Wiring board and semiconductor device

Abstract

The present invention comprises a first insulating substrate, a second insulating substrate, a first internal conductor, a first conductor layer, a second conductor layer, and a second internal conductor. The first insulating substrate has a first surface and contains a glass material. The second insulating substrate is positioned partially in contact with the first surface and contains a resin material. The first internal conductor is located in the first insulating substrate. The first conductor layer is positioned on the first surface and is electrically connected to the first internal conductor. The second conductor layer is positioned on the first conductor layer. The second internal conductor is located in the second insulating substrate and is electrically connected to the second conductor layer. 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. The second internal conductor and the second conductor layer contain the same metallic material.

Description

Wiring board and semiconductor device

[0001] The present disclosure relates 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 comprises a first insulating substrate, a second insulating substrate, a first internal conductor, a first conductor layer, a second conductor layer, and a second internal conductor. The first insulating substrate has a first surface and contains a glass material. The second insulating substrate is located in contact with a portion of the first surface and contains a resin material. The first internal conductor is located within the first insulating substrate. The first conductor layer is located on the first surface and is electrically connected to the first internal conductor. The second conductor layer is located on the first conductor layer. The second internal conductor is located within the second insulating substrate and is electrically connected to the second conductor layer. 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. The second internal conductor and the second conductor layer contain the same metal material.

[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 plan view showing an example of the configuration of a wiring board according to an embodiment. FIG. 3 is a cross-sectional perspective view taken along line A-A shown in FIG. 1. FIG. 4 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. 5 is a perspective view showing an example of the configuration of a semiconductor device according to an embodiment. FIG. 6 is a cross-sectional perspective view showing an example of the configuration of a semiconductor device according to an 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 as long as the processing content is not contradictory. Furthermore, the same components in the following embodiments will be assigned the same reference numerals, and redundant explanations will 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] The resin substrate portion, which is a substrate containing resin, and the ceramic substrate portion, which is a substrate containing ceramic, have different thermal expansion coefficients. Therefore, when the resin substrate portion and the ceramic substrate portion repeatedly undergo thermal expansion and contraction due to, for example, heat treatment during the manufacturing process or heat generated during operation of the mounted electronic components, a load is applied to the electrical connection at the joint between the resin substrate portion and the ceramic substrate portion. Even in such cases, it is desired to reduce the possibility of the electrical connection between the resin substrate portion and the ceramic substrate portion being interrupted.

[0009] As described above, the above-mentioned prior art has room for further improvement in terms of improving the reliability of the electrical connection at the joint between the resin substrate portion and the ceramic substrate portion.

[0010] Here, we have given an example of a wiring board in which a substrate containing a resin and a substrate containing a ceramic are bonded together, but this is not limited to this, and the above-mentioned requirements are also required when two insulating substrates made of different materials are bonded together.

[0011] The present disclosure provides a technique that can improve the reliability of electrical connection at the joint between two insulating substrates.

[0012] <Embodiment> Fig. 1 is a perspective view showing an example of the configuration of a wiring board according to an embodiment. Fig. 2 is a plan view showing an example of the configuration of a wiring board according to an embodiment. Fig. 3 is a cross-sectional perspective view taken along line AA shown in Fig. 1.

[0013] As shown in FIGS. 1 to 3, the wiring board 100 according to the embodiment includes a first insulating substrate 10, a second insulating substrate 20, a first inner conductor 30, a second inner conductor 40, and an interlayer conductor 50.

[0014] The wiring substrate 100 is a laminate of a first insulating substrate 10 and a second insulating substrate 20. The first insulating substrate 10 may contain an inorganic material. The inorganic material may be ceramic. The second insulating substrate 20 may contain an organic material. The organic material may be an organic resin or may contain multiple types of organic resins. The thermal conductivity of the first insulating substrate 10 is higher than that of the second insulating substrate 20. The detailed configurations of the first internal conductors 30, the second internal conductors 40, and the interlayer conductors 50 will be described later with reference to FIG. 4 . In addition, the planar view in this disclosure refers to a planar view seen from a direction perpendicular to the first surface 11 of the first insulating substrate 10, and includes a planar perspective view in which some components are seen through from the Z direction. In addition, the horizontal direction in this disclosure refers to the XY plane direction.

[0015] The wiring substrate 100 may be rectangular in plan view, for example. The wiring substrate 100 may also have a through hole 110 in the center in plan view. The through hole 110 may be rectangular in plan view. The through hole 110 may be configured in a rectangular shape such that the portion that penetrates the first insulating substrate 10 is larger in the horizontal direction than the portion that penetrates the second insulating substrate 20. Without being limited to the above, the wiring substrate 100 may be configured without the through hole 110.

[0016] Ceramics have higher rigidity than organic materials. Therefore, a wiring board 100 configured with a first insulating substrate 10 containing ceramic and a second insulating substrate 20 containing an organic material can have improved rigidity compared to a wiring board configured only with a substrate containing an organic material. This makes it easy for the wiring board 100 to maintain its rigidity even when the thickness of the wiring board 100 is reduced, without the need for additional reinforcing members. Furthermore, the improved rigidity of the wiring board 100 due to the above configuration reduces the likelihood of the wiring board 100 flexing, warping, or bending.

[0017] Furthermore, the wiring board 100 can be made lighter because the volumes of the first insulating substrate 10 and the second insulating substrate 20 can be reduced by the amount of the through holes 110 .

[0018] <First Insulating Substrate> The first insulating substrate 10 may contain ceramic, or may be primarily composed of ceramic. Examples of ceramic that can be used include ceramics primarily composed of at least one selected from the group consisting of aluminum oxide, silicon oxide, zirconium oxide, silicon carbide, silicon nitride, and aluminum nitride, or ceramics primarily composed of a composite oxide such as mullite, zircon, steatite, enstatite, glass ceramics, and glass. The first insulating substrate 10 contains a glass material in addition to the ceramic. In the present disclosure, a "major component" refers to a material that accounts for, for example, 50% by mass or more of the material.

[0019] The first insulating substrate 10 may be an insulating substrate made of a glass substrate, which contains a glass material in the same manner as an insulating substrate containing ceramic.

[0020] 3 , the first insulating substrate 10 may have a first surface 11 and a second surface 12 located on the opposite side to 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.

[0021] The first insulating substrate 10 may also 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 in this manner, it is possible to obtain a first insulating substrate 10 that has therein first land conductors 32 (see FIG. 4 ), which will be described later, and conductors having wiring shapes suitable for various purposes. Furthermore, by making the plurality of ceramic layers 14 each have a different shape, it is possible to improve the degree of freedom in designing the shape of the wiring substrate 100.

[0022] The wiring board 100 having such a first insulating substrate 10 offers a high degree of freedom in wiring design. Furthermore, by configuring the first insulating substrate 10 using a plurality of ceramic layers 14, it is possible to fabricate the first insulating substrate 10 while checking, layer by layer, whether the first land conductors 32 (described later) and internal conductors having wiring shapes according to various purposes are properly formed, and whether each layer has been processed into the desired shape. This allows for an improved yield of the first insulating substrate 10.

[0023] In this embodiment, the first insulating substrate 10 has two ceramic layers 14, but the number of ceramic layers 14 is not limited to two. The number of ceramic layers 14 may be three or more. Furthermore, the first insulating substrate 10 does not necessarily have a multi-layer structure. That is, the first insulating substrate 10 may be a single layer. When the first insulating substrate 10 is a single layer, the first insulating substrate 10 and the first land conductors 32 can be formed by additive manufacturing (AM) using a 3D printer.

[0024] <Second Insulating Substrate> As described above, the second insulating substrate 20 may contain an organic material. The organic 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. Furthermore, the second insulating substrate 20 may contain multiple types of organic resins.

[0025] The organic resin may be, for example, polytetrafluoroethylene (PTFE) or other fluororesin, or polyphenylene ether resin. The second insulating substrate 20 may contain components other than the organic resin. Examples of components other than the organic resin contained in the second insulating substrate 20 include inorganic materials such as silica and rubber materials. The content of the inorganic material such as silica in the second insulating substrate 20, in terms of mass %, may be greater than the content of the organic resin in the second insulating substrate 20. More specifically, the content of the inorganic material such as silica in the second insulating substrate 20 may be 50 mass % or more of the second insulating substrate 20, and the content of the organic resin in the second insulating substrate 20 may be 50 mass % or less of the second insulating substrate 20.

[0026] 3 , the second insulating substrate 20 may have a third surface 21 and a fourth surface 22 located opposite the third surface 21. 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 the outer surface of the second insulating substrate 20.

[0027] The second insulating substrate 20 may have multiple organic resin layers 24. The multiple organic resin layers 24 may be stacked along the thickness direction of the second insulating substrate 20. By configuring the second insulating substrate 20 using multiple organic resin layers 24, it is possible to obtain a second insulating substrate 20 having therein second land conductors 42 (described later) and conductors with wiring shapes suitable for various purposes. Furthermore, by forming the multiple organic resin layers 24 into different shapes, the degree of freedom in designing the shape of the wiring substrate 100 can be improved. A wiring substrate 100 having such a second insulating substrate 20 has a high degree of freedom in designing the wiring and the shape of the wiring substrate 100. Note that the organic resin layer 24 refers to a layer containing an organic resin, and includes not only a layer composed only of an organic resin, but also a layer containing an organic resin and an inorganic material such as silica. Furthermore, the content of the organic resin in the organic resin layer 24 in terms of mass % may be smaller than the content of the inorganic material in the organic resin layer 24 in terms of mass %.

[0028] The second insulating substrate 20 is superimposed on the first surface 11 of the first insulating substrate 10. The third surface 21 of the second insulating substrate 20 is bonded to the first surface 11 of the first insulating substrate 10. That is, the second insulating substrate 20 is directly bonded to the first insulating substrate 10 without an adhesive layer. The adhesive layer here refers to a layer containing, for example, an epoxy resin, a polyimide resin, or a polyamide-imide resin, and refers to a layer in which a conductor for wiring, such as the first via conductor 31, is not explicitly formed. Specifically, the organic resin layer 24 of the second insulating substrate 20 may contain an epoxy-based resin. The ceramic layer 14 of the first insulating substrate 10 may contain a ceramic containing hydroxyl groups as a main component. In this case, the second insulating substrate 20 may be chemically bonded to the first insulating substrate 10 via the hydroxyl groups. This allows the first insulating substrate 10 and the second insulating substrate 20 to be hydrogen-bonded via the hydroxyl groups.

[0029] In this way, since there is no adhesive layer for joining the first insulating substrate 10 and the second insulating substrate 20, the thickness of the wiring substrate 100 is reduced, and the wiring substrate 100 can be made smaller.

[0030] In this embodiment, the second insulating substrate 20 has two organic resin layers 24, but the number of organic resin layers 24 is not limited to two. The number of organic resin layers 24 may be three or more. Furthermore, the second insulating substrate 20 does not necessarily have to have a multi-layer structure. In other words, the second insulating substrate 20 may be a single layer.

[0031] The second insulating substrate 20 containing an organic material is easier to form fine wiring patterns and narrow-pitch wiring patterns on than a substrate containing an inorganic material as a main component. On the other hand, the first insulating substrate 10 containing ceramic has higher rigidity than the second insulating substrate 20. The first insulating substrate 10 containing ceramic may also have a higher density than the second insulating substrate 20. When the second insulating substrate 20 is a single layer, the second insulating substrate 20 and the second land conductors 42 can be formed by additive manufacturing using a 3D printer.

[0032] The wiring board 100 can increase rigidity while achieving finer wiring and narrower pitches by combining the first insulating substrate 10 and the second insulating substrate 20. Since warping of the board becomes more pronounced as the board becomes larger, the configuration of the wiring board 100 in which the first insulating substrate 10 compensates for the low rigidity of the second insulating substrate 20 is particularly useful for increasing the size of the board.

[0033] The insulating substrate containing an organic material may be lighter than an insulating substrate containing a ceramic. In this case, the wiring board 100 according to the present disclosure, which includes the first insulating substrate 10 containing a ceramic and the second insulating substrate 20 containing an organic material, can be lighter than a wiring board formed only of an insulating substrate containing a ceramic.

[0034] <First Internal Conductor and Second Internal Conductor> Figure 4 is a cross-sectional view showing an example of the configuration of the first internal conductor, the second internal conductor, and the interlayer conductor. As shown in Figure 4, the first internal conductor 30 is located inside the first insulating substrate 10. The first internal conductor 30 may extend in a direction perpendicular to the first surface 11. Note that "extending" here does not necessarily mean extending over the shortest distance. Note that if the first insulating substrate 10 further includes a conductor located on the second surface 12, the first internal conductor 30 may be electrically connected to the conductor located on the second surface 12. Furthermore, a portion of the first internal conductor 30 may be exposed on the second surface 12 or the first side surface 13.

[0035] The first internal conductor 30 includes 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 may penetrate one or more ceramic layers 14. The first land conductor 32 may be located between the 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 location 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. For example, when the first insulating substrate 10 contains ceramic, holes are formed in a green sheet before sintering at positions that will become the first via conductors 31 by punching, laser processing, or the like, and the holes are filled with a conductive paste to form the first via conductors 31. At this time, some of the conductive paste filled in the holes may seep out onto the surface of the green sheet, forming a seeped portion. In this disclosure, however, such a seeped portion will not be treated as part of the via conductor, but will be treated as constituting part of the land conductor.

[0036] The first land conductor 32 may extend in one or more directions from the periphery of the first via conductor 31. In other words, the first land conductor 32 may have a first portion located around the first via conductor 31 and a second portion extending in one or more directions from the first portion. The first land conductor 32 may also have a so-called solid pattern. The first land conductor 32 may be in contact with other conductors on the same plane in the horizontal direction. In other words, the conductor area may extend in a partial direction of the first land conductor 32.

[0037] 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 organic resin substrates, the wiring board 100 has a high degree of freedom in designing the wiring because a material for the first internal conductor 30 can be selected that corresponds to the thermal expansion coefficient of the first insulating substrate 10. On the other hand, when a configuration is adopted in which wiring (the first internal conductor 30 and the second internal conductor 40) is provided on both the first insulating substrate 10 and the second insulating substrate 20, it is preferable to increase the bonding strength between the first insulating substrate 10 and the second insulating substrate 20 to reduce the possibility of misalignment between the first internal conductor 30 and the second internal conductor 40.

[0038] The second internal conductor 40 is located inside the second insulating substrate 20 and extends in a direction perpendicular to the first surface 11. Note that "extending" here does not necessarily mean extending over the shortest distance. For example, the second internal conductor 40 may have a second via conductor 41 (described later) inclined with respect to the direction perpendicular to the first surface 11. This point will be described later. Note that if the second insulating substrate 20 further includes a conductor located on the fourth surface 22, the second internal conductor 40 may be electrically connected to the conductor located on the fourth surface 22. Furthermore, a portion of the second internal conductor 40 may be exposed at the fourth surface 22 or the second side surface 23.

[0039] The second inner conductor 40 has a second via conductor 41 that penetrates at least a portion of the second insulating substrate 20, and a second land conductor 42 (see FIG. 2 ) that is electrically connected to the second via conductor 41. The second via conductor 41 penetrates one or more organic resin layers 24. The second land conductor 42 may be located between the multiple organic resin layers 24. The second land conductor 42 may be a portion that is located around the second via conductor 41 in a planar view. In other words, the second land conductor 42 may be located at a position that overlaps with the second via conductor 41 in a planar view.

[0040] The second land conductor 42 may extend in one or more directions from the periphery of the second via conductor 41. In other words, the second land conductor 42 may have a first portion located around the second via conductor 41 and a second portion extending in one or more directions from the first portion. The second land conductor 42 may also have a so-called solid pattern. The second land conductor 42 may be in contact with other conductors on the same plane in the horizontal direction. In other words, the conductor area may extend in a direction that is part of the second land conductor 42.

[0041] The first inner conductor 30 may be, for example, a metal conductor containing tungsten or molybdenum. As an example, the first via conductor 31 may be a metal conductor containing tungsten, and the first land conductor 32 may be a metal conductor containing molybdenum. Alternatively, the first via conductor 31 may be a metal conductor containing molybdenum, and the first land conductor 32 may be a metal conductor containing tungsten. Alternatively, both the first via conductor 31 and the first land conductor 32 may be metal conductors containing tungsten, or both the first via conductor 31 and the first land conductor 32 may be metal conductors containing molybdenum. Note that the first inner conductor 30 may be, for example, a metal conductor containing tungsten or molybdenum with copper or gold as the main component.

[0042] The second inner conductor 40 may be, for example, a metal conductor containing copper, or may be a metal conductor containing copper, tin, and bismuth.

[0043] More specifically, the weight percentage of copper contained in the second via conductor 41 may be 15% or more and 45% or less, and in this case, the weight percentage of tin contained in the second via conductor 41 may be 35% or more and 55% or less.

[0044] 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.

[0045] 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.

[0046] When the metal contained in the second via conductor 41 is copper, the surface of the copper may be coated. This configuration can reduce oxidation and deterioration of the copper. Examples of coating materials include silver.

[0047] 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.

[0048] The first internal conductor 30 may contain a glass material. In this case, the first internal conductor 30 is 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. This also allows the rigidity of the first insulating substrate 10 to be increased.

[0049] Furthermore, when the first internal conductor 30 contains a glass material, it is possible to adjust the shrinkage rates of the first insulating substrate 10 and the first internal conductor 30 in the firing process during the manufacturing of the wiring substrate 100. This makes it possible to make the firing temperatures of the first insulating substrate 10 and the first internal conductor 30 closer to each other. It is also possible to adjust the shrinkage rates of the first insulating substrate 10 and the first internal conductor 30.

[0050] <Physical Properties of First Insulating Substrate and Second Insulating Substrate> The thermal expansion coefficient of the first insulating substrate 10 may be smaller than the thermal expansion coefficient of the second insulating substrate 20. Because the second insulating substrate 20 is bonded to the first insulating substrate 10, with the above configuration, when the second insulating substrate 20 attempts to thermally deform due to a temperature change, the first insulating substrate 10 restrains the second insulating substrate 20, thereby reducing the thermal deformation of the second insulating substrate 20.

[0051] <Interlayer Conductor> As shown in Fig. 4 , 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 also to the second via conductor 41. The wiring board 100 having such an interlayer conductor 50 offers a high degree of design freedom. The interlayer conductor 50 may be a metal conductor containing tungsten or molybdenum. Alternatively, the interlayer conductor 50 may contain a glass material.

[0052] The interlayer conductor 50 is located at a position overlapping at least the first via conductor 31 and the second via conductor 41 in a plan view. As shown in Fig. 4, 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. In other words, the interlayer conductor 50 may have a structure having only a first portion located around the first via conductor 31 and the second via conductor 41, or may have a structure having the first portion and a second portion extending in one or more directions from the first portion. From another perspective, the interlayer conductor 50 may be in contact with another conductor on the same plane in the horizontal direction.

[0053] The interlayer conductor 50 has a first conductor layer 51 and a second conductor layer 52. The first conductor layer 51 is 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 second conductor layer 52 is located on the first conductor layer 51 and is electrically connected to the second internal conductor 40. Specifically, the second conductor layer 52 may be electrically connected to the second via conductor 41. The first conductor layer 51 contains a glass material. The second internal conductor 40 and the second conductor layer 52 contain the same metal material. The same metal material may be copper.

[0054] 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, are bonded together by melting the metal material through heat treatment during the manufacturing process. More specifically, an alloy may be formed at the bonded portion between the second internal conductor 40 and the second conductor layer 52. The alloy may be, for example, a copper-tin alloy mixed with bismuth. 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 may be 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, 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, the electrical connection between the first insulating substrate 10 and the second insulating substrate 20 is unlikely to be interrupted. Therefore, the wiring board 100 according to the present disclosure can improve the reliability of the electrical connection at the joint between the first insulating substrate 10 and the second insulating substrate 20.

[0055] The first conductor layer 51 may have a higher thermal conductivity than the first internal conductor 30. By increasing the thermal conductivity of the first conductor layer 51, which has a larger surface area than the first internal conductor 30, it is possible to release heat at the joint of the insulating substrate to the first insulating substrate 10 side. The metal material contained in the first conductor layer 51 may be tungsten, and the metal material contained in the first via conductor 31 may be molybdenum. The metal material contained in the first conductor layer 51 may be copper, and the metal material contained in the first via conductor 31 may be tungsten.

[0056] Furthermore, the metal material contained in the first conductor layer 51 may be the same as the metal material contained in the first internal conductor 30. This strengthens the bond between the first conductor layer 51 and the first internal conductor 30. Furthermore, the same metal material has the same ionization tendency, melting point, or specific gravity, which reduces the possibility of metal diffusion between the first conductor layer 51 and the first internal conductor 30 and chemical reactions such as corrosion due to metal diffusion.

[0057] Furthermore, when the metal material contained in the first conductor layer 51 is the first metal material and the metal material contained in the second internal conductor 40 and the second conductor layer 52 is the second metal material, the thermal conductivity of the second metal material may be higher than that of the first metal material. In this case, the first conductor layer 51, the second internal conductor 40, and the second conductor layer 52 have a higher thermal conductivity than the first insulating substrate 10 and the second insulating substrate 20. This prevents heat from being trapped in the second insulating substrate 20 and allows heat to dissipate to the first insulating substrate 10, which has a higher thermal conductivity. Furthermore, when a heat source is present on the first insulating substrate 10 side, heat can be guided to the second internal conductor 40 and the second conductor layer 52 rather than the second insulating substrate 20. The first metal material may be tungsten or molybdenum. The second metal material may be copper.

[0058] The glass material content of the second conductor layer 52 may be lower than that of the first conductor layer 51. The glass material content of the second internal conductor 40 may be lower than that of the first internal conductor 30. For example, the glass material content of the second conductor layer 52 and the glass material content of the second internal conductor 40 may be zero. As a result, the second conductor layer 52 and the second internal conductor 40 have a low content of glass material, which is a component other than metal, i.e., a high content of metal. Therefore, this configuration can improve the thermal conductivity of the second conductor layer 52 and the second internal conductor 40.

[0059] Furthermore, the thickness of the first conductor layer 51 may be greater than the thickness of the second conductor layer 52. This allows the second conductor layer 52 to function even when it is thin, and therefore, by making the second conductor layer 52 thinner, the manufacturing cost can be reduced.

[0060] The second conductor layer 52 may also be a plated layer. This allows the second conductor layer 52 to be thinner, thereby reducing manufacturing costs. Furthermore, the second conductor layer 52 can be positioned on the first conductor layer 51 by immersing the metal of the first conductor layer 51 in a solution containing the metal ions that constitute the second conductor layer 52. Therefore, when the second conductor layer 52 is a plated layer, the possibility of the second conductor layer 52 being formed in an unwanted position or of the second conductor layer 52 and the first conductor layer 51 being misaligned can be reduced compared to when the second conductor layer 52 is a layer formed by screen printing.

[0061] The interlayer conductor 50 may further include an intermediate conductor layer 53 located between the first conductor layer 51 and the second conductor layer 52. This prevents unintended chemical reactions between the first conductor layer 51 and the second conductor layer 52. The intermediate conductor layer 53 also functions as a barrier layer, reducing the possibility of cracks occurring in the interlayer conductor 50 due to a reaction between the first conductor layer 51 and the second conductor layer 52, reducing durability against external impacts. Furthermore, the interlayer conductor 50 may be less likely to have copper contained in the second conductor layer 52 penetrate into the grain boundaries of the first conductor layer 51.

[0062] Furthermore, the intermediate conductor layer 53 may be a plated layer. This allows the intermediate conductor layer 53 to be made thinner, thereby reducing the thickness of the interlayer conductor 50. This reduces the possibility that the second insulating substrate 20 will bulge above the interlayer conductor 50 when joining the second insulating substrate 20 and the first insulating substrate 10. Furthermore, the intermediate conductor layer 53 can be positioned on the first conductor layer 51 by immersing the metal of the first conductor layer 51 in a solution containing the metal ions that constitute the intermediate conductor layer 53. Therefore, when the intermediate conductor layer 53 is a plated layer, it is less likely that the intermediate conductor layer 53 will be formed in an unwanted position or that the intermediate conductor layer 53 and the first conductor layer 51 will be misaligned, compared to when the intermediate conductor layer 53 is a layer formed by screen printing.

[0063] Furthermore, when the metal material contained in the first conductor layer 51 is the first metal material, the metal material contained in the second conductor layer 52 is the second metal material, and the metal material contained in the intermediate conductor layer 53 is the third metal material, the linear thermal expansion coefficient α3 of the third metal material may be between the linear thermal expansion coefficient α1 of the first metal material and the linear thermal expansion coefficient α2 of the second metal material. In other words, the linear thermal expansion coefficient α3 of the third metal material may be greater than the linear thermal expansion coefficient α1 of the first metal material and less than the linear thermal expansion coefficient α2 of the second metal material.

[0064] This allows the third metal material to be positioned between the first metal material and the second metal material, reducing the possibility of the first metal material and the second metal material peeling off due to the difference in linear thermal expansion coefficients caused by repeated thermal expansion and contraction during mounting of the electronic component or operation of the electronic component. The linear thermal expansion coefficient α3 of the third metal material may be smaller than the linear thermal expansion coefficient α1 of the first metal material and larger than the linear thermal expansion coefficient α2 of the second metal material. The first metal material may be tungsten or molybdenum. The second metal material may be copper. The third metal material may be nickel.

[0065] Furthermore, the linear thermal expansion coefficient α1 of the first metal material may be smaller than the linear thermal expansion coefficient α2 of the second metal material. Thus, when the first insulating substrate 10 is a ceramic substrate, by reducing the linear thermal expansion coefficient of the first metal material located on the ceramic substrate side, it is possible to reduce the possibility of cracks occurring in the ceramic substrate due to thermal expansion of the first conductor layer 51 caused by repeated thermal expansion and contraction during mounting and operation of electronic components.

[0066] 4 , in a cross-sectional view, at least one of the interlayer conductor 50 and the first land conductor 32 may become thinner with increasing distance from the first via conductor 31. Meanwhile, in a cross-sectional view, the second land conductor 42 may be trapezoidal. More specifically, the width of the second land conductor 42 may become smaller 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 contact between the second land conductor 42 and the second via conductor 41 can be more reliably achieved.

[0067] <Semiconductor Device> Fig. 5 is a perspective view showing an example of the configuration of a semiconductor device according to an embodiment. Fig. 6 is a cross-sectional perspective view showing an example of the configuration of a semiconductor device according to an embodiment. As shown in Figs. 5 and 6, a semiconductor device 300 includes a wiring substrate 100, a semiconductor element 310, and an optical filter 320.

[0068] The semiconductor element 310 is mounted on the wiring board 100. In the example shown in Figures 5 and 6, 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 110. In the example shown in Figures 5 and 6, 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 is located so as to face the open end of the through hole 110 on the fourth surface 22.

[0069] The semiconductor element 310 is, for example, an image sensor, and generates heat due to the operation of the image sensor. When thermal expansion and thermal contraction are repeated due to the operation of the image sensor, the wiring substrate 100 can reduce the possibility that the electrical connection between the insulating substrates will be broken due to the difference in thermal expansion coefficient between the first insulating substrate 10 and the second insulating substrate 20. The semiconductor element 310 may be electrically connected to the wiring substrate 100 by solder, i.e., flip-chip mounting, or by bonding wire.

[0070] 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.

[0071] The present disclosure has been described in detail above, but the present disclosure is not limited to the above-described embodiments, and various modifications, improvements, etc. are possible within the scope that does not deviate from the gist of the present disclosure.

[0072] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. Indeed, the above-described embodiments can be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims. Combinations of embodiments are also possible.

[0073] The present technology can also be configured as follows. (1) A wiring board comprising: a first insulating substrate having a first surface and containing a glass material; a second insulating substrate partially in contact with the first surface and containing a resin material; a first internal conductor located within 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 within 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. (2) The wiring board according to (1), wherein the first internal conductor contains a glass material. (3) The wiring board according to (1) or (2), wherein the first conductor layer has a higher thermal conductivity than the first internal conductor. (4) The wiring board according to any one of (1) to (3), wherein the metal material contained in the first conductor layer is the same as the metal material contained in the first internal conductor. (5) The wiring board according to any one of (1) to (4), wherein, when the metal material contained in the first conductor layer is a first metal material, and the metal materials contained in the second internal conductor and the second conductor layer are a second metal material, the thermal conductivity of the second metal material is higher than the thermal conductivity of the first metal material. (6) The wiring board according to any one of (1) to (5), wherein the glass material content of the second conductor layer is lower than the glass material content of the first conductor layer, and the glass material content of the second internal conductor is lower than the glass material content of the first internal conductor. (7) The wiring board according to any one of (1) to (6), wherein the thickness of the first conductor layer is greater than the thickness of the second conductor layer. (8) The wiring board according to any one of (1) to (6), wherein the second conductor layer is a plating layer. (9) The wiring board according to (1), further comprising an intermediate conductor layer located between the first conductor layer and the second conductor layer. (10) The wiring board according to (9), wherein the intermediate conductor layer is a plating layer.(11) The wiring board according to (9) or (10), wherein, when the metal material contained in the first conductor layer is a first metal material, the metal material contained in the second conductor layer is a second metal material, and the metal material contained in the intermediate conductor layer is a third metal material, the linear thermal expansion coefficient of the third metal material is between the linear thermal expansion coefficients of the first metal material and the second metal material. (12) The wiring board according to (11), wherein the linear thermal expansion coefficient of the first metal material is smaller than the linear thermal expansion coefficient of the second metal material. (13) A semiconductor device comprising: the wiring board according to any one of (1) to (12); and a semiconductor element mounted on the wiring board, wherein the semiconductor element generates heat when in operation.

[0074] REFERENCE SIGNS LIST 10 First insulating substrate 11 First surface 20 Second insulating substrate 30 First internal conductor 40 Second internal conductor 51 First conductor layer 52 Second conductor layer 53 Intermediate conductor layer 100 Wiring substrate 300 Semiconductor device 310 Semiconductor element

Claims

1. A wiring board comprising: a first insulating substrate having a first surface and containing a glass material; a second insulating substrate partially in contact with the first surface and containing a resin material; a first internal conductor located within 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 within the second insulating substrate and electrically connected to the second conductor layer, wherein the thermal conductivity of the first insulating substrate is higher than that 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.

2. The wiring board according to claim 1, wherein the first internal conductor contains a glass material.

3. The wiring board according to claim 1 or 2, wherein the thermal conductivity of the first conductor layer is higher than that of the first internal conductor.

4. The wiring board according to any one of claims 1 to 3, wherein the metal material contained in the first conductor layer is the same as the metal material contained in the first internal conductor.

5. The wiring board according to any one of claims 1 to 4, wherein when the metal material contained in the first conductor layer is defined as a first metal material and the metal material contained in the second internal conductor and the second conductor layer is defined as a second metal material, the thermal conductivity of the second metal material is higher than that of the first metal material.

6. The wiring board according to any one of claims 1 to 5, wherein the content rate of the glass material in the second conductor layer is lower than that in the first conductor layer, and the content rate of the glass material in the second internal conductor is lower than that in the first internal conductor.

7. The wiring board according to any one of claims 1 to 6, wherein the thickness of the first conductor layer is larger than that of the second conductor layer.

8. The wiring board according to any one of claims 1 to 6, wherein the second conductor layer is a plating layer.

9. The wiring board according to claim 1, further comprising an intermediate conductor layer located between the first conductor layer and the second conductor layer.

10. The wiring board according to claim 9, wherein the intermediate conductor layer is a plating layer.

11. When the metal material contained in the first conductor layer is defined as the first metal material, the metal material contained in the second conductor layer is defined as the second metal material, and the metal material contained in the intermediate conductor layer is defined as the third metal material, the linear thermal expansion coefficient of the third metal material is between the linear thermal expansion coefficient of the first metal material and the linear thermal expansion coefficient of the second metal material. The wiring substrate according to claim 9 or claim 10.

12. The linear thermal expansion coefficient of the first metal material is smaller than the linear thermal expansion coefficient of the second metal material. The wiring substrate according to claim 11.

13. A semiconductor device comprising the wiring substrate according to any one of claims 1 to 12 and a semiconductor element mounted on the wiring substrate, wherein the semiconductor element generates heat during operation.

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