Wiring board

Abstract

According to the present invention, a first base material has a first surface and a second surface positioned on the opposite side to the first surface. A second base material has a third surface and a fourth surface positioned on the opposite side to the third surface. First wiring is located inside the first base material and extends from the first surface toward the second surface. Second wiring is located inside the second base material and extends from the third surface toward the fourth surface. The first base material has a plurality of ceramic layers including a first surface layer having a first surface and a second surface layer having a second surface. The second base material has a plurality of organic resin layers including a third surface layer having a third surface. The third surface of the second base material is joined to the first surface of the first base material. The first wiring has a first via conductor passing through the first surface layer. The second wiring has a third via conductor passing through the third surface layer. The inclination angle of the first via conductor with respect to the thickness direction of the first base material is greater than the inclination angle of the third via conductor with respect to the thickness direction of the first base material.

Description

wiring board

[0001] The present disclosure relates to a wiring substrate.

[0002] Conventionally, wiring boards in which two types of substrates made of different materials are bonded together have been known. For example, Patent Document 1 discloses a wiring board in which an organic substrate on which wiring is formed is bonded to a glass cloth substrate as a core material. A through-hole portion is formed in the glass cloth substrate. The through-hole portion includes a through-hole penetrating the glass cloth substrate, a plating film covering the inner wall of the through-hole, and a resin filled inside the through-hole.

[0003] JP 2023-111608 A

[0004] A wiring board according to one embodiment of the present disclosure includes a first substrate, a second substrate, a first wiring, and a second wiring. The first substrate has a first surface and a second surface opposite the first surface. The second substrate has a third surface and a fourth surface opposite the third surface. The first wiring is located inside the first substrate and extends from the first surface toward the second surface. The second wiring is located inside the second substrate and extends from the third surface toward the fourth surface. The first substrate has multiple ceramic layers including a first surface layer having a first surface and a second surface layer having a second surface. The second substrate has multiple organic resin layers including a third surface layer having a third surface. The third surface of the second substrate is bonded to the first surface of the first substrate. The first wiring has a first via conductor penetrating the first surface layer. The second wiring has a third via conductor penetrating the third surface layer. The inclination angle of the first via conductor relative to the thickness direction of the first base material is larger than the inclination angle of the third via conductor relative to the thickness direction of the first base material.

[0005] FIG. 1 is a cross-sectional view showing an example of the configuration of a semiconductor device according to a first embodiment. FIG. 2 is a schematic plan view of a semiconductor device according to an embodiment. FIG. 3 is a schematic cross-sectional view showing an enlarged portion of a wiring board according to an embodiment. FIG. 4 is a schematic plan perspective view showing an example of the configuration of a first base material according to an embodiment. FIG. 5 is a schematic cross-sectional view showing an enlarged portion of a wiring board according to an embodiment. FIG. 6 is an enlarged cross-sectional view showing an example of the configuration of part H1 shown in FIG. 3. FIG. 7 is an enlarged cross-sectional view showing an example of the configuration of part H2 shown in FIG. 6. FIG. 8 is a cross-sectional view showing an example of the configuration of a wiring board according to a second embodiment.

[0006] Hereinafter, a detailed description will be given of a form for carrying out a wiring board according to the present disclosure (hereinafter referred to as an "embodiment") with reference to the drawings. Note that the present disclosure is not limited to the embodiment. Furthermore, each embodiment can be appropriately combined as long as there is no contradiction in the processing content. Furthermore, the same components in each of the following embodiments are given the same reference numerals, and duplicated explanations will be omitted.

[0007] Furthermore, in the embodiments described below, expressions such as "orthogonal" or "vertical" may be used, but these expressions do not necessarily mean "orthogonal" or "vertical" in the strict sense. In other words, the expressions described above allow for deviations due to, for example, manufacturing precision, installation precision, etc.

[0008] In addition, in the following embodiments, expressions such as "parallel" may be used, but these expressions do not necessarily mean "parallel" in the strict sense. In other words, the above expressions allow for deviations due to, for example, manufacturing precision, installation precision, etc.

[0009] 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.

[0010] The above-described conventional techniques have room for improvement in terms of improving the bonding reliability of two types of substrates made of different materials. The present disclosure provides a technique that can improve the bonding reliability.

[0011] <First Embodiment> Fig. 1 is a cross-sectional view showing an example of the configuration of a semiconductor device according to the first embodiment. As shown in Fig. 1, a semiconductor device 100 according to the first embodiment includes a wiring substrate 1, a semiconductor element 2, and a motherboard 3. The wiring substrate 1 includes a first substrate 10 and a second substrate 20. The wiring substrate 1 is a laminate of the first substrate 10 and the second substrate 20. The wiring substrate 1 also includes a first wiring 30 and a second wiring 40.

[0012] <First Substrate> The first substrate 10 may be formed using a ceramic composite material containing a glass component, so-called glass ceramic. The glass ceramic may be any of a composite of a glass phase and ceramic particles, a composite of a glass phase and a crystalline phase formed by crystallization of a portion of the glass phase, a composite in which ceramic particles exist in a glass phase, and a composite in which a glass phase exists at the grain boundaries between ceramic particles.

[0013] For example, the first substrate 10 may be made of low temperature co-fired ceramics (LTCC). When LTCC is used as the first substrate 10, a low-melting-point metal such as copper or silver, which has a relatively low electrical resistance, can be used as wiring.

[0014] The first substrate 10 may contain ceramic fillers as ceramic particles. Ceramic fillers are additives that help improve the thermal conductivity of ceramics. Examples of ceramic fillers that can be used include alumina (aluminum oxide), calcium titanate, and magnesium titanate. In particular, the first substrate 10 containing alumina has high rigidity.

[0015] The first substrate 10 has a first surface 101 and a second surface 102 located on the opposite side to the first surface 101. The first substrate 10 may be a plate-like body having the first surface 101 and the second surface 102 as main surfaces.

[0016] In the first embodiment, the first substrate 10 has a plurality of ceramic layers 11. The plurality of ceramic layers 11 are stacked along the thickness direction of the first substrate 10 (here, the Z-axis direction). By constructing the first substrate 10 using a plurality of ceramic layers 11 in this manner, it is possible to obtain a first substrate 10 having a wiring layer 32 therein. In other words, a wiring board 1 having such a first substrate 10 has a high degree of design freedom. Furthermore, by constructing the first substrate 10 using a plurality of ceramic layers 11, it is possible to manufacture the first substrate 10 while checking whether the first wiring 30 is properly formed for each layer, thereby improving the yield of the first substrate 10.

[0017] The plurality of ceramic layers 11 include a first surface layer 111, a second surface layer 112, and an inner layer 113. The first surface layer 111 is a ceramic layer having a first surface 101. In other words, the first surface layer 111 is a ceramic layer among the plurality of ceramic layers 11 that is bonded to the second substrate 20. The second surface layer 112 is a ceramic layer having a second surface 102. In other words, the second surface layer 112 is a ceramic layer located opposite the first surface layer 111 with the inner layer 113 interposed therebetween. The inner layer 113 is a ceramic layer located between the first surface layer 111 and the second surface layer 112.

[0018] Although an example in which ceramic layer 11 includes one inner layer 113 is shown here, ceramic layer 11 may include multiple inner layers 113. Furthermore, ceramic layer 11 does not necessarily have to include inner layer 113. In other words, ceramic layer 11 may have a configuration including only first surface layer 111 and second surface layer 112.

[0019] The first surface 101 of the first substrate 10 is bonded to the third surface 103 of the second substrate 20. The second surface 102 of the first substrate 10 is connected to the top of the motherboard 3 via the bonding portion 4.

[0020] <Second Base Material> The second base material 20 is a base material mainly composed of an organic component. The organic component 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, or a polyphenylene resin.

[0021] The organic resin may be, for example, polytetrafluoroethylene (PTFE) or other fluororesin or polyphenylene ether resin. The second substrate 20 may contain components other than the organic resin. In this disclosure, a "major component" refers to a material that accounts for, for example, 50% by mass or more of the material.

[0022] The second substrate 20 has a third surface 103 and a fourth surface 104 located on the opposite side to the third surface 103. The second substrate 20 may be a plate-like body having the third surface 103 and the fourth surface 104 as main surfaces.

[0023] The second base material 20 has a plurality of organic resin layers 12. The plurality of organic resin layers 12 are stacked along the thickness direction (here, the Z-axis direction) of the second base material 20. By configuring the second base material 20 using the plurality of organic resin layers 12, it is possible to obtain a second base material 20 having a wiring layer 42 therein.

[0024] The plurality of organic resin layers 12 include a third surface layer 121 and a fourth surface layer 122. Third surface layer 121 is an organic resin layer 12 having a third surface 103. In other words, third surface layer 121 is an organic resin layer 12 bonded to first substrate 10. Fourth surface layer 122 is an organic resin layer 12 having a fourth surface 104.

[0025] The third surface 103 of the second substrate 20 is bonded to the first surface 101 of the first substrate 10. A semiconductor element 2 is mounted on the fourth surface 104 of the second substrate 20. The semiconductor element 2 is, for example, a semiconductor chip. The semiconductor element 2 may be a chip or chiplet in which circuits and elements are formed on a substrate made of a material other than a semiconductor, such as a glass substrate. The semiconductor device 100 may include two or more semiconductor elements 2.

[0026] The second base material 20 has a plurality of organic resin layers 12. The plurality of organic resin layers 12 are stacked along the thickness direction of the second base material 20 (here, the Z-axis direction). By configuring the second base material 20 using a plurality of organic resin layers 12, it is possible to obtain a second base material 20 having a wiring layer 42 therein. A wiring board 1 having such a second base material 20 has a high degree of freedom in design.

[0027] 1, the second base material 20 has two organic resin layers 12, but the number of organic resin layers 12 is not limited to two. The number of organic resin layers 12 may be one, or three or more.

[0028] 1, the second substrate 20 is bonded to one main surface (here, the first surface 101) of the first substrate 10, but the wiring board 1 may be configured such that the second substrate 20 is provided on both main surfaces (the first surface 101 and the second surface 102) of the first substrate 10. An example of this configuration will be described later.

[0029] The second substrate 20, which is primarily composed of an organic component, is easier to form a fine wiring pattern on than an inorganic substrate. On the other hand, the first substrate 10, which is made of ceramic, is more rigid than the second substrate 20. Furthermore, the second substrate 20, which is primarily composed of an organic component, has a lower density than the first substrate 10.

[0030] The wiring board 1 according to the first embodiment can increase rigidity while achieving finer wiring and narrower pitches by combining the first substrate 10 and the second substrate 20. Since warping of the board becomes more pronounced as the board becomes larger, the configuration of the wiring board 1 in which the first substrate 10 compensates for the low rigidity of the second substrate 20 is particularly useful for increasing the size of the board.

[0031] Furthermore, since the wiring board 1 according to the first embodiment includes the second base material 20 that has a lower density than the inorganic substrate, it can be made lighter than a wiring board made of only an inorganic substrate.

[0032] <First Wiring and Second Wiring> The first wiring 30 is located inside the first base material 10, and extends from one of the first surface 101 and the second surface 102 to the other. Note that "extending" here does not necessarily mean extending the shortest distance.

[0033] The first wiring 30 may include a plurality of via conductors 31 and one or a plurality of wiring layers 32. The via conductors 31 penetrate at least one of the plurality of ceramic layers 11. The wiring layers 32 are located between adjacent ceramic layers 11 and electrically connect the plurality of via conductors 31 together.

[0034] In this way, the wiring board 1 has the first wiring 30 including the multiple wiring layers 32 inside the first base material 10, and therefore has a higher degree of freedom in wiring design compared to conventional wiring boards that have wiring only on an organic resin substrate. On the other hand, when a configuration is adopted in which wiring is provided on both the first base material 10 and the second base material 20, in this case the first wiring 30 and the second wiring 40, it is desirable to bond the first base material 10 and the second base material 20 more firmly so that misalignment between the first wiring 30 and the second wiring 40 does not occur.

[0035] 1 shows an example in which the first wiring 30 has the wiring layer 32, but the first wiring 30 does not necessarily have to have the wiring layer 32. Furthermore, the first wiring 30 may have a wiring layer located on the surface of the first base material 10, specifically, on the first surface 101 or the second surface 102.

[0036] The second wiring 40 is located inside the second base material 20 and extends from one of the third surface 103 and the fourth surface 104 to the other. Note that "extending" here does not necessarily mean extending the shortest distance. The second wiring 40 may be electrically connected to the first wiring 30 at the joint surface between the first base material 10 and the second base material 20.

[0037] The second wiring 40 has a plurality of via conductors 41 and one or more wiring layers 42. The via conductors 41 penetrate one or more organic resin layers 12. The wiring layers 42 are located between adjacent organic resin layers 12 and electrically connect the plurality of via conductors 41 to each other.

[0038] 1 shows an example in which the second wiring 40 has the wiring layer 42, but the second wiring 40 does not necessarily have to have the wiring layer 42. In addition, the second wiring 40 may have a wiring layer located on the surface (third surface 103 or fourth surface 104) of the second base material 20.

[0039] The first wiring 30 and the second wiring 40 may be, for example, a metal conductor whose main component is copper or silver. For example, both the first wiring 30 and the second wiring 40 may be a metal conductor whose main component is copper. Alternatively, both the first wiring 30 and the second wiring 40 may be a metal conductor whose main component is silver. Alternatively, one of the first wiring 30 and the second wiring 40 may be a metal conductor whose main component is copper, and the other may be a metal conductor whose main component is silver.

[0040] By making all of the first wiring 30 and the second wiring 40 metal conductors whose main component is copper or silver, it is possible to obtain higher electrical characteristics compared to, for example, when one of the first wiring 30 and the second wiring 40 is made of a metal conductor other than copper or silver.

[0041] The thermal expansion coefficient of the resin is higher than that of the glass cloth substrate, and the difference is relatively large. Therefore, in the technology described in Patent Document 1, when the temperature of the wiring substrate increases, the resin expands thermally and escapes from the through-holes. This may push up the wiring on the organic substrate, making the organic substrate more likely to peel off from the glass cloth substrate. Furthermore, there is a risk that electrical conduction between the wiring on the organic substrate and the plating film may become insufficient.

[0042] In contrast, in the wiring board 1 according to the embodiment, the interior of the through hole formed in the first base material 10 is filled with a via conductor 31 primarily made of metal. The via conductor 31 primarily made of metal has a lower thermal expansion coefficient than the resin filler. Furthermore, the difference in thermal expansion coefficient between the ceramic first base material 10 and the via conductor 31 primarily made of metal is smaller than the difference in thermal expansion coefficient between the glass cloth substrate and the resin filler.

[0043] Therefore, even if the via conductors 31 thermally expand, the via conductors 31 are less likely to push up against the second substrate 20 compared to the wiring board described in Patent Document 1, which makes it less likely that the second substrate 20 will peel off and also less likely that electrical continuity will be interrupted between the second wiring 40 and the first wiring 30. Therefore, the wiring board 1 according to the embodiment has high bonding reliability between the first substrate 10 and the second substrate 20.

[0044] Of the first wiring 30 and the second wiring 40, only the first wiring 30 may contain a silica component. In such a configuration, the first wiring 30 is bonded to the first substrate 10, which also contains a silica component, via the silica component. Specifically, the silica component contained in the first wiring 30 is integrated with the glass component contained in the first substrate 10 by firing. When the silica component contained in the first wiring 30 and the glass component contained in the first substrate 10 are integrated, an anchor effect due to the silica component occurs between the first substrate 10 and the first wiring 30, strengthening the bond between the first substrate 10 and the first wiring 30. This increases the rigidity of the first substrate 10.

[0045] Furthermore, in the firing step when manufacturing the wiring board 1, the shrinkage rates of the first base material 10 and the first wiring 30 can be made to be equal to some extent, so that the first wiring 30 is less likely to be misaligned.

[0046] The first wiring 30 may be formed, for example, by printing a conductive paste containing copper and glass components on a green sheet that is the raw material of the ceramic layer 11, and firing the green sheet simultaneously with the green sheet. Specifically, the conductive paste may contain, for example, copper powder, borosilicate glass powder, and silica particles.

[0047] On the other hand, the second wiring 40 may be formed by copper plating, whereby, of the first wiring 30 and the second wiring 40, only the first wiring 30 can be configured to contain a silica component.

[0048] The second wiring 40 may be electrically and thermally connected to the semiconductor element 2 placed on the fourth surface 104 of the second base material 20. By thermally connecting the second wiring 40, which is mainly composed of copper or silver, which has a relatively high thermal conductivity, to the semiconductor element 2, which serves as a heat source, the heat generated from the semiconductor element 2 can be efficiently dissipated via the second wiring 40 and the first wiring 30.

[0049] <Regarding the Inclination of the Via Conductor of the First Wiring> Next, a specific configuration of the via conductor 31 of the first wiring 30 will be described with reference to FIGS. 2 and 3. FIG. 2 is a schematic plan view of a semiconductor device 100 according to an embodiment. FIG. 3 is a schematic cross-sectional view showing an enlarged portion of the wiring substrate 1 according to an embodiment. Note that FIG. 1 shows a cross-sectional view taken along the arrow II shown in FIG. 2, and FIG. 3 shows an enlarged view of the cross-sectional view shown in FIG. 1. Specifically, FIGS. 1 and 3 show an example of a cross-sectional view of the semiconductor device 100 cut along a plane that is parallel to the stacking direction (here, the Z-axis direction) of the plurality of ceramic layers 11 and passes through the center of the first substrate 10.

[0050] As shown in Figure 3, of the multiple via conductors 31 that the first wiring 30 has, the via conductor that penetrates the first surface layer 111 is referred to as the "first via conductor 311," and of the multiple via conductors 41 that the second wiring 40 has, the via conductor that penetrates the third surface layer 121 is referred to as the "third via conductor 411."

[0051] In the wiring board 1 according to the embodiment, the first via conductors 311 are inclined with respect to the thickness direction of the first base material 10, in other words, with respect to the stacking direction of the plurality of ceramic layers 11. Specifically, the inclination angle of the first via conductors 311 with respect to the thickness direction of the first base material 10 is larger than the inclination angle of the third via conductors 411 with respect to the thickness direction of the first base material 10.

[0052] When the temperature of the wiring board increases, the via conductors 31 thermally expand, and the thermally expanded via conductors 31 push up the second substrate 20, which may cause the second substrate 20 to easily peel off from the first substrate 10. Furthermore, when the thermally expanded via conductors 31 push up the second substrate 20, there is a risk that electrical conduction between the first wiring 30 located on the first substrate 10 and the second wiring 40 located on the second substrate 20 may become insufficient.

[0053] In contrast, in the wiring board 1 according to the embodiment, the first via conductors 311 located on the first surface layer 111 of the first substrate 10 are inclined with respect to the thickness direction of the first substrate 10. When thermally expanded, the first via conductors 311 extend not only in the thickness direction of the first substrate 10 but also in an in-plane direction perpendicular to the thickness direction. Therefore, the first via conductors 311 according to the embodiment extend less in the thickness direction of the first substrate 10 when thermally expanded than via conductors that extend straight toward the second substrate 20. In other words, the first via conductors 311 according to the embodiment are less likely to push up against the second substrate 20 when thermally expanded than via conductors that extend straight toward the second substrate 20.

[0054] Therefore, in the wiring board 1 according to the embodiment, even if the first via conductors 311 thermally expand, the second base material 20 is unlikely to peel off from the first base material 10. Furthermore, electrical conduction between the first wiring 30 located on the first base material 10 and the second wiring 40 located on the second base material 20 is unlikely to become insufficient.

[0055] Thus, according to the wiring board 1 of the embodiment, even if the first via conductor 311 thermally expands, the dimensional change of the first via conductor 311 is unlikely to affect the second substrate 20, thereby providing high bonding reliability between the first substrate 10 and the second substrate 20.

[0056] First surface layer 111 has fifth surface 105 located opposite first surface 101. First via conductor 311 may have first end 311a located on first surface 101 and second end 311b located on fifth surface 105.

[0057] When the distance from a line P that passes through the center of the first substrate 10 and is parallel to the thickness direction of the first substrate 10 to the first end 311a is L1 and the distance from the line P to the second end 311b is L2, the first via conductor 311 may be inclined so that L1 > L2. In other words, the first via conductor 311 may be inclined so that the first end 311a, which is the end on the second substrate 20 side, is located closer to the outer periphery of the first substrate 10 than the second end 311b, which is the other end.

[0058] This allows the first wiring 30 and the second wiring 40 to be connected closer to the outer periphery of the second base material 20, thereby increasing the wiring density of the second base material 20.

[0059] 3. That is, the first via conductor 311 may be inclined so that L1 < L2. In other words, the first via conductor 311 may be inclined so that the first end 311a, which is the end on the second substrate 20 side, is located closer to the center of the first substrate 10 than the second end 311b, which is the other end.

[0060] Furthermore, when the first substrate 10 is viewed in cross section, some of the multiple first via conductors 311 may be located on one outer periphery of the first surface layer 111, and other parts may be located on the other outer periphery of the first surface layer 111.

[0061] 3 illustrates first via conductors 311 located on the outer periphery of first surface layer 111 on the negative X-axis direction side, and first via conductors 311 located on the outer periphery of first surface layer 111 on the positive X-axis direction side. Similarly, first via conductors 311 located on the outer periphery of first surface layer 111 on the positive X-axis direction side may also be inclined so that L1 < L2.

[0062] When thermally expanded, the inclined first via conductors 311 apply force to the second substrate 20 not only in the thickness direction but also in the in-plane direction. When the inclined first via conductors 311 are configured to be located on both outer peripheries of the first surface layer 111, as in the wiring board 1 according to the embodiment, the force acting in the in-plane direction by one of the first via conductors 311 on the second substrate 20 can be reduced by the force acting in the in-plane direction by the other first via conductor 311 on the second substrate 20. This makes it less likely that misalignment will occur in the in-plane direction between the first substrate 10 and the second substrate 20, compared to, for example, when the first via conductors 311 are located only on one end of the first surface layer 111.

[0063] Thus, according to the wiring board 1 according to the embodiment, even when the first via conductors 311 are inclined, the first base material 10 and the second base material 20 are less likely to be misaligned in the in-plane direction.

[0064] As an example, when the first substrate 10 is viewed in cross section, the outer peripheral portion of the first surface layer 111 may be a region including the outer edge of the first substrate 10 among a plurality of regions obtained by dividing the first substrate 10 into ten equal parts in the surface direction. In this case, when the first substrate 10 is viewed in cross section, some of the plurality of first via conductors 311 may be located in one of the regions including the outer edge of the first substrate 10 among a plurality of regions obtained by dividing the first substrate 10 into ten equal parts in the surface direction. Furthermore, another portion of the plurality of first via conductors 311 may be located in the other region including the outer edge of the first substrate 10 among a plurality of regions obtained by dividing the first substrate 10 into ten equal parts in the surface direction.

[0065] 3 , the inclination angle of first via conductors 311 located in the central portion of first surface layer 111 may be smaller than the inclination angle of first via conductors 311 located in the outer periphery of first surface layer 111. In other words, multiple first via conductors 311 may be arranged such that the inclination angle increases from the central portion of first surface layer 111 toward the outer periphery of first surface layer 111.

[0066] The bonding strength between the first substrate 10 and the second substrate 20 is likely to be weaker at the outer periphery of the first substrate than at the center of the first substrate 10. According to the wiring board 1 according to the embodiment, good electrical conduction is ensured by relatively increasing the straightness of the first via conductors 311 located at the center of the first substrate 10, while the straightness of the first via conductors 311 located at the outer periphery is relatively decreased, thereby making the bonding strength between the first substrate 10 and the second substrate 20 relatively weak. In other words, it is possible to make it less likely that a force that pushes up the second wiring 40 will be generated in the outer periphery where peeling of the second wiring 40 is likely to occur.

[0067] Furthermore, the decrease in bonding strength between the first substrate 10 and the second substrate 20 at the outer periphery becomes more pronounced as the size of the wiring board 1 increases. According to the wiring board 1 according to the embodiment having the above effects, the second wiring 40 is less likely to be pushed up at the outer periphery, and therefore the wiring board 1 can be easily increased in size compared to conventional wiring boards.

[0068] 3 , the first wiring 30 may have a “first wiring layer 321” located on the outer periphery in the in-plane direction of the first base material 10, and a “second wiring layer 322” located closer to the center in the plane of the first base material 10 than the first wiring layer 321. In this case, the thickness of the first wiring layer 321 may be greater than the thickness of the second wiring layer 322.

[0069] Next, the inclination direction of the via conductors 31 of the first wiring 30 will be described in more detail with reference to Fig. 4. Fig. 4 is a schematic planar perspective view showing an example of the configuration of the first substrate 10 according to the embodiment. Specifically, Fig. 4 is a planar perspective view of the first surface 101 of the first substrate 10 viewed from a direction perpendicular to the first surface 101. Fig. 4 illustrates only the first via conductors 311 located at the outermost periphery of the first surface layer 111, out of the multiple first via conductors 311 penetrating the first surface layer 111 of the first substrate 10.

[0070] As shown in FIG. 4, the first substrate 10 is rectangular in plan view and has a first side 10a, a second side 10b continuous with the first side 10a, a third side 10c continuous with the second side 10b, and a fourth side 10d continuous with the third side 10c.

[0071] 4, the solid-line circular portion indicates a first end 311a of the first via conductor 311, and the dotted-line circular portion indicates a second end 311b of the first via conductor 311. The chain lines shown in FIG. 4 are imaginary lines connecting the midpoints of two sides of the first substrate 10 that face each other across the center of the main surface (e.g., first face 101) of the first substrate 10, and imaginary lines connecting the vertices of two corners of the first substrate 10 that face each other across the center. The first via conductors 311 located on the outermost periphery of the first surface layer 111 are located on the chain lines shown in FIG. 4.

[0072] 4 , for a first via conductor 311 located at the corner between the first side 10a and the second side 10b, the distance between the first side 10a and the first end 311a is L11, the distance between the first side 10a and the second end 311b is L12, the distance between the second side 10b and the first end 311a is L21, and the distance between the second side 10b and the second end 311b is L22. In this case, the first via conductor 311 located at the corner between the first side 10a and the second side 10b may be inclined so that L11<L12 and L21<L22 are satisfied. In other words, the first via conductor 311 may be inclined so that the second end 311b is located closer to the center of the first substrate 10 than the first end 311a.

[0073] In this way, the first via conductor 311 of the embodiment is inclined not only in the direction along the first side 10a but also in the direction along the second side 10b, and therefore extends even less in the thickness direction of the wiring substrate 1 in the event of thermal expansion than, for example, a via conductor that is inclined only in the direction along the first side 10a.

[0074] Therefore, according to the wiring board 1 according to the embodiment, the bonding reliability between the first base material 10 and the second base material 20 is further improved.

[0075] For the first via conductor 311 located at the corner between the second side 10b and the third side 10c, the distance between the second side 10b and the first end 311a is L23, the distance between the second side 10b and the second end 311b is L24, the distance between the third side 10c and the first end 311a is L31, and the distance between the third side 10c and the second end 311b is L32. In this case, the first via conductor 311 located at the corner between the second side 10b and the third side 10c may be inclined so as to satisfy L23<L24 and L31<L32.

[0076] For the first via conductor 311 located at the corner between the third side 10 c and the fourth side 10 d, the distance between the third side 10 c and the first end 311 a is L33, the distance between the third side 10 c and the second end 311 b is L34, the distance between the fourth side 10 d and the first end 311 a is L41, and the distance between the fourth side 10 d and the second end 311 b is L42. In this case, the first via conductor 311 located at the corner between the third side 10 c and the fourth side 10 d may be inclined so as to satisfy L33<L34 and L41<L42.

[0077] For the first via conductor 311 located at the corner of the fourth side 10d and the first side 10a, the distance between the fourth side 10d and the first end 311a is L43, the distance between the fourth side 10d and the second end 311b is L44, the distance between the first side 10a and the first end 311a is L13, and the distance between the first side 10a and the second end 311b is L14. In this case, the first via conductor 311 located at the corner of the fourth side 10d and the first side 10a may be inclined so as to satisfy L43<L44 and L13<L14.

[0078] In this way, each of the multiple first via conductors 311 located at the four corners of the first substrate 10 may be inclined so that the second end 311b is located closer to the center of the first substrate 10 than the first end 311a.

[0079] In the first via conductor 311 according to the embodiment, the force acting in the in-plane direction on the second substrate 20 from one of the four first via conductors 311 located at the four corners is reduced by the force acting in the in-plane direction on the second substrate from the other first via conductors 311 located diagonally from this first via conductor 311. Therefore, according to the wiring board 1 according to the embodiment, it is possible to make it more difficult for misalignment to occur in the in-plane direction between the first substrate 10 and the second substrate 20.

[0080] Next, the specific configuration of the first via conductor 311 located on the surface layer of the first substrate 10, among the via conductors 31 of the first wiring 30, will be described with reference to FIG. 5. FIG. 5 is a schematic cross-sectional view showing an enlarged portion of the wiring board 1 according to the embodiment. Note that FIG. 5 shows a cross-sectional view taken along the arrow II shown in FIG. 2, and is an enlarged view of the cross-sectional view shown in FIG. 1. Specifically, FIG. 5 shows an example of a cross-sectional view of the semiconductor device 100 cut along a plane that is parallel to the stacking direction of the multiple ceramic layers 11 (here, the Z-axis direction) and passes through the center of the first substrate 10.

[0081] As shown in FIG. 5 , the first wiring 30 may have a second via conductor 312 that is a via conductor that penetrates a second surface layer 112 that is one of the surface layers of the first substrate 10 .

[0082] In the wiring board 1 according to the embodiment, the second via conductors 312 may be inclined with respect to the thickness direction of the first substrate 10, in other words, with respect to the stacking direction of the plurality of ceramic layers 11. Specifically, the inclination angle of the second via conductors 312 with respect to the thickness direction of the first substrate 10 may be larger than the inclination angle of the third via conductors 411 (see FIG. 3 ) with respect to the thickness direction of the first substrate 10.

[0083] As a result, in the wiring board 1 of the embodiment, when the second substrate 20 is also located on the second surface layer 112 (see Figure 8 described below), or when other components such as a motherboard are attached to the second surface layer 112, the effect of changes in the dimensions of the second via conductor 312 due to thermal expansion can be reduced.

[0084] 5, thickness T1 of first surface layer 111 may be thinner than thickness T3 of inner layer 113. By reducing the thickness of first surface layer 111, even when first via conductor 311 is inclined, it is possible to reduce the length of the electrical path of first wiring 30.

[0085] Furthermore, thickness T2 of second surface layer 112 may be thinner than thickness T3 of inner layer 113. By reducing the thickness of second surface layer 112, even when second via conductor 312 is inclined, it is possible to prevent the electrical path of first wiring 30 from becoming longer.

[0086] <Convex Body> Fig. 6 is an enlarged cross-sectional view showing an example of the configuration of portion H1 shown in Fig. 3. As shown in Fig. 6, the wiring substrate 1 may have a plurality of convex bodies 131. The plurality of convex bodies 131 protrude from the first surface 101 of the first substrate 10 toward the second substrate 20, and may extend into the interior of the second substrate 20.

[0087] The wiring board 1 having the above configuration can increase the bonding strength between the first substrate 10 and the second substrate 20 due to the anchor effect that occurs when the multiple convex bodies 131 penetrate into the interior of the second substrate 20.

[0088] By firmly bonding the second substrate 20 to the first substrate 10, the second substrate 20 is constrained by the first substrate 10, reducing thermal deformation of the second substrate 20. This makes it less likely for misalignment to occur between the first wiring 30 and the second wiring 40. Furthermore, by bonding the first substrate 10 and the second substrate 20 using a plurality of convex bodies 131, the need to bond the first substrate 10 and the second substrate 20 using, for example, a bonding material or the like is reduced.

[0089] The convex bodies 131 may contain a silica component. In this case, the convex bodies 131 may be bonded to the first substrate 10 by the silica component. In this case, the bonding strength between the first substrate 10 containing a glass component and the plurality of convex bodies 131 can be increased. Therefore, by increasing the bonding strength between the first substrate 10 and the second substrate 20, misalignment between the first substrate 10 and the second substrate 20 becomes less likely to occur. This stabilizes the physical connection between the first wiring 30 and the second wiring 40.

[0090] Furthermore, the convex body 131 firmly bonded to the first substrate 10 is unlikely to come off the first substrate 10 even when it is repeatedly subjected to loads caused by deformation of the second substrate 20. Therefore, according to the wiring board 1, the first substrate 10 and the second substrate 20 can be maintained in a state in which they are firmly bonded for a long period of time.

[0091] Fig. 7 is an enlarged cross-sectional view showing an example of the configuration of portion H2 shown in Fig. 6. As shown in Fig. 7, the convex body 131 may include a base portion 131b mainly composed of a ceramic component and a plurality of ceramic particles 133.

[0092] The base 131b may have a tapered shape. Specifically, in a cross section perpendicular to the first surface 101 of the first substrate 10, the width of the tip 131a of the base 131b may be narrower than the width of the base end 131d of the base 131b. As will be described later, a plurality of ceramic particles 133 are located on the surface of the base 131b, but if the base 131b has a tapered shape, the convex body 131 also has a tapered shape when viewed as a whole.

[0093] The convex body 131 having a tapered shape easily penetrates into the second substrate 20, and is therefore likely to produce an anchor effect. Furthermore, if the convex body 131 has a tapered shape, the convex body 131 may not penetrate into the second substrate 20, and a space may be generated between the first substrate 10 and the second substrate 20. Such a space may deteriorate the bonding strength between the first substrate 10 and the second substrate 20.

[0094] In contrast, with a wiring substrate 1 having a tapered convex body 131, the convex body 131 can easily penetrate into the interior of the second substrate 20, making it less likely that a space will be created between the first substrate 10 and the second substrate 20.

[0095] In a cross section perpendicular to the first surface 101, the side surface 131c connecting the tip end 131a and the base end 131d of the convex body 131 may be curved in a concave shape. The convex body 131 having such a configuration can more easily penetrate into the second base material 20 compared to, for example, a case in which the side surface is convex.

[0096] The tip 131a of the convex body 131 may be sharp. The convex body 131 with the sharp tip 131a can easily penetrate into the second substrate 20. When the convex body 131 is observed at a magnification of 5000 times using an optical microscope or an electron microscope, if no flat surface can be confirmed at the tip 131a, the tip 131a of the convex body 131 is sharp.

[0097] The height (length in the Z-axis direction) of the convex body 131 may be, for example, not less than 0.0001 mm and not more than 0.001 mm.

[0098] The content of the ceramic component in the convex body 131 may be higher than the content of the glass component in the first substrate 10. With this configuration, the workability of the convex body 131 is improved compared to when the convex body 131 is made of other materials, such as ceramic, and it is therefore easier to make the convex body 131 in a desired shape (for example, a tapered shape).

[0099] The plurality of ceramic particles 133 may be located on the surface of the base 131b. In this case, the ceramic particles 133 form fine irregularities on the surface of the base 131b. The second substrate 20 penetrates into the fine irregularities formed by the ceramic particles 133, making it more difficult for the convex body 131 to come off the second substrate 20. Therefore, the convex body 131 having the plurality of ceramic particles 133 has an even stronger anchoring effect.

[0100] Note that some of the plurality of ceramic particles 133 may be located inside the base 131b. In this case, the plurality of ceramic particles 133 may be located more on the surface of the base 131b than inside the base 131b. By adopting such a configuration, it is possible to enhance the anchoring effect while maintaining the strength of the base 131b, which is mainly composed of ceramic components.

[0101] Note that the term "ceramic particles 133 located on the surface of base 131b" refers to ceramic particles 133 at least a portion of which is exposed from base 131b in a cross-sectional view. Therefore, for example, ceramic particles 133 with a portion embedded inside base 131b also fall under the category of "ceramic particles 133 located on the surface of base 131b."

[0102] Furthermore, the phrase "more ceramic particles 133 are located on the surface of base 131b than inside base 131b" may mean, for example, that in a cross-sectional view, the number of ceramic particles 133 located on the surface of base 131b is greater than the number of ceramic particles 133 located inside base 131b.

[0103] 6 , the first substrate 10 may have a plurality of “recesses 132” on the first surface 101. In this case, the second substrate 20 may be recessed into the recesses 132. In such a configuration, the second substrate 20 recessed into the recesses 132 provides an anchor effect, thereby enabling the first substrate 10 and the second substrate 20 to be bonded more firmly.

[0104] Second Embodiment In the first embodiment described above, an example has been described in which the second substrate 20 is located on only one of the main surfaces (first surface 101 and second surface 102) of the first substrate 10 in the wiring board 1. However, the present invention is not limited to this, and the wiring board 1 may have a configuration in which the second substrate 20 is located on both main surfaces of the first substrate 10.

[0105] 8 is a cross-sectional view showing an example of the configuration of the wiring board 1 according to the second embodiment. As shown in FIG. 8, the wiring board 1 has a second substrate 20 located on a second surface 102 of the first substrate 10 in addition to a second substrate 20 located on a first surface 101 of the first substrate 10.

[0106] The second substrate 20 located on the second surface 102 has, for example, a third surface 103 joined to the second surface 102 of the first substrate 10. Note that the second substrate 20 may have a fourth surface 104 joined to the second surface 102 of the first substrate 10.

[0107] As described above, the first wiring 30 may have the second via conductor 312, which is a via conductor that penetrates the second surface layer 112, which is one of the surface layers of the first base material 10 (see FIG. 5 ). In the wiring board 1 having such a configuration, the second base material 20 is less susceptible to the influence of changes in the dimensions of the second via conductor 312 due to thermal expansion.

[0108] The disclosed embodiments should be considered in all respects as illustrative and not restrictive. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

[0109] The technology can be configured as follows: (1) A wiring board comprising: a first substrate having a first surface and a second surface opposite the first surface, the first substrate being made of a ceramic composite material containing a glass component; a second substrate having a third surface bonded to the first surface and a fourth surface opposite the third surface, the second substrate being made of an organic component as a main component; a first wiring located inside the first substrate and extending from the first surface to the second surface; and a second wiring located inside the second substrate and extending from the third surface to the fourth surface; the first substrate has a plurality of ceramic layers including a first surface layer having the first surface and a second surface layer having the second surface; the second substrate has a plurality of organic resin layers including a third surface layer having the third surface; the first wiring has a first via conductor penetrating the first surface layer; the second wiring has a third via conductor penetrating the third surface layer; and an inclination angle of the first via conductor with respect to the thickness direction of the first substrate being greater than an inclination angle of the third via conductor with respect to the thickness direction of the first substrate. (2) The wiring board according to (1), wherein the first surface layer has a fifth surface located opposite the first surface, the first via conductor has a first end located on the first surface and a second end located on the fifth surface, and a distance from a line passing through a center of the first base material and parallel to a thickness direction of the first base material to the first end is longer than a distance from the line to the second end. (3) The wiring board according to (2), wherein the first wiring has a plurality of the first via conductors on the first surface layer, and when the first base material is viewed in cross section, some of the plurality of first via conductors are located on one outer periphery of the first surface layer and other parts are located on the other outer periphery of the first surface layer. (4) The wiring board according to (2) or (3), wherein the first substrate is quadrangular in plan view and has a first side, a second side continuous with the first side, a third side continuous with the second side, and a fourth side continuous with the third side, the first via conductor is located at a corner between the first side and the second side, the distance from the first side to the first end is shorter than the distance from the first side to the second end, and the distance from the second side to the first end is shorter than the distance from the second side to the second end.(5) The wiring board according to (4), wherein the first wiring has a plurality of the first via conductors on the first surface layer, and among the plurality of first via conductors, a first via conductor located at a corner between the second side and the third side has a distance from the second side to the first end shorter than a distance from the second side to the second end and a distance from the third side to the first end shorter than a distance from the third side to the second end, among the plurality of first via conductors, a first via conductor located at a corner between the third side and the fourth side has a distance from the third side to the first end shorter than a distance from the third side to the second end and a distance from the fourth side to the first end shorter than a distance from the fourth side to the second end, among the plurality of first via conductors, a first via conductor located at a corner between the fourth side and the first side has a distance from the fourth side to the first end shorter than a distance from the fourth side to the second end and a distance from the first side to the first end shorter than a distance from the first side to the second end. (6) The wiring board according to any one of (1) to (5), wherein the first wiring has a second via conductor penetrating the second surface layer, and an inclination angle of the second via conductor with respect to the thickness direction of the first base material is larger than an inclination angle of the third via conductor with respect to the thickness direction of the first base material. (7) The wiring board according to any one of (1) to (6), wherein the first wiring has a wiring layer located between two adjacent ceramic layers. (8) The wiring board according to (7), wherein the first wiring has a plurality of the wiring layers, and the plurality of wiring layers include: a first wiring layer located on the outer periphery of the first base material in the in-plane direction; and a second wiring layer located closer to the center of the first base material in the in-plane direction than the first wiring layer, and the thickness of the first wiring layer is larger than the thickness of the second wiring layer. (9) The wiring board according to any one of (1) to (8), wherein only the first wiring of the first wiring and the second wiring contains a silica component. (10) The wiring board according to any one of (1) to (9), wherein the plurality of ceramic layers have at least one inner layer between the first surface layer and the second surface layer, and the thickness of the first surface layer is thinner than the thickness of the inner layer.(11) The wiring board according to any one of (1) to (10), wherein the first wiring has a plurality of the first via conductors on the first surface layer, and when the first base material is viewed in cross section, an inclination angle of the first via conductors located in a central portion of the first surface layer is smaller than an inclination angle of the first via conductors located in an outer periphery of the first surface layer. (12) The wiring board according to any one of (1) to (11), wherein the wiring board has a plurality of convex bodies protruding from the first surface and extending into the second base material, wherein the second base material has a higher thermal expansion coefficient in a direction along the first surface than the first base material, the first wiring and the second wiring are electrically connected at a bonding surface between the first base material and the second base material, and the convex bodies contain a silica component and are bonded to the first base material by the silica component.

[0110] REFERENCE SIGNS LIST 1 wiring substrate 2 semiconductor element 3 motherboard 4 bonding portion 10 first base material 10a first side 10b second side 10c third side 10d fourth side 11 ceramic layer 12 organic resin layer 20 second base material 30 first wiring 31 via conductor 32 wiring layer 40 second wiring 41 via conductor 42 wiring layer 100 semiconductor device 101 first surface 102 second surface 103 third surface 104 fourth surface 105 fifth surface 111 first surface 112 second surface 113 inner layer 121 third surface 122 fourth surface 131 convex body 131a tip portion 131b base portion 131c side surface 131d base end portion 133 ceramic particle 132 recess 311 First via conductor 311a First end 311b Second end 312 Second via conductor 321 First wiring layer 322 Second wiring layer 411 Third via conductor

Claims

1. A wiring board comprising: a first substrate having a first surface and a second surface opposite the first surface, the first substrate being made of a ceramic composite material containing a glass component; a second substrate having a third surface bonded to the first surface and a fourth surface opposite the third surface, the second substrate being made primarily of an organic component; a first wiring located inside the first substrate and extending from the first surface to the second surface; and a second wiring located inside the second substrate and extending from the third surface to the fourth surface; the first substrate has a plurality of ceramic layers including a first surface layer having the first surface and a second surface layer having the second surface; the second substrate has a plurality of organic resin layers including a third surface layer having the third surface; the first wiring has a first via conductor penetrating the first surface layer; the second wiring has a third via conductor penetrating the third surface layer; and the inclination angle of the first via conductor with respect to the thickness direction of the first substrate is greater than the inclination angle of the third via conductor with respect to the thickness direction of the first substrate.

2. The wiring board according to claim 1, wherein the first surface layer has a fifth surface located opposite the first surface, the first via conductor has a first end located on the first surface and a second end located on the fifth surface, and the distance from a straight line passing through the center of the first substrate and parallel to the thickness direction of the first substrate to the first end is longer than the distance from the straight line to the second end.

3. The wiring board according to claim 2, wherein the first wiring has a plurality of the first via conductors on the first surface layer, and when the first base material is viewed in cross section, some of the plurality of the first via conductors are located on one outer periphery of the first surface layer, and some are located on the other outer periphery of the first surface layer.

4. The wiring board according to claim 2 or 3, wherein the first substrate is quadrangular in plan view and has a first side, a second side continuous with the first side, a third side continuous with the second side, and a fourth side continuous with the third side, the first via conductor is located at a corner between the first side and the second side, the distance from the first side to the first end is shorter than the distance from the first side to the second end, and the distance from the second side to the first end is shorter than the distance from the second side to the second end.

5. The wiring board according to claim 4, wherein the first wiring has a plurality of the first via conductors on the first surface layer; and among the plurality of first via conductors, a first via conductor located at a corner between the second side and the third side has a distance from the second side to the first end shorter than the distance from the second side to the second end and also shorter than the distance from the third side to the first end; among the plurality of first via conductors, a first via conductor located at a corner between the third side and the fourth side has a distance from the third side to the first end shorter than the distance from the third side to the second end and also shorter than the distance from the fourth side to the first end; and among the plurality of first via conductors, a first via conductor located at a corner between the fourth side and the first side has a distance from the fourth side to the first end shorter than the distance from the fourth side to the second end and also shorter than the distance from the first side to the second end.

6. A wiring board according to any one of claims 1 to 5, wherein the first wiring has a second via conductor penetrating the second surface layer, and the inclination angle of the second via conductor relative to the thickness direction of the first substrate is greater than the inclination angle of the third via conductor relative to the thickness direction of the first substrate.

7. The wiring board according to any one of claims 1 to 6, wherein the first wiring has a wiring layer located between two adjacent ceramic layers.

8. The wiring board according to claim 7, wherein the first wiring has a plurality of wiring layers, and the plurality of wiring layers include a first wiring layer located on the outer periphery of the first substrate in the in-plane direction, and a second wiring layer located closer to the center of the first substrate in the in-plane direction than the first wiring layer, and the thickness of the first wiring layer is greater than the thickness of the second wiring layer.

9. The wiring board according to any one of claims 1 to 8, wherein of the first wiring and the second wiring, only the first wiring contains a silica component.

10. A wiring board according to any one of claims 1 to 9, wherein the plurality of ceramic layers have at least one inner layer between the first surface layer and the second surface layer, and the thickness of the first surface layer is thinner than the thickness of the inner layer.

11. A wiring board according to any one of claims 1 to 10, wherein the first wiring has a plurality of the first via conductors on the first surface layer, and when the first base material is viewed in cross section, the inclination angle of the first via conductors located in the center of the first surface layer is smaller than the inclination angle of the first via conductors located in the outer periphery of the first surface layer.

12. A wiring board as described in any one of claims 1 to 11, having a plurality of convex bodies protruding from the first surface and penetrating into the second substrate, wherein the second substrate has a higher coefficient of thermal expansion in a direction along the first surface than the first substrate, wherein the first wiring and the second wiring are electrically connected at the bonding surface between the first substrate and the second substrate, and wherein the convex bodies contain a silica component and are bonded to the first substrate by the silica component.

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