Wiring board

Abstract

To provide a technique capable of reducing the stress applied to a conductor or an inorganic base material on a junction interface between an inorganic layer and an organic layer.SOLUTION: A wiring board comprises an inorganic base material, an organic base material, a joint layer, and a conductor. The inorganic base material includes an inorganic component as a main component. The organic base material includes a first organic component as a main component and has a higher coefficient of thermal expansion than the inorganic base material. The joint layer is located between the inorganic base material and the organic base material and joined to the inorganic base material and the organic base material, and includes a second organic component. The conductor is located inside the inorganic base material and the joint layer. The inorganic base material has a first through hole penetrating the inorganic base material. The joint layer has a second through hole penetrating the joint layer and communicating with the first through hole. The conductor extends along a side face of the first through hole and a side face of the second through hole. The diameter of the second through hole is larger than the diameter of the first through hole.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] 2. Description of the Related Art A wiring board is known in which an organic layer on which wiring is formed is laminated on a glass cloth substrate as a core material.

[0003] A through-hole portion is formed in the glass cloth substrate, and the through-hole portion has a through-hole that penetrates the glass cloth substrate and a conductor located inside the through-hole (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-111608 Summary of the Invention [Problem to be solved by the invention]

[0005] The present inventors have discovered that when the core material is changed from a glass cloth substrate to an inorganic substrate to improve the strength of a wiring board, new problems may arise due to the difference in thermal expansion coefficient between the core material and the organic layer. For example, if the difference in thermal expansion coefficient between the core material and the organic layer is large, stress may be applied to the conductor or inorganic substrate located at the bonding interface between the core material and the organic layer, which may cause cracks in the conductor or inorganic substrate.

[0006] The present disclosure provides a technique capable of reducing stress applied to a conductor or an inorganic substrate at the bonding interface between an inorganic layer and an organic layer. [Means for solving the problem]

[0007] The wiring board of the present disclosure includes an inorganic base material, an organic base material, a bonding layer, and a conductor. The inorganic base material is primarily composed of an inorganic component. The organic base material is primarily composed of a first organic component and has a higher thermal expansion coefficient than the inorganic base material. The bonding layer is located between the inorganic base material and the organic base material, bonding to the inorganic base material and the organic base material, and contains a second organic component. The conductor is located inside the inorganic base material and the bonding layer. The inorganic base material has a first through hole penetrating the inorganic base material. The bonding layer has a second through hole penetrating the bonding layer and communicating with the first through hole. The conductor extends along side surfaces of the first through hole and the second through hole. The diameter of the second through hole is larger than the diameter of the first through hole. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to reduce stress applied to the conductor or inorganic substrate at the bonding interface between the inorganic layer and the organic layer. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view showing the configuration of a semiconductor device according to an embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view showing the configuration of the base substrate according to the embodiment. [Figure 3] FIG. 3 is a schematic enlarged view of region III shown in FIG. [Figure 4] FIG. 4 is a schematic enlarged view of a configuration in which the inside of the first conductor is filled with organic resin. [Figure 5] FIG. 5 is a schematic enlarged view of a configuration in which the first conductor has a tapered shape. [Figure 6] FIG. 6 is a schematic enlarged view of a configuration in which the first conductor has a tapered shape. [Figure 7] FIG. 7 is a schematic enlarged view of a configuration including an intervening layer. [Figure 8] FIG. 8 is a schematic cross-sectional view showing the configuration of the relay substrate and its surroundings according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments for carrying out a composite wiring board and a semiconductor device according to the present disclosure (hereinafter referred to as "embodiments") will be described in detail with reference to the drawings. Note that the present disclosure is not limited to these embodiments. Furthermore, the embodiments can be appropriately combined within the scope of not causing any contradiction in the processing content. Furthermore, the same components in the following embodiments will be given the same reference numerals, and duplicated explanations will be omitted.

[0011] Furthermore, in the following embodiments, expressions such as "constant," "orthogonal," "perpendicular," or "parallel" may be used, but these expressions do not necessarily mean "constant," "orthogonal," "perpendicular," or "parallel" in the strict sense. In other words, the above expressions allow for deviations due to, for example, manufacturing precision, installation precision, etc.

[0012] In addition, in the drawings referred to below, for ease of understanding, an orthogonal coordinate system may be shown in which the X-axis, Y-axis, and Z-axis directions are defined as being perpendicular to each other, and the positive Z-axis direction is the vertically upward direction.

[0013] First, the configuration of a semiconductor device 100 according to the embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic cross-sectional view showing the configuration of a semiconductor device 100 according to the embodiment.

[0014] As shown in FIG. 1, the semiconductor device 100 includes a motherboard 1, a wiring board 2, and a plurality of semiconductor elements 3.

[0015] The wiring board 2 includes a base substrate 4 and a relay substrate 5 .

[0016] The base substrate 4 is mounted on the motherboard 1. Details of the base substrate 4 will be described later.

[0017] The relay substrate 5 is a so-called interposer. The relay substrate 5 relays the electrical connection between the base substrate 4 and the semiconductor element 3. The relay substrate 5 is bonded to the semiconductor element 3 via a bonding material 6, and is also bonded to the base substrate 4 via a bonding material 7.

[0018] The Young's modulus of the relay substrate 5 may be smaller than that of the base substrate 4. In this case, the relay substrate 5 may have flexibility that allows it to deform according to the shape of the surface of the base substrate 4. The bonding materials 6 and 7 are, for example, solder. The relay substrate 5 will be described in detail later.

[0019] The semiconductor element 3 is mounted on an intermediate substrate 5. The semiconductor element 3 is, for example, 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 semiconductor chip or a glass substrate. The chiplet is a functional block that constitutes part of the integrated circuit of the semiconductor device 100.

[0020] 1 shows two semiconductor elements 3, the semiconductor device 100 may include three or more semiconductor elements 3. The semiconductor device 100 may also include only one semiconductor element 3. For example, if the semiconductor element 3 is a chiplet, a plurality of semiconductor elements 3 may form an integrated circuit having one function.

[0021] Next, the configuration of the base substrate 4 according to the embodiment will be described with reference to FIGS. 2 to 7. FIG. 2 is a schematic cross-sectional view showing the configuration of the base substrate 4 according to the embodiment. FIG. 3 is a schematic enlarged view of region III shown in FIG. 2. FIG. 4 is a schematic enlarged view of a configuration in which the inside of the first conductors 30 is filled with an organic resin. FIGS. 5 and 6 are schematic enlarged views of a configuration in which the first conductors 30 have a tapered shape. FIG. 7 is a schematic enlarged view of a configuration in which an intermediate layer 16 is provided.

[0022] The base substrate 4 has a first inorganic base material 10, a first organic base material 20, and a bonding layer 25. The base substrate 4 is a laminate of the first inorganic base material 10 and the first organic base material 20. The base substrate 4 also has first conductors 30 and second conductors 40.

[0023] <First inorganic base material> The first inorganic substrate 10 is a ceramic substrate primarily composed of inorganic components. The first inorganic substrate 10 may be formed using a ceramic composite material containing a glass component, known as glass ceramic. The glass ceramic may be any of the following: a composite of a glass phase and ceramic particles; a composite of a glass phase and a crystalline phase formed by partial crystallization of the glass phase; a composite in which ceramic particles exist in the glass phase; and a composite in which a glass phase exists at the grain boundaries between ceramic particles. The first inorganic substrate 10 formed using ceramic in this manner has higher rigidity than a glass core material.

[0024] For example, the first inorganic base material 10 may be made of LTCC (Low Temperature Co-fired Ceramics). When LTCC is used as the first inorganic base material 10, the first inorganic base material 10 can be fired at a low temperature, and therefore a low-melting-point metal such as copper or silver, which has a relatively low electrical resistance, can be used as wiring. In this embodiment, a low-melting-point metal is a metal with a melting point lower than that of typical metals used for wiring in ceramic base materials, such as tungsten or molybdenum.

[0025] The first inorganic substrate 10 may contain a ceramic filler as ceramic particles. Examples of ceramic fillers that can be used include alumina (aluminum oxide), calcium titanate, and magnesium titanate. In particular, the first inorganic substrate 10 containing alumina has high rigidity.

[0026] The first inorganic substrate 10 has a first surface 101 and a second surface 102 located on the opposite side to the first surface 101. The first inorganic substrate 10 may be a plate-like body having the first surface 101 and the second surface 102 as its main surfaces. The first inorganic substrate 10 has first through holes 12 that penetrate from the first surface 101 to the second surface 102.

[0027] In the embodiment, the first inorganic substrate 10 may have one ceramic layer 11. In the example shown in Figures 1 and 2, the first inorganic substrate 10 has one ceramic layer 11, but the number of ceramic layers 11 is not limited to one. The number of ceramic layers 11 may be multiple.

[0028] When there are multiple ceramic layers 11, the multiple ceramic layers 11 are stacked along the thickness direction of the first inorganic base material 10. A base substrate 4 having such a first inorganic base material 10 has a high degree of freedom in design. Furthermore, by forming the first inorganic base material 10 using multiple ceramic layers 11, the first inorganic base material 10 can be produced while checking whether the first conductors 30 are properly formed for each layer, thereby improving the yield of the first inorganic base material 10.

[0029] <First organic base material and bonding layer> The first organic base material 20 is mainly composed of a first organic component. The first organic base material 20 has a higher thermal expansion coefficient than the first inorganic base material 10. The first organic component may be an organic resin. The organic resin may be, for example, an epoxy resin containing silica particles, a polyimide resin, an acrylic resin, a polycarbonate resin, an olefin resin, or a polyphenylene resin.

[0030] For example, epoxy resin has excellent heat resistance, pressure resistance, water resistance, and chemical resistance. This allows the wiring board 2 to improve the heat resistance, pressure resistance, and chemical resistance of the first organic base material 20 against chemical treatment with hydrogen fluoride and the like. Furthermore, polyimide resin has inferior chemical resistance against alkaline chemical treatment compared to epoxy resin, but has even better heat resistance. This allows the wiring board 2 to improve the heat resistance of the first organic base material 20.

[0031] The organic resin may be, for example, polytetrafluoroethylene (PTFE) or other fluororesins or polyphenylene ether resins. The first organic base material 20 may contain components other than the organic resin. In the present disclosure, a "major component" refers to a material that accounts for, for example, 50% or more by volume of the material.

[0032] The first organic base material 20 has a third surface 103 and a fourth surface 104 located on the opposite side to the third surface 103. The first organic base material 20 may be a plate-like body having the third surface 103 and the fourth surface 104 as main surfaces.

[0033] The bonding layer 25 is a layer located between the first inorganic substrate 10 and the first organic substrate 20 and bonds to the first inorganic substrate 10 and the first organic substrate 20, respectively. The bonding layer 25 includes a second organic component. The bonding layer 25 has a higher thermal expansion coefficient than the first inorganic substrate 10. The second organic component may be an organic resin. The organic resin may be, for example, an epoxy resin, polyimide resin, acrylic resin, polycarbonate resin, olefin resin, or polyphenylene resin containing silica particles. The organic resin contained in the bonding layer 25 may be the same as the organic resin contained in the first organic substrate 20 described above. Furthermore, the particle diameter of the silica contained in the first organic substrate 20 described above may be larger than the particle diameter of the silica contained in the bonding layer 25.

[0034] For example, epoxy resin has excellent heat resistance, pressure resistance, water resistance, and chemical resistance. This allows the heat resistance, pressure resistance, water resistance, and chemical resistance of bonding layer 25 of wiring board 2 to be improved. Furthermore, polyimide resin has even better heat resistance than epoxy resin. This allows the heat resistance of bonding layer 25 of wiring board 2 to be improved. Furthermore, by reducing the particle diameter of silica in bonding layer 25 of wiring board 2, the silica particles and resin components can easily penetrate into the uneven portions in the surface layer of the LTCC, thereby improving the adhesion (which can also be rephrased as bonding strength) between first inorganic base material 10 and bonding layer 25.

[0035] The content of the inorganic material, which is silica, in bonding layer 25 may be less than the content of the inorganic material in first organic base material 20. This makes the content of the organic material in bonding layer 25 greater than that in first organic base material 20, and therefore the surface layer of LTCC and the resin component are closely attached to each other, thereby improving the connection reliability of wiring board 2.

[0036] Bonding layer 25 has a fifth surface 105 and a sixth surface 106 located opposite to fifth surface 105. Bonding layer 25 may be a plate-like body having fifth surface 105 and sixth surface 106 as main surfaces. Bonding layer 25 has second through-holes 26 that penetrate from fifth surface 105 to sixth surface 106 and communicate with first through-holes 12.

[0037] The base substrate 4 according to the embodiment has two first organic base materials 20 and two bonding layers 25. One of the two first organic base materials 20 may be bonded to the first surface 101 of the first inorganic base material 10 via the bonding layer 25, and the other may be bonded to the second surface 102 of the first inorganic base material 10 via the bonding layer 25.

[0038] The first organic base material 20 is located on the first surface 101 of the first inorganic base material 10 via the bonding layer 25. A plurality of semiconductor elements 3 are mounted on the third surface 103 via the intermediate substrate 5, and the fourth surface 104 of the first organic base material 20 may be bonded to the fifth surface 105 of the bonding layer 25 (see FIG. 1 ). The sixth surface 106 of the bonding layer 25 may be bonded to the first surface 101 of the first inorganic base material 10.

[0039] The first organic base material 20 is located on the second surface 102 of the first inorganic base material 10 via the bonding layer 25, and has a third surface 103 bonded to the motherboard 1 via the bonding portion 8, and a fourth surface 104 of the first organic base material 20 may be bonded to a fifth surface 105 of the bonding layer 25 (see FIG. 1 ). A sixth surface 106 of the bonding layer 25 may be bonded to the second surface 102 of the first inorganic base material 10.

[0040] The first organic base material 20 may have a plurality of organic resin layers 21. The plurality of organic resin layers 21 are stacked along the thickness direction of the first organic base material 20. A base substrate 4 having such a first organic base material 20 has a high degree of freedom in design. In the example shown in FIG. 2, the first organic base material 20 has four organic resin layers 21, but the number of organic resin layers 21 is not limited to four. The number of organic resin layers 21 may be two, three, or five or more. The bonding layer 25 may be thinner than one organic resin layer 21.

[0041] 1 and 2 show an example in which the base substrate 4 has the bonding layer 25 and the first organic base material 20 on each of the first surface 101 and the second surface 102 of the first inorganic base material 10. However, the base substrate 4 is not limited to this, and it is sufficient that the base substrate 4 has the bonding layer 25 and the first organic base material 20 on at least the first surface 101 of the first inorganic base material 10.

[0042] The first organic base material 20, which is mainly composed of the first organic component, is easier to form a fine wiring pattern on than an inorganic substrate. On the other hand, the first inorganic base material 10 made of ceramic has higher rigidity than the first organic base material 20. The first inorganic base material 10 may have a higher density than the first organic base material 20.

[0043] The base substrate 4 according to the embodiment can increase rigidity while achieving finer wiring and narrower pitches by combining the first inorganic base material 10 and the first organic base material 20. Since warping of the substrate becomes more pronounced as the substrate becomes larger, the configuration of the base substrate 4 in which the first inorganic base material 10 compensates for the low rigidity of the first organic base material 20 is particularly useful for increasing the size of the substrate.

[0044] The first inorganic base material 10 and the bonding layer 25 are bonded together by, for example, hydrogen bonding. Specifically, the first inorganic base material 10 and the bonding layer 25 are bonded together by bonding between hydroxyl groups of the first inorganic base material 10 and the bonding layer 25. In this case, a ceramic material such as alumina having surface hydroxyl groups may be used for the first inorganic base material 10, and an epoxy resin, which is a resin material containing hydroxyl groups, may be used for the bonding layer 25. In this way, by directly bonding the first inorganic base material 10 and the bonding layer 25 without using solder, underfill, or the like, the thickness of the base substrate 4 can be reduced.

[0045] The first inorganic substrate 10 may contain a glass component, and the bonding layer 25 may contain a coupling agent that chemically bonds with the glass component. Examples of the coupling agent include a silane coupling agent. Examples of the coupling agent include a titanium-based coupling agent and an aluminum-based coupling agent. This configuration allows the first inorganic substrate 10 and the bonding layer 25 to be chemically bonded together, thereby more firmly bonding the first inorganic substrate 10 and the bonding layer 25, which are made of different materials.

[0046] In the wiring board 2, the first inorganic base material 10 and the bonding layer 25 are chemically bonded by a coupling agent. This allows the wiring board 2 to improve the bonding strength between the first inorganic base material 10 and the bonding layer 25, which are made of different materials.

[0047] <First Conductor> The first conductor 30 may have a first through-hole conductor 31 located in the first inorganic base material 10. The first conductor 30 may have a second through-hole conductor 32 on the first surface 101 and the second surface 102 of the first inorganic base material 10. The first conductor 30 may have a land 33 on the fifth surface 105 of the bonding layer 25. In the first conductor 30, the first through-hole conductor 31, the second through-hole conductor 32, and the land 33 are electrically connected to each other.

[0048] The first conductor 30 is mainly composed of metal and extends along the side surface of the first through hole 12 and the side surface of the second through hole 26. More specifically, in the first conductor 30, the first through-hole conductor 31 may be located in the first through hole 12 and extend along the side surface of the first through hole 12. In addition, in the first conductor 30, the second through-hole conductor 32 may be located in the second through hole 26 and extend along the side surface of the second through hole 26.

[0049] In the first conductor 30, the first through hole 12 may be filled with a first through-hole conductor 31, and the second through hole 26 may be filled with a second through-hole conductor 32. With this configuration, a via 41 (described later) can be formed vertically above the second through-hole conductor 32. In the first conductor 30, the side surface of the first through hole 12 is electrically connected by the first through-hole conductor 31, which is copper-plated, and the side surface of the second through hole 26 is electrically connected by the second through-hole conductor 32, which is copper-plated, and the insides of the first through-hole conductor 31 and the second through-hole conductor 32 may be filled with an organic resin (see FIG. 4).

[0050] The diameter R1 of the second through-hole conductor 32 is larger than the diameter L1 of the first through-hole conductor 31 (see FIG. 3). In other words, the diameter of the second through hole 26 is larger than the diameter of the first through hole 12. The diameter L2 of the land 33 is larger than the diameter R1 of the second through-hole conductor 32. The diameter here is not limited to a perfect circle, but may be a circle with a partially distorted shape or a circle with slight irregularities on the edge.

[0051] In the wiring board 2 according to the present disclosure, the difference in diameter between the first through hole 12 and the second through hole 26 forms a step in the first conductor 30, and the first inorganic base material 10 and the bonding layer 25 come into contact in a stepped manner at the portion where the step is formed, thereby dispersing the stress that the first conductor 30 receives from the first inorganic base material 10 and the bonding layer 25. This allows the wiring board 2 to reduce the stress that is applied to the first conductor 30 or the first inorganic base material 10 at the interface between the inorganic layer (here, the first inorganic base material 10) and the organic layer (here, the bonding layer 25).

[0052] The first conductors 30 may have a tapered shape that narrows from the first surface 101 of the first inorganic base material 10 toward the inside (see FIG. 5). In other words, the openings of the first through holes 12 (here, first openings 12a) may have a tapered shape that narrows from the surface (here, first surface 101) of the first inorganic base material 10 toward the inside. Here, narrow means that the width becomes smaller when the diameter of the first conductors 30 or the first through holes 12 is taken as the width.

[0053] The first through hole 12 may have a first opening 12a located on the first surface 101 and a second opening 12b located on the second surface 102. The second opening 12b may have a tapered shape that narrows from the second surface 102 toward the inside of the first inorganic base material 10 (see FIG. 6).

[0054] In wiring board 2, first opening 12a or second opening 12b has a tapered shape, so that the location where the triple point is formed can be moved away from the straight portion of first conductor 30. This allows wiring board 2 to further reduce the stress applied to first conductor 30 at the interface between the inorganic layer (here, first inorganic base material 10) and the organic layer (here, bonding layer 25). Note that the tapered shape of second opening 12b is not limited to the above-described tapered shape, and it may also be a tapered shape that widens from second surface 102 toward the inside.

[0055] The first conductor 30 may have a diameter L3 on the second surface 102 that is larger than the diameter L1 on the first surface 101 (see FIG. 6). In other words, the diameter of the second opening 12b on the second surface 102 may be larger than the diameter of the first opening 12a on the first surface 101.

[0056] The first inorganic base material 10 according to the present disclosure has a second surface 102 bonded to a motherboard 1 via a second organic base material 60 and a bonding portion 8 (see FIG. 1). The thermal expansion coefficient of the motherboard 1 is generally 30 to 60×10 -6 / °C, which is higher than that of the wiring board 2.

[0057] Furthermore, in the wiring board 2 according to the present disclosure, the diameter L3 of the second opening 12b on the second surface 102 of the first inorganic base material 10 is larger than the diameter L1 of the first opening 12a on the first surface 101. Therefore, the amount of the first conductors 30 located in the second opening 12b is greater than the amount of the first conductors 30 located in the first opening 12a. In other words, the proportion of the first conductors 30 on the second surface 102 side of the first inorganic base material 10 is greater than the proportion of the first conductors 30 on the first surface 101 side of the first inorganic base material 10. The metal constituting the first conductors 30 has a higher thermal expansion coefficient than the first inorganic base material 10. Therefore, by making the diameter of the second opening 12b larger than the diameter of the first opening 12a, the thermal expansion coefficient on the second opening 12b side can be made higher than the thermal expansion coefficient on the first opening 12a side. In other words, the thermal expansion coefficient of the second surface side bonded to the motherboard 1 can be made closer to the thermal expansion coefficient of the motherboard 1. This makes it possible to improve the reliability of mounting on the motherboard 1.

[0058] The surface roughness of the side surface of the first through hole 12 may be greater than the surface roughness of the first surface 101 of the first inorganic base material 10.

[0059] The first surface 101 of the first inorganic base material 10 is finished to have a smooth surface roughness in order to form fine wiring. The side surface of the first through hole 12 may have an uneven surface state in which a portion mainly composed of amorphous SiO2 has been removed in order to obtain good adhesion with the first conductor 30 and good plating film quality. This makes the surface roughness of the side surface of the first through hole 12 greater than the surface roughness of the first inorganic base material 10, and may improve adhesion between the side surface of the first through hole 12 and the first conductor 30.

[0060] An intervening layer 16 containing a third organic component may be provided, located between the side surface of the first through hole 12 and the first conductor 30 (see FIG. 7). For example, the third organic component may be an organic resin 17.

[0061] When the first through holes 12 of the first inorganic base material 10 are formed, SiO2 in a glassy state (see region 14) is removed from the surface layer of the side surface of the first through holes 12, leaving SiO2 in a crystalline state (see region 13), which may result in the formation of irregularities on the side surface of the first through holes 12. The glassy state is a state in which the atomic arrangement has no regularity or periodicity. The crystalline state is a state in which regular atomic unit structures are arranged periodically.

[0062] In the wiring board 2 of the present disclosure, the intervening layer 16 is located on the side surface of the first through hole 12. Therefore, even if the side surface of the first through hole 12 is uneven, the intervening layer 16 can fill in the unevenness and flatten the surface. This eliminates post-processing such as polishing. Therefore, the wiring board 2 of the present disclosure can reduce a decrease in yield even when a core material with low processability is used. Furthermore, in the wiring board 2 of the present disclosure, the bonding surface of the first conductor 30 is made of a material containing an organic component, similar to the first organic base material 20, thereby reducing variation in the bonding strength of the first conductor 30.

[0063] <Second Conductor> The second conductor 40 has a plurality of vias 41 and a plurality of lands 42. The vias 41 penetrate one or more organic resin layers 21. The lands 42 are located between adjacent organic resin layers 21 and electrically connect the plurality of vias 41 together.

[0064] The first conductor 30 and the second conductor 40 may be, for example, a metal conductor whose main component is copper or silver. For example, both the first conductor 30 and the second conductor 40 may be a metal conductor whose main component is copper. Alternatively, both the first conductor 30 and the second conductor 40 may be a metal conductor whose main component is silver. Alternatively, one of the first conductor 30 and the second conductor 40 may be a metal conductor whose main component is copper, and the other may be a metal conductor whose main component is silver.

[0065] By making all of the first conductor 30 and the second conductor 40 metal conductors whose main component is copper or silver, it is possible to obtain higher electrical properties compared to, for example, when one of the first conductor 30 and the second conductor 40 is made of a metal conductor other than copper or silver.

[0066] Of the first conductors 30 and the second conductors 40, only the first conductors 30 may contain a glass component. In this case, the first conductors 30 are firmly bonded to the first inorganic base material 10, which also contains a glass component, via the glass component. This allows the rigidity of the first inorganic base material 10 to be increased.

[0067] The second conductor 40 may be electrically and thermally connected to the semiconductor element 3 via the relay substrate 5. By thermally connecting the second conductor 40, which is mainly composed of copper or silver, which has a relatively high thermal conductivity, to the semiconductor element 3, which serves as a heat source, the heat generated from the semiconductor element 3 can be efficiently dissipated via the second conductor 40 and the first conductor 30.

[0068] Next, the configuration of the relay board 5 according to the embodiment will be described with reference to Fig. 8. Fig. 8 is a schematic cross-sectional view showing the configuration of the relay board 5 and its surroundings according to the embodiment.

[0069] The intermediate substrate 5 has a second inorganic base material 50 and a second organic base material 60. The intermediate substrate 5 is a laminate of the second inorganic base material 50 and the second organic base material 60. The intermediate substrate 5 also has a third conductor 70 and a fourth conductor 80.

[0070] <Second inorganic base material> The second inorganic substrate 50 is a ceramic substrate. The second inorganic substrate 50 may be formed using a ceramic composite material containing a glass component, known as glass ceramic. The glass ceramic may be any of the following: a composite of a glass phase and ceramic particles; a composite of a glass phase and a crystalline phase formed by partial crystallization of the glass phase; a composite in which ceramic particles exist in the glass phase; and a composite in which a glass phase exists at the grain boundaries between ceramic particles. The second inorganic substrate 50 formed using ceramic in this manner has higher rigidity than a glass core material.

[0071] For example, the second inorganic base material 50 may be made of LTCC (Low Temperature Co-fired Ceramics). When LTCC is used as the second inorganic base material 50, it is possible to use a low-melting-point metal such as copper or silver, which has a relatively low electrical resistance, as wiring.

[0072] The second inorganic base material 50 may contain a ceramic filler as ceramic particles. Examples of ceramic fillers that can be used include alumina (aluminum oxide), calcium titanate, and magnesium titanate. In particular, the second inorganic base material 50 containing alumina has high rigidity.

[0073] The second inorganic substrate 50 has a seventh surface 501 and an eighth surface 502 located on the opposite side to the seventh surface 501. The second inorganic substrate 50 may be a plate-like body having the seventh surface 501 and the eighth surface 502 as main surfaces. The second inorganic substrate 50 has third through-holes 51 that penetrate from the seventh surface 501 to the eighth surface 502.

[0074] <Second organic base material> The second organic base material 60 is a base material primarily composed of a fourth organic component. The fourth organic component may be an organic resin. The organic resin may be, for example, an epoxy resin, a polyimide resin, an acrylic resin, a polycarbonate resin, an olefin resin, or a polyphenylene resin.

[0075] The organic resin may be, for example, polytetrafluoroethylene (PTFE) or other fluororesins or polyphenylene ether resins. The second organic base material 60 may contain components other than the organic resin. In the present disclosure, a "major component" refers to a material that accounts for, for example, 50% or more by volume of the material.

[0076] The second organic base material 60 has a ninth surface 601 and a tenth surface 602 located on the opposite side to the ninth surface 601. The second organic base material 60 may be a plate-like body having the ninth surface 601 and the tenth surface 602 as main surfaces.

[0077] The second organic base material 60 has a ninth surface 601 bonded to the seventh surface 501 of the second inorganic base material 50 via a bonding material 9, and a plurality of semiconductor elements 3 are mounted on a tenth surface 602 of the second organic base material 60 via a bonding material 6 (see FIG. 1). The bonding material 9 is, for example, solder.

[0078] The second organic base material 60 has a plurality of organic resin layers 61. The plurality of organic resin layers 61 are stacked along the thickness direction of the second organic base material 60. The relay substrate 5 having such a second organic base material 60 has a high degree of freedom in design. In the example shown in FIG. 8, the second organic base material 60 has three organic resin layers 61, but the number of organic resin layers 61 is not limited to three. The number of organic resin layers 61 may be one or two, or may be four or more.

[0079] <Third Conductor> The third conductor 70 has a through-hole conductor 71 located in the second inorganic base material 50. Specifically, the third conductor 70 is mainly composed of metal and extends along the side surface of the third through hole 51.

[0080] The third conductor 70 also has lands 72 on the seventh surface 501 and the eighth surface 502 of the second inorganic base material 50 .

[0081] <Fourth Conductor> The fourth conductor 80 has a plurality of vias 81 and a plurality of lands 82. The vias 81 penetrate one or a plurality of organic resin layers 61. The lands 82 are located between adjacent organic resin layers 61 and electrically connect the plurality of vias 81 together. The lands 82 are formed integrally with the vias 81 located in the same organic resin layer 61.

[0082] The third conductor 70 and the fourth conductor 80 may be, for example, a metal conductor whose main component is copper or silver. For example, both the third conductor 70 and the fourth conductor 80 may be a metal conductor whose main component is copper. Alternatively, both the third conductor 70 and the fourth conductor 80 may be a metal conductor whose main component is silver. Alternatively, one of the third conductor 70 and the fourth conductor 80 may be a metal conductor whose main component is copper, and the other may be a metal conductor whose main component is silver.

[0083] By making all of the third conductor 70 and the fourth conductor 80 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 third conductor 70 and the fourth conductor 80 is made of a metal conductor other than copper or silver.

[0084] Of the third conductors 70 and the fourth conductors 80, only the third conductors 70 may contain a glass component. In this case, the third conductors 70 are firmly bonded to the second inorganic base material 50, which also contains a glass component, via the glass component. This allows the rigidity of the second inorganic base material 50 to be increased.

[0085] The fourth conductor 80 may be electrically and thermally connected to the semiconductor element 3 via the bonding material 6. By thermally connecting the fourth conductor 80, which is mainly composed of copper or silver, which has a relatively high thermal conductivity, to the semiconductor element 3, which serves as a heat source, the heat generated from the semiconductor element 3 can be efficiently dissipated via the fourth conductor 80 and the third conductor 70.

[0086] The relay board 5 configured as described above can have an increased rigidity by providing the second inorganic base material 50. The increased rigidity of the relay board 5 makes the relay board 5 less susceptible to warping, and therefore the flatness of the mounting surface of the relay board 5 on which the semiconductor element 3 is mounted can be increased.

[0087] The technical idea of ​​the present application can also be applied to the relay substrate 5. That is, the relay substrate 5 can have the same configuration as the base substrate 4, with the inorganic substrate being the second inorganic substrate 50, the organic substrate being the second organic substrate 60, and the conductor being the third conductor 70, and can achieve the same effects.

[0088] 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.

[0089] The present technology can also be configured as follows. (1) an inorganic base material containing an inorganic component as a main component; an organic base material containing a first organic component as a main component and having a thermal expansion coefficient higher than that of the inorganic base material; a bonding layer located between the inorganic base material and the organic base material and bonding to the inorganic base material and the organic base material, respectively, the bonding layer including a second organic component; a conductor located inside the inorganic base material and the bonding layer; Equipped with the inorganic substrate has a first through hole penetrating the inorganic substrate, the bonding layer has a second through hole penetrating the bonding layer and communicating with the first through hole; the conductor extends along a side surface of the first through hole and a side surface of the second through hole, The diameter of the second through hole is larger than the diameter of the first through hole. Wiring board. (2) The inorganic substrate is a low-temperature co-fired ceramic containing a glass component. The wiring board according to (1) above. (3) The bonding layer contains a coupling agent that chemically bonds with the glass component. The wiring board according to (1) or (2) above. (4) The opening of the first through hole has a tapered shape that narrows from the surface of the inorganic substrate toward the inside. The wiring board according to any one of (1) to (3). (5) the inorganic base material has a first surface bonded to the bonding layer, the first through hole has a first opening located in the first surface; The first opening has a tapered shape that narrows from the first surface toward the inside of the inorganic base material. The wiring board according to any one of (1) to (4). (6) the inorganic base material has a first surface bonded to the bonding layer and a second surface located opposite the first surface, the first through hole has a first opening located in the first surface and a second opening located in the second surface; The second opening has a tapered shape that narrows from the second surface toward the inside of the inorganic base material. The wiring board according to any one of (1) to (4). (7) the inorganic base material has a first surface bonded to the bonding layer and a second surface located opposite the first surface, the first through hole has a first opening located in the first surface and a second opening located in the second surface; The diameter of the second opening in the second surface is larger than the diameter of the first opening in the first surface. The wiring board according to (1) above. (8) The organic substrate comprises an epoxy resin or a polyimide resin containing silica particles. The wiring board according to any one of (1) to (7). (9) the bonding layer contains an epoxy resin or a polyimide resin containing silica particles; a particle diameter of the silica contained in the organic base material is larger than a particle diameter of the silica contained in the bonding layer; The wiring board according to (8) above. (10) The inorganic base material has a first surface bonded to the bonding layer, The surface roughness of the side surface of the first through hole is greater than the surface roughness of the first surface. The wiring board according to any one of (1) to (4). (11) an intervening layer located between a side surface of the first through hole and the conductor and including a third organic component; The wiring board according to any one of (1) to (10) above. [Explanation of symbols]

[0090] 1 Motherboard 2. Wiring board 10 First inorganic base material 12 First through hole 12a 1st opening 12b 2nd opening 16 Intervening layer 20 First organic base material 25 Bonding layer 26 Second through hole 101 Page 1 102 Side 2 103 3rd page 104 Page 4 L1 diameter L3 diameter R1 diameter

Claims

1. an inorganic base material containing an inorganic component as a main component; an organic base material containing a first organic component as a main component and having a thermal expansion coefficient higher than that of the inorganic base material; a bonding layer located between the inorganic base material and the organic base material and bonding to the inorganic base material and the organic base material, the bonding layer including a second organic component; a conductor located inside the inorganic base material and the bonding layer; Equipped with the inorganic substrate has a first through hole penetrating the inorganic substrate, the bonding layer has a second through hole penetrating the bonding layer and communicating with the first through hole; the conductor extends along a side surface of the first through hole and a side surface of the second through hole, The diameter of the second through hole is larger than the diameter of the first through hole. Wiring board.

2. The inorganic substrate is a low-temperature co-fired ceramic containing a glass component. The wiring board according to claim 1 .

3. The bonding layer contains a coupling agent that chemically bonds with the glass component. The wiring board according to claim 2 .

4. The opening of the first through hole has a tapered shape that narrows from the surface of the inorganic base material toward the inside. The wiring board according to claim 1 .

5. the inorganic base material has a first surface bonded to the bonding layer, the first through hole has a first opening located in the first surface; The first opening has a tapered shape that narrows from the first surface toward the inside of the inorganic base material. The wiring board according to claim 1 .

6. the inorganic base material has a first surface bonded to the bonding layer and a second surface located opposite the first surface, the first through hole has a first opening located in the first surface and a second opening located in the second surface; The second opening has a tapered shape that narrows from the second surface toward the inside of the inorganic base material. The wiring board according to claim 1 .

7. the inorganic base material has a first surface bonded to the bonding layer and a second surface located opposite the first surface, the first through hole has a first opening located in the first surface and a second opening located in the second surface; The diameter of the second opening in the second surface is larger than the diameter of the first opening in the first surface. The wiring board according to claim 1 .

8. The organic substrate comprises an epoxy resin or a polyimide resin containing silica particles. The wiring board according to claim 1 .

9. the bonding layer contains an epoxy resin or a polyimide resin containing silica particles; a particle diameter of the silica contained in the organic base material is larger than a particle diameter of the silica contained in the bonding layer; The wiring board according to claim 8 .

10. the inorganic base material has a first surface bonded to the bonding layer, The surface roughness of the side surface of the first through hole is greater than the surface roughness of the first surface. The wiring board according to claim 1 .

11. an intervening layer located between a side surface of the first through hole and the conductor and including a third organic component; The wiring board according to claim 1 .

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