. (8) The wiring board according to (6), wherein the first intermediate portion includes a fifth layer located between the first layer and the fourth layer as the first intermediate layer, and the ionization tendency of the metal contained as a main component in the fifth layer is greater than the ionization tendency of the metal contained as a main component in the fourth layer. (9) The wiring board according to (8), wherein the first intermediate portion includes a sixth layer located between the first layer and the fifth layer as the first intermediate layer, and the ionization tendency of the metal contained as a main component in the sixth layer is less than the ionization tendency of the metal contained as a main component in the fifth layer. (10) The wiring board according to any one of (1) to (9), wherein the plurality of second metal layers include a seventh layer located on a surface of the second electrode, and the seventh layer contains a precious metal material as a main component. (11) The wiring board according to (2), wherein the plurality of second metal layers include: a seventh layer located on a surface of the second electrode; an eighth layer located in contact with the fourth surface; and a second intermediate portion located between the seventh layer and the eighth layer and including one or more second intermediate layers, and wherein the ionization tendency of the metal contained as a main component in the second intermediate layer is greater than the ionization tendency of the metal contained as a main component in the seventh layer. (12) The wiring board according to (11), wherein the second intermediate portion includes a ninth layer located in contact with the eighth layer as the second intermediate layer, and the ninth layer contains nickel as a main component. (13) The wiring board according to (12), wherein the second intermediate portion includes a tenth layer located between the seventh layer and the ninth layer, and the ionization tendency of the metal contained as a main component in the tenth layer is lower than the ionization tendency of the metal contained as a main component in the ninth layer. (14) The wiring board according to any one of (4) to (9), wherein the second layer is at least partially covered with an insulating member.(15) The wiring board according to any one of (2), (4) to (9), and (11) to (14), comprising: a first internal conductor located inside the first insulating substrate, a first conductor layer located on the first surface and electrically connected to the first internal conductor, a second conductor layer located on the first conductor layer, and a second internal conductor located inside the second insulating substrate and electrically connected to the second conductor layer, wherein the thermal conductivity of the first insulating substrate is higher than the thermal conductivity of the second insulating substrate, the first conductor layer contains a glass material, and the second internal conductor and the second conductor layer contain the same metal material. (16) A semiconductor device comprising: the wiring board according to any one of (1) to (15), and a semiconductor element mounted on the wiring board.

[0105] REFERENCE SIGNS LIST 10 First insulating substrate 11 First surface 12 Second surface 20 Second insulating substrate 20A Convex portion 21 Third surface 22 Fourth surface 30 First internal conductor 40 Second internal conductor 50 Interlayer conductor 51 First conductor layer 52 Second conductor layer 53 Third conductor layer 100 Wiring substrate 110 First electrode 111 First layer 112 Second layer 113 Third layer 114 Fourth layer 115 Fifth layer 116 Sixth layer 117 Insulating member 120 Second electrode 120U End portion 121 Seventh layer 122 Eighth layer 123 Ninth layer 124 Tenth layer 130 First metal layer 131 First intermediate portion 140 Second metal layer 141 Second intermediate portion 300 Semiconductor device

Claims

1. A wiring board comprising: a first insulating substrate containing a ceramic material; a second insulating substrate containing a resin material and bonded to the first insulating substrate; a first electrode having a plurality of first metal layers located on the surface of the first insulating substrate other than the bonding area with the second insulating substrate; and a second electrode having a plurality of second metal layers located on the surface of the second insulating substrate other than the bonding area with the first insulating substrate, wherein the number of first metal layers is equal to or greater than the number of second metal layers.

2. The wiring board according to claim 1, wherein the first insulating substrate has a first surface and a second surface located opposite the first surface, the second insulating substrate has a third surface located in contact with the first surface and a fourth surface located opposite the third surface, the first electrode is located on the second surface, and the second electrode is located on the fourth surface.

3. The wiring board according to claim 1 or 2, wherein the plurality of first metal layers include a first layer located on the surface of the first electrode, and the first layer contains a noble metal material as a main component.

4. The wiring board described in claim 2, wherein the plurality of first metal layers have: a first layer located on the surface of the first electrode; a second layer located in contact with the second surface; and a first intermediate portion located between the first layer and the second layer and including one or more first intermediate layers, and the ionization tendency of the metal contained as a main component in the first intermediate layer is greater than the ionization tendency of the metal contained as a main component in the first layer.

5. The wiring board according to claim 4, wherein the first intermediate portion includes a third layer positioned in contact with the second layer as the first intermediate layer, and the third layer contains nickel or copper as a main component.

6. The wiring board according to claim 5, wherein the first intermediate portion includes a fourth layer located between the first layer and the third layer as the first intermediate layer, the third layer contains nickel as a main component, and the ionization tendency of the metal contained as a main component in the fourth layer is smaller than the ionization tendency of the nickel.

7. The wiring board according to claim 5, wherein the first intermediate portion includes a fourth layer located between the first layer and the third layer as the first intermediate layer, the third layer contains copper as a main component, and the ionization tendency of the metal contained as a main component in the fourth layer is greater than the ionization tendency of the copper.

8. The wiring board according to claim 6, wherein the first intermediate portion includes a fifth layer located between the first layer and the fourth layer as the first intermediate layer, and the ionization tendency of the metal contained as a main component in the fifth layer is greater than the ionization tendency of the metal contained as a main component in the fourth layer.

9. The wiring board according to claim 8, wherein the first intermediate portion includes a sixth layer located between the first layer and the fifth layer as the first intermediate layer, and the ionization tendency of the metal contained as a main component in the sixth layer is smaller than the ionization tendency of the metal contained as a main component in the fifth layer.

10. A wiring board according to any one of claims 1 to 9, wherein the plurality of second metal layers include a seventh layer located on the surface of the second electrode, and the seventh layer contains a noble metal material as a main component.

11. The wiring board described in claim 2, wherein the plurality of second metal layers include a seventh layer located on the surface of the second electrode, an eighth layer located in contact with the fourth surface, and a second intermediate portion located between the seventh layer and the eighth layer and including one or more second intermediate layers, and wherein the ionization tendency of the metal contained as a main component in the second intermediate layer is greater than the ionization tendency of the metal contained as a main component in the seventh layer.

12. The wiring board according to claim 11, wherein the second intermediate portion includes a ninth layer positioned in contact with the eighth layer as the second intermediate layer, and the ninth layer contains nickel as a main component.

13. The wiring board described in claim 12, wherein the second intermediate portion includes a tenth layer located between the seventh layer and the ninth layer, and the ionization tendency of the metal contained as a main component in the tenth layer is smaller than the ionization tendency of the metal contained as a main component in the ninth layer.

14. The wiring board according to any one of claims 4 to 9, wherein the second layer is at least partially covered with an insulating member.

15. A wiring board as described in any one of claims 2, 4 to 9, and 11 to 14, comprising: a first internal conductor located inside the first insulating substrate; a first conductor layer located on the first surface and electrically connected to the first internal conductor; a second conductor layer located on the first conductor layer; and a second internal conductor located inside the second insulating substrate and electrically connected to the second conductor layer, wherein the thermal conductivity of the first insulating substrate is higher than the thermal conductivity of the second insulating substrate, the first conductor layer contains a glass material, and the second internal conductor and the second conductor layer contain the same metal material.

16. A semiconductor device comprising: a wiring board according to any one of claims 1 to 15; and a semiconductor element mounted on the wiring board.

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