Wiring board and semiconductor device

Abstract

A wiring board according to the present disclosure comprises: a first base material; a second base material that contains a plurality of inorganic particles and is made from an organic resin bonded to the first base material; and wiring that is located in the second base material. The first base material is more rigid than the second base material. The second base material includes a first layer having a relatively low inorganic particle content and a second layer that is laid on the first layer and has a relatively high inorganic particle content. The first layer is in contact with the first base material.

Description

Wiring board and semiconductor device

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

[0002] A wiring board is known in which an organic substrate having wiring formed thereon is laminated on a glass cloth substrate as a core material, and the organic substrate contains inorganic particles such as silica (Patent Document 1).

[0003] JP 2014-27212 A

[0004] A wiring board according to one embodiment of the present disclosure includes a first substrate, a second substrate made of an organic resin containing a plurality of inorganic particles and bonded to the first substrate, and wiring located on the second substrate. The first substrate has higher rigidity than the second substrate. The second substrate includes a first layer having a relatively low content of inorganic particles and a second layer laminated on the first layer and having a relatively high content of inorganic particles. The first layer is in contact with the first substrate.

[0005] FIG. 1 is a schematic cross-sectional view showing a state in which a semiconductor device according to the first embodiment is mounted on a motherboard. FIG. 2 is a schematic cross-sectional view showing the configuration of a wiring substrate according to the first embodiment. FIG. 3 is a schematic cross-sectional view showing the configuration of a second substrate according to the first embodiment. FIG. 4 is a schematic cross-sectional view showing the configurations of a first substrate and a second substrate according to the first embodiment. FIG. 5 is a schematic cross-sectional view showing the configuration of a first layer and its periphery according to the first embodiment. FIG. 6 is a schematic cross-sectional view showing the configuration of a second substrate according to the second embodiment.

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

[0007] 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 or installation precision.

[0008] In addition, in the drawings referred to below, for ease of understanding, 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 positive Z-axis direction is the vertically upward direction.

[0009] While inorganic particles have the effect of reducing the thermal expansion coefficient of organic resin substrates, which have a relatively high thermal expansion coefficient, they may also reduce the adhesion between the organic resin substrate and the core material.

[0010] The present disclosure provides a technique that can improve the adhesion between an organic resin substrate and a core material while reducing the thermal expansion coefficient of the organic resin substrate by using inorganic particles.

[0011] First Embodiment First, the configuration of a semiconductor device 100 according to a first embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic cross-sectional view showing a state in which the semiconductor device 100 according to the first embodiment is mounted on a motherboard 4.

[0012] As shown in FIG. 1, the semiconductor device 100 includes a wiring substrate 1 , a plurality of semiconductor elements 2 , and an intermediate substrate 3 .

[0013] The wiring board 1 is mounted on a motherboard 4. Details of the wiring board 1 will be described later.

[0014] The semiconductor element 2 is mounted on the wiring substrate 1 via an intermediate substrate 3. The semiconductor element 2 is, for example, a chip or chiplet in which a circuit or element is 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.

[0015] 1 shows two semiconductor elements 2, the semiconductor device 100 may include three or more semiconductor elements 2. The semiconductor device 100 may also include only one semiconductor element 2. For example, if the semiconductor element 2 is a chiplet, an integrated circuit having one function may be configured by a plurality of semiconductor elements 2.

[0016] The relay substrate 3 is a so-called interposer, and relays the electrical connection between the wiring substrate 1 and the semiconductor element 2. The relay substrate 3 is joined to the semiconductor element 2 via a joint 5, and is joined to the wiring substrate 1 via a joint 6. The joints 5 and 6 are, for example, solder. The Young's modulus of the relay substrate 3 may be smaller than that of the wiring substrate 1. In this case, the relay substrate 3 may have flexibility that allows it to deform according to the shape of the surface of the wiring substrate 1.

[0017] Next, the configuration of the wiring board 1 according to the first embodiment will be described with reference to Fig. 2. Fig. 2 is a schematic cross-sectional view showing the configuration of the wiring board 1 according to the first embodiment.

[0018] The wiring board 1 has a first base material 10 and a second base material 20. The wiring board 1 is a laminate of the first base material 10 and the second base material 20. The wiring board 1 also has a first wiring 30 and a second wiring 40.

[0019] <First Substrate> The first substrate 10 is a ceramic substrate. The first 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 a composite of a glass phase and ceramic particles, a composite of a glass phase and a crystalline phase formed by the crystallization of a portion of the glass phase, a form in which ceramic particles exist in the glass phase, and a form in which a glass phase exists at the grain boundaries between ceramic particles. The first substrate 10 formed using ceramic in this manner has higher rigidity than a glass core material.

[0020] 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. In this embodiment, the low-melting-point metal is a metal with a melting point lower than that of typical metals used for wiring in ceramic substrates, such as tungsten or molybdenum.

[0021] The first substrate 10 may contain a ceramic filler as ceramic particles. Examples of the ceramic filler that can be used include alumina (aluminum oxide), calcium titanate, and magnesium titanate. In particular, the first substrate 10 containing alumina has high rigidity.

[0022] 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.

[0023] 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. A wiring board 1 having such a first substrate 10 has a high degree of freedom in design. Furthermore, by forming the first substrate 10 using a plurality of ceramic layers 11, the first substrate 10 can be manufactured while checking whether the first wiring 30 is properly formed for each layer, thereby improving the yield of the first substrate 10.

[0024] 1 and 2, the first substrate 10 has four ceramic layers 11, but the number of ceramic layers 11 is not limited to four. The number of ceramic layers 11 may be two, three, or five or more.

[0025] <Second Base Material> The second base material 20 is a base material containing 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.

[0026] The organic resin may be, for example, polytetrafluoroethylene (PTFE) or other fluororesins or polyphenylene ether resins. The second substrate 20 may contain components other than the organic resin. In the present disclosure, the organic resin may be, for example, a material that accounts for 30% by mass or more of the material that constitutes the second substrate 20.

[0027] 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.

[0028] The wiring board 1 according to the first embodiment has two second substrates 20. Specifically, one of the two second substrates 20 is bonded to the first surface 101 of the first substrate 10, and the other is bonded to the second surface 102 of the first substrate 10.

[0029] The second substrate 20, located on the first surface 101 of the first substrate 10, has a third surface 103 bonded to the first surface 101 of the first substrate 10, and multiple semiconductor elements 2 are placed on a fourth surface 104 of the second substrate 20 via an intermediate substrate 3 (see Figure 1).

[0030] The second substrate 20 located on the second surface 102 of the first substrate 10 has a third surface 103 joined to the first surface 101 of the first substrate 10, and a fourth surface 104 of the second substrate 20 joined to the motherboard 4 via the joint 7.

[0031] The second base material 20 has a plurality of organic resin layers 21. The plurality of organic resin layers 21 are stacked along the thickness direction of the second base material 20. A wiring board 1 having such a second base material 20 has a high degree of freedom in design. In the example shown in FIG. 2 , the second 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.

[0032] 1 and 2 show an example in which the wiring board 1 has the second base material 20 on each of both main surfaces (first surface 101 and second surface 102) of the first base material 10. However, the wiring board 1 is not limited to this, and it is sufficient that the wiring board 1 has the second base material 20 on at least the first surface 101 of the first base material 10.

[0033] The second substrate 20 containing an organic component is easier to form a fine wiring pattern on than an inorganic substrate. On the other hand, the first substrate 10 made of ceramic has higher rigidity and lower density than the second substrate 20.

[0034] 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.

[0035] The first substrate 10 and the second substrate 20 are bonded together by, for example, hydrogen bonding. Specifically, the first substrate 10 and the second substrate 20 are bonded together by bonding between hydroxyl groups on the first substrate 10 and the second substrate 20. In this case, a ceramic material such as alumina having surface hydroxyl groups may be used for the first substrate 10, and an epoxy resin, which is a resin material containing hydroxyl groups, may be used for the second substrate 20. By directly bonding the first substrate 10 and the second substrate 20 in this way without using solder, underfill, or the like, the thickness of the wiring board 1 can be reduced and the manufacturing process can be simplified.

[0036] The first substrate 10 may contain a glass component, and the second substrate 20 may contain a coupling agent that chemically bonds with the glass component. For example, a silane coupling agent may be used as the coupling agent. Alternatively, a titanium-based coupling agent or an aluminum-based coupling agent may be used as the coupling agent. With this configuration, the first substrate 10 and the second substrate 20 are chemically bonded together, thereby more firmly bonding the first substrate 10 and the second substrate 20, which are made of different materials.

[0037] <First Wiring> The first wiring 30 is a through-hole conductor located in the first substrate 10. Specifically, the first wiring 30 has a through hole 31 that penetrates the first substrate 10, and a conductor 32. The conductor 32 is mainly composed of metal and is located inside the through hole 31.

[0038] The first wiring 30 has land portions 33 on the first surface 101 and the second surface 102 of the first substrate 10 .

[0039] <Second Wiring> The second wiring 40 has a plurality of vias 41 and one or more wiring layers 42. The vias 41 penetrate one or more organic resin layers 21. The wiring layers 42 are located between adjacent organic resin layers 21 and electrically connect the plurality of vias 41 to each other. The second wiring 40 may have a land portion located on the fourth surface 104 of the second base material 20.

[0040] 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.

[0041] 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.

[0042] Of the first wiring 30 and the second wiring 40, only the first wiring 30 may contain a glass component. In this case, the first wiring 30 is firmly bonded to the first base material 10, which also contains a glass component, via the glass component. This allows the rigidity of the first base material 10 to be increased.

[0043] 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.

[0044] 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.

[0045] On the other hand, the second wiring 40 may be formed by copper plating, which allows the first wiring 30 and the second wiring 40 to have a configuration in which only the first wiring 30 contains a glass component.

[0046] The second wiring 40 may be electrically and thermally connected to the semiconductor element 2 via the relay substrate 3. 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.

[0047] Next, the configuration of the second substrate 20 according to the first embodiment will be described with reference to Fig. 3 and Fig. 4. Fig. 3 is a schematic cross-sectional view showing the configuration of the second substrate 20 according to the first embodiment. Fig. 4 is a schematic cross-sectional view showing the configurations of the first substrate 10 and the second substrate 20 according to the first embodiment.

[0048] As described above, the second base material 20 has a plurality of organic resin layers 21. Specifically, the plurality of organic resin layers 21 have a first layer 21a that is in contact with the first base material 10, and second layers 21b to 21d that are laminated on the first layer 21a. In other words, the second layers 21b to 21d refer to all of the plurality of organic resin layers 21 that are not in contact with the first base material 10. The second layers 21b to 21d are formed by laminating a first organic resin layer 21b, a second organic resin layer 21c, and a third organic resin layer 21d in this order.

[0049] 3, the second substrate 20, i.e., the first layer 21a and the second layers 21b to 21d, contain inorganic particles 15. The inorganic particles 15 are, for example, silica. The inorganic particles 15 are not limited to silica, and may be alumina, magnesium oxide, zirconia, calcium oxide, calcium carbonate, or the like.

[0050] The inorganic particles 15 have the effect of reducing the thermal expansion coefficient of the second substrate 20, which is made of an organic resin and has a relatively high thermal expansion coefficient. However, if the inorganic particles 15 are located at the interface between the first substrate 10 and the second substrate 20, the contact area between the first substrate 10 and the second substrate 20 will be reduced, which may reduce the adhesion between the first substrate 10 and the second substrate 20.

[0051] Therefore, in the wiring board 1 according to the first embodiment, the content of inorganic particles 15 in the first layer 21a is relatively low. Specifically, as shown in Fig. 3, the content of inorganic particles 15 in the first layer 21a of the second base material 20 is lower than the content of inorganic particles 15 in the second layers 21b to 21d. In other words, the content of inorganic particles 15 in the second layers 21b to 21d of the second base material 20 is higher than the content of inorganic particles 15 in the first layer 21a.

[0052] With this configuration, compared to conventional wiring boards, it is possible to reduce the amount of inorganic particles 15 located at the interface between the first substrate 10 and the second substrate 20. Therefore, with the wiring board 1 according to the first embodiment, it is possible to increase the adhesive strength between the first substrate 10 and the second substrate 20 while reducing the thermal expansion coefficient of the second substrate 20 made of organic resin by the inorganic particles 15.

[0053] The first layer 21a and the second layers 21b to 21d having different contents of inorganic particles 15 can be formed, for example, by adjusting the amount of inorganic particles 15 contained in the organic resin sheet that is the material for the organic resin layer 21 during the manufacturing process of the second substrate 20.

[0054] The content of the inorganic particles 15 in the second layers 21b to 21d is preferably 40 wt % or more and 80 wt % or less, and the average particle size of the inorganic particles 15 in the second layers 21b to 21d is preferably 0.1 μm or more and 0.5 μm or less.

[0055] Furthermore, the maximum particle size of the inorganic particles 15 in the second layers 21b to 21d is preferably 10 times or less the average particle size. For example, when the average particle size of the inorganic particles 15 in the second layers 21b to 21d is 0.1 μm, the maximum particle size is preferably 1 μm or less, and when the average particle size is 0.5 μm, the maximum particle size is preferably 5 μm or less.

[0056] The wiring board 1 according to the first embodiment may further include a third wiring 50. The third wiring 50 is located on the second layers 21b to 21d. The third wiring 50 includes a first ground wiring 51, a second ground wiring 52, and a signal line 53.

[0057] Specifically, the first ground wiring 51 is located in the first organic resin layer 21b and is connected to the ground. The second ground wiring 52 is located in the third organic resin layer 21d and is connected to the ground. The signal line 53 is located in the second organic resin layer 21c and faces the first ground wiring 51 and the second ground wiring 52. The first ground wiring 51 and the second ground wiring 52 are so-called solid patterns and have a larger horizontal width (wiring width) than the signal line 53.

[0058] The second base material 20 containing inorganic particles 15 has a smaller dielectric loss than a second base material that does not contain inorganic particles. That is, the inorganic particles 15 have the effect of improving the electrical characteristics of the second base material. Therefore, by positioning the third wiring 50 in the second layers 21b to 21d, which have a relatively high content of inorganic particles 15, a wiring board with excellent electrical characteristics can be obtained.

[0059] Furthermore, when the wiring has a stripline (a configuration in which the front and back of the signal line are sandwiched between ground surfaces via an insulating layer), the electrical characteristics of the stripline (the propagation speed of the electrical signal in the signal line) can be improved by relatively increasing the content of inorganic particles 15 in the first organic resin layer 21b in which the first ground wiring 51 is located, the second organic resin layer 21c in which the signal line 53 is located, and the third organic resin layer 21d in which the second ground wiring 52 is located.

[0060] 3, the average particle size of the inorganic particles 15a contained in the first layer 21a may be equal to or larger than the average particle size of the inorganic particles 15b contained in the second layers 21b to 21d. Also, the average particle size of the inorganic particles 15a contained in the first layer 21a may be larger than the average particle size of the inorganic particles 15b contained in the second layers 21b to 21d.

[0061] For example, when comparing the contact area between the first substrate 10 and the second substrate 20 (first layer 21a) between two first layers having the same inorganic particle content (mass percent), one containing inorganic particles with a relatively small average particle size and the other containing inorganic particles with a relatively large average particle size, the first layer containing inorganic particles with a relatively small average particle size has a larger contact area with the first substrate 10. In other words, the first layer containing inorganic particles with a relatively small average particle size has a lower adhesion strength with the first substrate 10. Therefore, in the wiring board 1 according to the first embodiment, the average particle size of the inorganic particles 15a contained in the first layer 21a is set to be larger than the average particle size of the inorganic particles 15b contained in the second layers 21b to 21d. This increases the adhesion strength between the first layer 21a and the first substrate 10 compared to when the average particle size of the inorganic particles 15 contained in the first layer 21a is the same as the average particle size of the inorganic particles 15b contained in the second layers 21b to 21d.

[0062] On the other hand, the inorganic particles 15b contained in the second layers 21b to 21d have a relatively small average particle size, which makes it easy to achieve finer wiring, and is therefore suitable for positioning the third wiring 50.

[0063] 4, the wiring board 1 according to the first embodiment has two second base materials 20. One of the two second base materials 20 is bonded to the first surface 101 of the first base material 10, and the other is bonded to the second surface 102 of the first base material 10. The two second base materials 20 each include third wiring 50 located in the second layers 21b to 21d.

[0064] In this case, the third wiring 50 located on the second substrate 20 bonded to the first surface 101 of the first substrate 10 and the third wiring 50 located on the second substrate 20 bonded to the second surface 102 are electrically connected via the conductor 32 that penetrates the first substrate 10. This allows the third wiring 50 to be arranged at a high density.

[0065] Next, the configuration of the first layer 21a and its surroundings according to the first embodiment will be described with reference to Fig. 5. Fig. 5 is a schematic cross-sectional view showing the configuration of the first layer 21a and its surroundings according to the first embodiment.

[0066] 5, when the first layer 21a is virtually divided into two regions R1 and R2 aligned in the thickness direction, the content of inorganic particles 15 in the region R1 that contacts the first base material 10 may be lower than the content of inorganic particles 15 in the region R2 that contacts the second layer 21b. This can further increase the adhesion strength between the first base material 10 and the first layer 21a.

[0067] A method for relatively reducing the content of inorganic particles 15 in region R1 includes, for example, etching region R1 of the organic resin sheet that will be the material for organic resin layer 21 with fluoronitric acid in the manufacturing process of second base material 20. This melts inorganic particles 15 contained in region R1 of the organic resin sheet, thereby reducing the content of inorganic particles 15 in region R1.

[0068] As described above, the wiring board 1 according to the first embodiment has a relatively low content of inorganic particles 15 in the first layer 21 a. This configuration makes it possible to reduce the amount of inorganic particles 15 located at the interface between the first substrate 10 and the second substrate 20 compared to conventional wiring boards. Therefore, the wiring board 1 according to the first embodiment can increase the adhesive strength between the first substrate 10 and the second substrate 20 while reducing the thermal expansion coefficient of the second substrate 20 made of organic resin by the inorganic particles.

[0069] Second Embodiment Figure 6 is a schematic cross-sectional view showing the configuration of a second base material 20 according to a second embodiment. The thickness of the first layer 21a of the second base material 20 may be equal to or less than the thickness of the organic resin layers of the second layers 21b to 21d. Furthermore, the thickness of the first layer 21a of the second base material 20 may be thinner than the thickness of the organic resin layers of the second layers 21b to 21d. In the example shown in Figure 6, the thickness S1 of the first layer 21a is thinner than the thickness S2 of the first organic resin layer 21b. Similarly, the first layer 21a is thinner than the second organic resin layer 21c and the third organic resin layer 21d.

[0070] The first layer 21a, which has a relatively low content of inorganic particles 15, has a higher coefficient of thermal expansion than the second layer 21b, which has a relatively high content of inorganic particles 15. In contrast, by making the thickness of the first layer 21a equal to or smaller than the thickness of the second layer 21b, it is possible to reduce the influence of thermal expansion of the first layer 21a as much as possible while improving the adhesion between the first substrate 10 and the second substrate 20 by the first layer 21a.

[0071] The present technology may also be configured as follows. (1) A wiring board (for example, wiring board 1) includes a first substrate (for example, first substrate 10), a second substrate (for example, second substrate 20) made of an organic resin and bonded to the first substrate, the second substrate containing a plurality of inorganic particles (for example, inorganic particles 15), and wiring (for example, third wiring 50) located on the second substrate. The first substrate has higher rigidity than the second substrate. The second substrate includes a first layer (for example, first layer 21a) having a relatively low content of inorganic particles and a second layer (for example, second layers 21b to 21d) laminated on the first layer and having a relatively high content of inorganic particles. The first layer is in contact with the first substrate. (2) In the wiring board described in (1) above, the wiring may include a signal line (for example, signal line 53), and the signal line may be located on a second layer of the second substrate. (3) In the wiring board described in (1) above, the second layer may have a structure in which a first organic resin layer (for example, first organic resin layer 21 b), a second organic resin layer (for example, second organic resin layer 21 c), and a third organic resin layer (for example, third organic resin layer 21 d) are stacked in this order, the wiring may include a first ground wiring (for example, first ground wiring 51) located in the first organic resin layer and connected to ground, and a second ground wiring (for example, second ground wiring 52) located in the third organic resin layer and connected to ground, and the signal line may be located in the second organic resin layer and face the first ground wiring and the second ground wiring. (4) In the wiring board described in (1) above, the second layer may have a plurality of organic resin layers, and the thickness of the first layer may be equal to or less than the thickness of the organic resin layers in the second layer. (5) In the wiring board according to any one of (1) to (4) above, the average particle size of the inorganic particles contained in the first layer may be equal to or larger than the average particle size of the inorganic particles contained in the second layer. (6) In the wiring board according to any one of (1) to (5) above, the first base material may be made of ceramic. (7) In the wiring board according to any one of (1) to (6) above, the first base material may have a plurality of ceramic layers.(8) The wiring board according to any one of (1) to (7) above may have two second substrates, and the first substrate may have a first surface (for example, first surface 101) and a second surface (for example, second surface 102) located opposite the first surface, and the second substrate may be bonded to each of the first surface and the second surface. (9) The wiring board according to (8) above may have a conductor (for example, conductor 32) penetrating the first surface and the second surface of the first substrate, and wiring located on the second substrate bonded to the first surface and wiring located on the second substrate bonded to the second surface may be electrically connected via the conductor. (10) In the wiring board according to any one of (1) to (9) above, the first substrate may contain a glass component, and the first layer of the second substrate may contain a coupling agent that chemically bonds with the glass component. (11) In the wiring board according to any one of (1) to (10) above, when the first layer is virtually divided into two regions aligned in the thickness direction, the inorganic particle content in the region of the two regions that contacts the first substrate may be lower than the inorganic particle content in the region of the two regions that contacts the second layer. (12) In the wiring board according to any one of (1) to (11) above, the inorganic particle content in the second layer may be 40 wt % to 80 wt %, the average particle size may be 0.1 μm to 0.5 μm, and the maximum particle size may be equal to or less than 10 times the average particle size. (13) A semiconductor device (for example, semiconductor device 100) may have the wiring board according to any one of (1) to (12) above and a semiconductor element (for example, semiconductor element 2) mounted on the second substrate of the wiring board.

[0072] 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.

[0073] REFERENCE SIGNS LIST 1 wiring substrate 2 semiconductor element 3 relay substrate 10 first base material 11 ceramic layer 15 inorganic particles 20 second base material 21 organic resin layer 21a first layer 21b to 21d second layer 30 first wiring 31 through hole 32 conductor 40 second wiring 50 third wiring 100 semiconductor device

Claims

1. A wiring board comprising: a first substrate; a second substrate made of an organic resin containing a plurality of inorganic particles and bonded to the first substrate; and wiring located on the second substrate, wherein the first substrate has a higher rigidity than the second substrate; the second substrate comprises: a first layer having a relatively low content of the inorganic particles; and a second layer laminated on the first layer and having a relatively high content of the inorganic particles; and the first layer is in contact with the first substrate.

2. The wiring board according to claim 1, wherein the wiring includes a signal line, the signal line being located on the second layer of the second base material.

3. The wiring board according to claim 2, wherein the second layer has a structure in which a first organic resin layer, a second organic resin layer and a third organic resin layer are laminated in this order, the wiring includes a first ground wiring located in the first organic resin layer and connected to ground, and a second ground wiring located in the third organic resin layer and connected to ground, and the signal line is located in the second organic resin layer and faces the first ground wiring and the second ground wiring.

4. The wiring board according to claim 1, wherein the second layer has a plurality of organic resin layers, and the thickness of the first layer is equal to or less than the thickness of the organic resin layers of the second layer.

5. A wiring board according to any one of claims 1 to 4, wherein the average particle size of the inorganic particles contained in the first layer is equal to or greater than the average particle size of the inorganic particles contained in the second layer.

6. The wiring board according to any one of claims 1 to 5, wherein the first base material is made of ceramic.

7. The wiring board according to claim 6, wherein the first base material has a plurality of ceramic layers.

8. A wiring board as described in claim 6 or 7, comprising two second substrates, each of the first substrates having a first surface and a second surface located opposite the first surface, and the second substrates being bonded to each of the first surface and the second surface.

9. The wiring board described in claim 8, further comprising a conductor penetrating the first surface and the second surface of the first substrate, wherein the wiring located on the second substrate bonded to the first surface and the wiring located on the second substrate bonded to the second surface are electrically connected via the conductor.

10. A wiring board according to any one of claims 6 to 9, wherein the first base material contains a glass component, and the first layer of the second base material contains a coupling agent that chemically bonds with the glass component.

11. A wiring board described in any one of claims 1 to 10, wherein when the first layer is virtually divided into two regions aligned in the thickness direction, the content of the inorganic particles in the region of the two regions that comes into contact with the first base material is lower than the content of the inorganic particles in the region of the two regions that comes into contact with the second layer.

12. A wiring board described in any one of claims 1 to 11, wherein the content of the inorganic particles in the second layer is 40 wt % or more and 80 wt % or less, the average particle size is 0.1 μm or more and 0.5 μm or less, and the maximum particle size is 10 times the average particle size or less.

13. A semiconductor device comprising: a wiring board according to any one of claims 1 to 12; and a semiconductor element mounted on the second base material of the wiring board.

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