Composite wiring board and electronic module

Abstract

This composite wiring board comprises a core layer, a first resin layer, and a second resin layer. The core layer has a first surface, a second surface positioned on the opposite side from the first surface, and a side surface section connecting the first surface and the second surface. The core layer contains a ceramic material. The first resin layer is in contact with the first surface and contains a first resin material. The second resin layer is in contact with the second surface and contains a second resin material. The first resin layer and the second resin layer each cover a portion of the side surface section. The side surface section has a portion which is exposed from the first resin layer and the second resin layer.

Description

Composite Wiring Substrate and Electronic Module

[0001] The present disclosure relates to a composite wiring substrate and an electronic module.

[0002] A composite wiring substrate including a core layer mainly composed of a ceramic material and a resin layer mainly composed of a resin material, with the resin layers positioned on both sides of the core layer, is known (see Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2007-324419

[0004] The composite wiring substrate of the present disclosure has a core layer, a first resin layer, and a second resin layer. The core layer has a first surface, a second surface located opposite to the first surface, and side portions connecting the first surface and the second surface, and includes a ceramic material. The first resin layer contacts the first surface and includes a first resin material. The second resin layer contacts the second surface and includes a second resin material. The first resin layer and the second resin layer each cover a part of the side portions. The side portions have portions exposed from the first resin layer and the second resin layer.

[0005] FIG. 1 is a perspective view showing an example of the configuration of a composite wiring substrate according to an embodiment. FIG. 2 is an exploded perspective view showing an example of the configuration of a composite wiring substrate according to an embodiment. FIG. 3 is a cross-sectional view of one end portion taken along the line A-A shown in FIG. 1. FIG. 4 is a cross-sectional view showing an example of the configuration of a composite wiring substrate in which the length of the side portion covered by the first resin layer is different from the length of the side portion covered by the second resin layer. FIG. 5 is a cross-sectional view showing an example of the configuration of a composite wiring substrate in which the thickness of the first resin layer is different from the thickness of the second resin layer. FIG. 6 is a cross-sectional view showing an example of the configuration of a composite wiring substrate having regions where the first surface and the second surface are exposed. FIG. 7 is an enlarged perspective view showing an example of the configuration of a composite wiring substrate in which a part of a conductor is exposed from the side portion. FIG. 8 is a cross-sectional view showing an example of the configuration of a composite wiring substrate in which a part of a conductor is exposed from the side portion. FIG. 9 is a cross-sectional view showing an example of the configuration of a composite wiring substrate in which the pitch between the first electrodes is smaller than the pitch between the second electrodes. FIG. 10 is a cross-sectional view showing an example of the configuration of an electronic module according to an embodiment.

[0006] The embodiments for implementing the composite wiring board and electronic module according to this disclosure (hereinafter referred to as "embodiments") will be described in detail below with reference to the drawings. However, this disclosure is not limited by these embodiments. Furthermore, each embodiment can be combined as appropriate, provided that the processing content is not inconsistent. Also, the same parts are denoted by the same reference numerals in each of the following embodiments, and redundant descriptions are omitted.

[0007] Furthermore, in the drawings referenced below, for the sake of clarity, mutually orthogonal X-axis, Y-axis, and Z-axis directions are defined, and a Cartesian coordinate system is shown in which the Z-axis direction is the thickness direction of the composite wiring board. Also, in this disclosure, a plan view means a plan view taken from a direction perpendicular to the first surface 11 of the composite wiring board 100. Also, in this disclosure, the horizontal direction means the XY plane direction.

[0008] In the conventional technology described above, there is a need to improve the bonding strength between the core layer and the resin layer while reducing the possibility of the composite wiring board warping due to the heat generated in the composite wiring board by the mounted electronic elements and the operation of said electronic elements, as well as heat received from external sources other than the electronic elements.

[0009] This disclosure provides a technology that can improve the bonding strength between the core layer and the resin layer while reducing the possibility of the composite wiring board warping due to heat generated in the composite wiring board by the mounted electronic elements and the operation of said electronic elements, as well as heat received from external sources other than the electronic elements.

[0010] <Embodiment> Figure 1 is a perspective view showing an example of the configuration of a composite wiring board 100 according to an embodiment. Figure 2 is an exploded perspective view showing an example of the configuration of a composite wiring board 100 according to an embodiment.

[0011] As shown in Figures 1 and 2, the composite wiring board 100 according to the embodiment comprises a core layer 10, a first resin layer 20, and a second resin layer 30. The composite wiring board 100 is a laminate of the core layer 10, the first resin layer 20, and the second resin layer 30. In plan view, the composite wiring board 100 may be a polygon, including a rectangle, or it may have a curved surface on a part of its outer edge.

[0012] The core layer 10 contains a ceramic material. The first resin layer 20 contains a first resin material. The second resin layer 30 contains a second resin material. The detailed configurations of the core layer 10, the first resin layer 20, and the second resin layer 30 will be described later with reference to Figures 3 to 9.

[0013] Ceramic materials have higher rigidity compared to resin materials. Therefore, a composite wiring board 100 composed of a core layer 10 containing ceramic material and a first resin layer 20 and a second resin layer 30 containing resin material can have improved rigidity compared to a composite wiring board composed solely of resin material. As a result, even if the composite wiring board 100 is made thinner, it is easy to improve its rigidity without adding reinforcing members or the like.

[0014] Figure 3 is a cross-sectional view of one end in the direction of line A-A shown in Figure 1. Note that Figure 3 shows the outer edge end of the composite wiring board 100 according to the embodiment. Figure 4 is a cross-sectional view showing an example of the configuration of a composite wiring board 100 in which the length L1 of the side portion 13 covered by the first resin layer 20 and the length L2 of the side portion 13 covered by the second resin layer 30 are different. Figure 5 is a cross-sectional view showing an example of the configuration of a composite wiring board 100 in which the thickness T1 of the first resin layer 20 and the thickness T2 of the second resin layer 30 are different. Figure 6 is a cross-sectional view showing an example of the configuration of a composite wiring board 100 having regions R1 and R2 in which the first surface 11 and the second surface 12 are exposed. Note that in Figure 6, the inclined surfaces 16 and 17 are omitted. Figure 7 is an enlarged perspective view showing an example of the configuration of a composite wiring board 100 in which a part of the conductor is exposed from the side portion 13. Figure 8 is a cross-sectional view showing an example of the configuration of a composite wiring board 100 in which a part of the conductor is exposed from the side portion 13. Figure 9 is a cross-sectional view showing an example of the configuration of a composite wiring board 100 in which the pitch between the first electrodes 91 is smaller than the pitch between the second electrodes 92.

[0015] <Core Layer> The core layer 10 contains ceramic. As the ceramic, for example, ceramics mainly composed of at least one selected from the group consisting of aluminum oxide, silicon oxide, zirconium oxide, silicon carbide, silicon nitride, and aluminum nitride, or ceramics mainly composed of composite oxides such as mullite, zircon, steatite, enstatite, glass ceramics, and glass can be used. The core layer 10 may also contain glass components in addition to ceramic. In this disclosure, the main component is defined as a material that accounts for 50% by mass or more of the material.

[0016] As shown in Figure 3, the core layer 10 has a first surface 11 and a second surface 12 located opposite the first surface 11. The core layer 10 may be a plate-like body with the first surface 11 and the second surface 12 as its main surfaces. The core layer 10 also has a side portion 13 connecting the first surface 11 and the second surface 12. The side portion 13 becomes the outer surface of the core layer 10.

[0017] Furthermore, the core layer 10 may have a plurality of ceramic layers 14. In this case, the plurality of ceramic layers 14 may be stacked along the thickness direction (Z-axis direction) of the core layer 10. By constructing the core layer 10 using a plurality of ceramic layers 14 in this way, a core layer 10 having a wiring layer 42, which will be described later, inside can be obtained.

[0018] A composite wiring board 100 having such a core layer 10 offers greater design flexibility compared to one without a core layer 10. Furthermore, by constructing the core layer 10 using multiple ceramic layers 14, the core layer 10 can be manufactured while checking layer by layer whether the first conductor 40, described later, is properly formed. As a result, disconnections and short circuits of the first conductor 40 can be detected and corrected early in the manufacturing process, improving the yield of the core layer 10.

[0019] In the example shown in Figure 3, the core layer 10 has three ceramic layers 14, but the number of ceramic layers 14 is not limited to three. The number of ceramic layers 14 may be two, or four or more. Furthermore, the core layer 10 does not necessarily have a multilayer structure. That is, the core layer 10 may be a single layer.

[0020] In the core layer 10, the side portion 13 may have a main side portion 15, a first inclined surface 16, and a second inclined surface 17. The main side portion 15 is located in the center of the core layer 10 in the thickness direction. The first inclined surface 16 connects to the main side portion 15 and the first surface 11. The first inclined surface 16 is an inclined surface that slopes inward horizontally as it approaches the first surface 11. Here, "inward horizontally" refers to the direction toward the center of the composite wiring board 100. The second inclined surface 17 connects to the main side portion 15 and the second surface 12. The second inclined surface 17 is an inclined surface that slopes inward horizontally as it approaches the second surface 12. The main side portion 15 may be a vertical surface.

[0021] <First Resin Layer> The first resin layer 20 includes a first resin material, as described above. The first resin material may be an organic resin. The organic resin may be, for example, an epoxy resin, an acrylic resin, a polycarbonate resin, a polyimide resin, an olefin resin, or a polyphenylene resin.

[0022] Furthermore, the organic resin may be, for example, polytetrafluoroethylene (PTFE), other fluororesins, or polyphenylene ether resins. The first resin layer 20 may also contain components other than the organic resin. For example, the first resin layer 20 may contain silica or rubber material in addition to the first resin material. Also, the main component of the first resin layer 20 does not necessarily have to be the first resin material. That is, for example, silica may account for 50% or more by mass of the first resin layer 20, and the material with the next highest mass percentage may be the first resin material.

[0023] As shown in Figure 3, the first resin layer 20 may have a third surface 21 and a fourth surface 22 located opposite the third surface 21. The first resin layer 20 may be a plate-like body with the third surface 21 and the fourth surface 22 as its main surfaces. The first resin layer 20 may also have a first side surface 23 connecting the third surface 21 and the fourth surface 22. The first side surface 23 becomes the outer surface of the first resin layer 20.

[0024] The first resin layer 20 may be superimposed on the first surface 11 of the core layer 10 and may cover the entire surface 11. The third surface 21 of the first resin layer 20 is in contact with the first surface 11 of the core layer 10. In other words, the first resin layer 20 is directly bonded to the core layer 10 without an adhesive layer in between.

[0025] Thus, because there is no adhesive layer to bond the core layer 10 and the first resin layer 20, the thickness of the composite wiring board 100 is reduced, making it possible to reduce the height of the composite wiring board 100.

[0026] Specifically, the ceramic layer 14 of the core layer 10 may contain a ceramic material with hydroxyl groups on its surface. In this case, the first resin layer 20 may be bonded to the core layer 10 by intermolecular forces due to the hydroxyl groups. This allows the core layer 10 and the first resin layer 20 to be hydrogen-bonded by the hydroxyl groups. Therefore, the term "contact" above includes a state in which hydrogen bonds are formed between the constituent molecules of the core layer 10 and the first resin layer 20 by hydroxyl groups.

[0027] The first resin layer 20 may have a plurality of organic resin layers 24. The plurality of organic resin layers 24 may be laminated along the thickness direction of the first resin layer 20. By constructing the first resin layer 20 using a plurality of organic resin layers 24, a first resin layer 20 having a wiring layer described later inside can be obtained. A composite wiring board 100 having such a first resin layer 20 offers greater design freedom compared to a case where there is no first resin layer 20 or where the organic resin layer 24 is a single layer.

[0028] In the example shown in Figure 3, the first resin layer 20 has three organic resin layers 24, but the number of organic resin layers 24 is not limited to three. The number of organic resin layers 24 may be two or less, or four or more.

[0029] The first resin layer 20 covers a portion of the side surface 13. Specifically, the first resin layer 20 may cover at least a portion of the first inclined surface 16. As shown in Figure 3, the first resin layer 20 may cover the entire surface of the first inclined surface 16.

[0030] <Second Resin Layer> The second resin layer 30 includes the second resin material as described above. The second resin material may be an organic resin. The organic resin may be, for example, an epoxy resin, an acrylic resin, a polycarbonate resin, a polyimide resin, an olefin resin, or a polyphenylene resin.

[0031] Furthermore, the organic resin may be, for example, polytetrafluoroethylene (PTFE), other fluororesins, or polyphenylene ether resins. The second resin layer 30 may also contain components other than the organic resin. For example, the second resin layer 30 may contain silica or rubber material in addition to the second resin material. Also, the main component of the second resin layer 30 does not necessarily have to be the second resin material. That is, for example, silica may account for 50% or more by mass of the second resin layer 30, and the material with the next highest mass percentage may be the second resin material.

[0032] As shown in Figure 3, the second resin layer 30 may have a fifth surface 31 and a sixth surface 32 located opposite the fifth surface 31. The second resin layer 30 may be a plate-like body with the fifth surface 31 and the sixth surface 32 as its main surfaces. The second resin layer 30 may also have a second side surface 33 connecting the fifth surface 31 and the sixth surface 32. The second side surface 33 becomes the outer surface of the second resin layer 30.

[0033] The second resin layer 30 may be superimposed on the second surface 12 of the core layer 10 and may cover the entire surface 12. The fifth surface 31 of the second resin layer 30 is in contact with the second surface 12 of the core layer 10. In other words, the second resin layer 30 is directly bonded to the core layer 10 without an adhesive layer in between.

[0034] Thus, because there is no adhesive layer to bond the core layer 10 and the second resin layer 30, the thickness of the composite wiring board 100 is reduced, making it possible to reduce the height of the composite wiring board 100.

[0035] Specifically, the ceramic layer 14 of the core layer 10 may mainly contain a ceramic material with hydroxyl groups on its surface. In this case, the second resin layer 30 may be bonded to the core layer 10 by intermolecular forces due to the hydroxyl groups. This allows the core layer 10 and the second resin layer 30 to be hydrogen-bonded by the hydroxyl groups. Therefore, the term "contact" above includes a state in which hydrogen bonds are formed between the constituent molecules of the core layer 10 and the second resin layer 30 by hydroxyl groups.

[0036] The second resin layer 30 may have a plurality of organic resin layers 34. The plurality of organic resin layers 34 may be laminated along the thickness direction of the second resin layer 30. By constructing the second resin layer 30 using a plurality of organic resin layers 34, a second resin layer 30 having a wiring layer described later inside can be obtained. A composite wiring board 100 having such a second resin layer 30 offers greater design freedom compared to a case without the second resin layer 30.

[0037] In the example shown in Figure 3, the second resin layer 30 has three organic resin layers 34, but the number of organic resin layers 34 is not limited to three. The number of organic resin layers 34 may be two or less, or four or more.

[0038] The second resin layer 30 covers a portion of the side surface 13. Specifically, the second resin layer 30 may cover at least a portion of the second inclined surface 17. As shown in Figure 3, the second resin layer 30 may cover the entire second inclined surface 17.

[0039] The side portion 13 has a portion exposed from the first resin layer 20 and the second resin layer 30. As shown in Figure 3, the portion exposed from the first resin layer 20 and the second resin layer 30 may be the main side portion 15.

[0040] The first resin layer 20 and the second resin layer 30, which contain resin material, offer greater flexibility in the wiring formation process compared to substrates containing only inorganic materials, making it easier to form fine wiring patterns. On the other hand, the core layer 10, which contains ceramic material, has higher rigidity than the first resin layer 20 and the second resin layer 30. Furthermore, the core layer 10, which contains ceramic material, has a higher density than the first resin layer 20 and the second resin layer 30.

[0041] The composite wiring board 100, by combining the core layer 10, the first resin layer 20, and the second resin layer 30, can achieve miniaturization and narrow pitch of wiring while increasing rigidity. As the size of the substrate increases, the substrate becomes more prone to warping, so the configuration of the composite wiring board 100, in which the core layer 10 compensates for the low rigidity of the first resin layer 20 and the second resin layer 30, is particularly useful when increasing the size of the substrate. In this disclosure, "warping" can be confirmed, for example, by measuring the flatness of the composite wiring board 100.

[0042] Furthermore, by positioning resin layers 20 and 30 on both sides of the core layer 10, the amount of deformation in response to temperature changes, such as thermal strain on both sides of the core layer 10 caused by the heat of the mounted electronic elements 210 (see Figures 6 and 10), the heat generated in the composite wiring board 100 by the driving of the electronic elements 210, and heat received from external sources other than the electronic elements 210, can be made closer to that of the case where resin layers 20 and 30 are positioned on only one side of the core layer 10.Therefore, the warping of the composite wiring board 100 due to the heat of the electronic elements 210 can be reduced.In addition, since a portion of the side surface of the core layer 10 is covered by resin layers 20 and 30 on both sides, the bonding area between the core layer 10 and the resin layers 20 and 30 is increased, and even if the composite wiring board 100 warps due to the heat of the electronic elements 210, the possibility of the composite wiring board 100 peeling off and being damaged at the interface between the core layer 10 and the first surface 11 or second surface 12 of the resin layers 20 and 30 can be reduced.

[0043] Furthermore, when electrodes are located on the surface of the composite wiring board 100 and the surface of the electrodes is covered with plating, the possibility of the plating solution entering the boundary portion 13 of the side portion between the core layer 10 and the resin layers 20, 30, or the possibility of the plating solution remaining, can be reduced. In particular, when a metal film is covered on the electrodes by electroless plating, the possibility of gold or other metals adhering to areas where the plating solution remains can be reduced.

[0044] Further, when there is a gap due to peeling at the boundary between the core layer 10 and the resin layers 20 and 30 on the side surface of the composite wiring board 100, there is a possibility that foreign matter may enter the gap during the process of mounting elements, components, etc. on the composite wiring board 100 or the process of bonding the composite wiring board 100 to a printed board. If the foreign matter that has entered has conductivity, there is a possibility of a short circuit occurring between the wirings of the composite wiring board 100. However, since the resin layers 20 and 30 are located on a part of the side surface of the core layer 10, the above possibility can be reduced.

[0045] Further, since the portions of the side surface portion 13 where the resin layers 20 and 30 are located are inclined surfaces, the bonding area between the core layer 10 and the resin layers 20 and 30 increases compared to the case where the entire side surface portion 13 is a vertical surface. Therefore, the bonding strength between the core layer 10 and the resin layers 20 and 30 can be improved.

[0046] Also, the first resin material contained in the first resin layer 20 and the second resin material contained in the second resin layer 30 may be the same material. More specifically, the first resin layer 20 and the second resin layer 30 may be made of the same material.

[0047] As a result, it becomes easier to make the amount of deformation on both sides of the composite wiring board 100 due to the heat generated by the electronic element 210 or the heat generated by the electronic element 210 closer. Therefore, the warping of the composite wiring board 100 due to the heat of the electronic element 210 can be reduced. Also, compared to the case where different materials are used for the first resin material and the second resin material, the manufacturing of the composite wiring board 100 becomes easier and the manufacturing cost can be reduced.

[0048] Also, the thermal conductivity of the ceramic material contained in the core layer 10 may be higher than the thermal conductivity of the first resin material contained in the first resin layer 20 and the thermal conductivity of the second resin material contained in the second resin layer 30.

[0049] As a result, by partially exposing the entire side surface of the core layer 10 with high thermal conductivity without being covered by the resin layers 20 and 30, the heat generated in the composite wiring board 100 or the heat generated by the electronic element 210 can be efficiently dissipated.

[0050] As shown in Figure 4, in a cross-sectional view, the length L1 of the side portion 13 covered by the first resin layer 20 and the length L2 of the side portion 13 covered by the second resin layer 30 may be different. For example, the length L1 of the side portion 13 covered by the first resin layer 20 may be longer than the length L2 of the side portion 13 covered by the second resin layer 30. The relative lengths of the length L1 of the side portion 13 covered by the first resin layer 20 and the length L2 of the side portion 13 covered by the second resin layer 30 may be the same as the relative lengths of the first inclined surface 16 and the second inclined surface 17 in the thickness direction of the core layer 10. Note that the length L1 of the side portion 13 covered by the first resin layer 20 is the length in the thickness direction from the first surface 11 of the core layer 10 to the tip of the first resin layer 20 located on the side portion 13. Furthermore, the length L2 of the side portion 13 covered by the second resin layer 30 is the length in the thickness direction from the second surface 12 of the core layer 10 to the tip of the second resin layer 30 located on the side portion 13. As shown in Figure 4, the first inclined surface 16 and the second inclined surface 17 may each be located on the side of only one ceramic layer 14, or at least one of the inclined surfaces may be located across the side of multiple ceramic layers 14.

[0051] This allows control over the exposed position and range of the side portion 13, thereby controlling the position and range of heat dissipation from the side portion 13, and thus controlling the temperature conditions of the first resin layer 20 and the second resin layer 30. As a result, the temperature distribution in the composite wiring board 100 can be set to the optimal conditions for reducing warping.

[0052] As shown in Figure 5, the thickness T1 of the first resin layer 20 and the thickness T2 of the second resin layer 30 may be different. Specifically, the first resin layer 20 may have an electronic element mounting region M1 on which an electronic element 210 is mounted. The thickness T1 of the first resin layer 20 may be greater than the thickness T2 of the second resin layer 30. The number of organic resin layers 24 constituting the first resin layer 20 may be greater than the number of organic resin layers 34 constituting the second resin layer 30.

[0053] In this way, the heat capacity of the first resin layer 20 can be increased by making the resin layer on the side on which the electronic element 210 is mounted thicker. This reduces the possibility of the composite wiring board 100 warping when the heat on the side on which the electronic element 210 is mounted is greater than that on the opposite side. Furthermore, the electronic element 210 in this disclosure may be a diode, transistor, light-emitting element, light-receiving element, sensor element, integrated circuit (IC), resistor, capacitor, or inductor, or a combination thereof.

[0054] As shown in Figure 6, the first surface 11 may have a region R1 exposed from the first resin layer 20. For example, the region R1 exposed from the first resin layer 20 may be located in the center of the first surface 11 in a plan view, and may be a polygon including a rectangle, or may have a curved surface on part of its outer edge.

[0055] By dissipating heat from the exposed region R1, heat generated by the electronic element 210, heat generated in the composite wiring board 100 by the driving of the electronic element 210, and heat received from external sources other than the electronic element 210 can be efficiently dissipated.

[0056] Furthermore, by efficiently transferring the heat generated by the electronic element 210, or the heat received by the electronic element 210 from the outside, to the region R1 where the first surface 11 is exposed, without passing through the first resin layer 20, the amount of heat moving from the composite wiring board 100 to the side portion 13 is increased, and as a result, the temperature of the electronic element 210 can be reduced.

[0057] Furthermore, the first surface 11 may have an electronic element mounting region M1 in the region R1 exposed from the first resin layer 20, on which the electronic element 210 is mounted.

[0058] This allows heat from the heat source electronic element 210 to be efficiently transferred to the side portion 13. As a result, heat dissipation of the composite wiring board 100 can be performed more efficiently. Therefore, the need for control to reduce heat generation from the electronic element 210 and heat transfer to the electronic element 210, as well as the need to limit power for heat suppression, can be reduced. In addition, since the need for a separate cooling means is reduced, the entire device including the composite wiring board 100 can be miniaturized.

[0059] Furthermore, by efficiently transferring the heat generated in the electronic element 210, or the heat transferred to the electronic element 210 from the outside, to the region R1 where the first surface 11 is exposed, without going through the first resin layer 20, the amount of heat moving from the composite wiring board 100 to the side portion 13 is increased, and as a result, the temperature of the electronic element 210 can be reduced.

[0060] Furthermore, the second surface 12 may have a region R2 exposed from the second resin layer 30. In a plan view, the region R1 exposed from the first resin layer 20 on the first surface 11 and the region R2 exposed from the second resin layer 30 on the second surface 12 may overlap.

[0061] This allows for efficient heat dissipation from the exposed regions R1 and R2, thereby dissipating heat from the electronic element 210, the heat generated in the composite wiring board 100 by the operation of the electronic element 210, and heat received from external sources other than the electronic element 210.

[0062] Furthermore, by efficiently transferring the heat generated in the electronic element 210, or the heat transferred to the electronic element 210 from the outside, to the region R2 where the second surface 12 is exposed, without passing through the second resin layer 30, the amount of heat moving from the composite wiring board 100 to the side portion 13 is increased, and as a result, the temperature of the electronic element 210 can be reduced.

[0063] Furthermore, the second surface 12 may also have an electronic element mounting region M1 on which the electronic element 210 is mounted in the region R2 exposed from the second resin layer 30.

[0064] Furthermore, compared to the case where the region R1 with the first surface 11 exposed and the region R2 with the second surface 12 exposed do not overlap in a plan view, the amount of deformation due to temperature changes on the front and back sides of the core layer 10 caused by the heat of the mounted electronic elements 210 can be made closer. Therefore, warping of the composite wiring board 100 due to the heat of the electronic elements 210 can be reduced.

[0065] Furthermore, if the second surface 12 has an exposed region R2 from the second resin layer 30, the first surface 11 may be completely covered by the first resin layer 20. This allows for efficient heat dissipation from the exposed region R2, dissipating heat from the electronic element 210, heat generated in the composite wiring board 100 by the operation of the electronic element 210, and heat received from external sources other than the electronic element 210.

[0066] <First conductor, second conductor, and third conductor> As shown in Figure 3, the first conductor 40 is located inside the core layer 10 and may extend from one of the first surface 11 and the second surface 12 to the other. Note that "extending" here does not necessarily mean extending along the shortest distance. For example, the first conductor 40 may have a wiring layer 42 in the middle, which is a portion that extends along the first surface 11.

[0067] The first conductor 40 may have a plurality of vias 41 and one or more wiring layers 42. The vias 41 penetrate one or more ceramic layers 14. The wiring layers 42 are located between adjacent ceramic layers 14 and may electrically connect the plurality of vias 41.

[0068] Thus, because the composite wiring board 100 has a first conductor 40 in the core layer 10, it offers greater design flexibility for the wiring compared to conventional composite wiring boards that have wiring only in an organic resin substrate.

[0069] In the example shown in Figure 3, the first conductor 40 is shown as having a wiring layer 42, but the first conductor 40 does not necessarily need to have a wiring layer 42. Also, the first conductor 40 may have a wiring layer located on the first surface 11 or the second surface 12 of the core layer 10.

[0070] As shown in Figures 7 and 8, a portion of the first conductor 40 may be exposed from the side portion 13. For example, the wiring layer 42 may be exposed from the main side portion 15.

[0071] This allows for efficient heat dissipation from the exposed first conductor 40, thereby efficiently dissipating heat from the electronic element 210. Furthermore, it facilitates checking the continuity of the wiring inside the composite wiring board 100. Additionally, the exposed first conductor 40, or a conductor connected to the exposed first conductor 40, can be used as an electrode to connect the electrodes of elements and components.

[0072] As shown in Figure 8, the wiring layer 42 may be exposed from the main side surface 15. The relative magnitudes of the distance L3 from the first surface 11 to the wiring layer 42 and the distance L4 from the second surface 12 to the wiring layer 42 in the thickness direction of the core layer 10 may coincide with the relative magnitudes of the length L1 of the side portion 13 covered by the first resin layer 20 and the length L2 of the side portion 13 covered by the second resin layer 30 in a cross-sectional view. For example, in Figure 8, L3 > L4 and L1 > L2, so the above two relative magnitudes coincide.

[0073] This ensures sufficient length from the exposed first conductor 40 to the first resin layer 20 located on the side surface 13. This prevents the first conductor 40 from being completely covered by the first resin layer 20. Furthermore, heat generated from the first conductor 40 is more easily dissipated from the side surface 13 than from the first resin layer 20, reducing the likelihood of the first resin layer 20 deforming or deteriorating due to this heat.

[0074] As shown in Figures 2 and 3, the first conductor 40 may be completely covered by the side portion 13. In other words, the first conductor 40 does not have to be exposed to the side portion 13.

[0075] This reduces the possibility of a short circuit occurring when the composite wiring board 100 comes into contact with conductive parts of other components or jigs and fixtures, or conductive debris generated from them, compared to the case where the first conductor 40 is exposed from the side portion 13.

[0076] As shown in Figure 3, the second conductor 50 is located inside the first resin layer 20 and may extend from one of the third surface 21 and the fourth surface 22 to the other. Note that "extending" here does not necessarily mean extending along the shortest distance. The second conductor 50 may be electrically connected to the first conductor 40 at the interface which is the joint surface between the core layer 10 and the first resin layer 20.

[0077] The second conductor 50 may have a plurality of vias 51. The vias 51 penetrate one or more organic resin layers 24. The second conductor 50 may have wiring layers located between adjacent organic resin layers 24 and electrically connecting the plurality of vias 51. The second conductor 50 may also have wiring layers or electrodes located on the fourth surface 22 of the first resin layer 20.

[0078] The third conductor 60 is located inside the second resin layer 30 and may extend from one of the fifth surface 31 and the sixth surface 32 to the other. Note that "extending" here does not necessarily mean extending along the shortest distance. The third conductor 60 may be electrically connected to the first conductor 40 at the interface which is the joint surface between the core layer 10 and the second resin layer 30.

[0079] The third conductor 60 may have a plurality of vias 61. The vias 61 penetrate one or more organic resin layers 34. The third conductor 60 may have wiring layers located between adjacent organic resin layers 34 that electrically connect the plurality of vias 61. The third conductor 60 may also have wiring layers or electrodes located on the sixth surface 32 of the second resin layer 30.

[0080] The first conductor 40 may be, for example, a metal conductor mainly composed of tungsten or molybdenum. For example, via 41 may be a metal conductor mainly composed of tungsten, and the wiring layer 42 may be a metal conductor mainly composed of molybdenum. Alternatively, via 41 may be a metal conductor mainly composed of molybdenum, and the wiring layer 42 may be a metal conductor mainly composed of tungsten. Furthermore, both via 41 and the wiring layer 42 may be metal conductors mainly composed of tungsten, or both via 41 and the wiring layer 42 may be metal conductors mainly composed of molybdenum. The first conductor 40 may be, for example, a metal conductor mainly composed of copper or gold, containing tungsten or molybdenum.

[0081] The second conductor 50 and the third conductor 60 may both be metal conductors mainly composed of copper. Alternatively, the second conductor 50 and the third conductor 60 may be metal conductors containing copper and bismuth. The electrical resistivity of the second conductor 50 and the third conductor 60 may be lower than that of the first conductor 40. In this case, the first conductor 40 may be a metal conductor mainly composed of tungsten or molybdenum, and the second conductor 50 and the third conductor 60 may be metal conductors mainly composed of copper.

[0082] The first conductor 40 may contain a glass material. In this case, the first conductor 40 is joined to the core layer 10, which also contains a glass material, via the glass material. Specifically, the glass material contained in the first conductor 40 can be integrated with the glass material contained in the core layer 10 by firing. This strengthens the bond between the core layer 10 and the first conductor 40 through an anchoring effect between the glass materials. Furthermore, this increases the rigidity of the core layer 10.

[0083] Furthermore, if the first conductor 40 contains glass material, the firing temperature of the core layer 10 and the first conductor 40 can be brought closer together during the firing process when manufacturing the composite wiring board 100. In addition, the shrinkage rate between the core layer 10 and the first conductor 40 can be adjusted.

[0084] The first conductor 40 and the second conductor 50 are located on the first surface 11 at least at the interface between the core layer 10 and the first resin layer 20. For example, if the first conductor 40 and the second conductor 50 were located on the first inclined surface 16, the curvature of the outer edge of the first resin layer 20 could cause the electrical connection between the first conductor 40 and the second conductor 50 to be interrupted. However, by having the first conductor 40 and the second conductor 50 located on the first surface 11, the possibility of the electrical connection between the first conductor 40 and the second conductor 50 being interrupted can be reduced.

[0085] Furthermore, the first conductor 40 and the third conductor 60 are located on the second surface 12 at least at the interface between the core layer 10 and the second resin layer 30. For example, if the first conductor 40 and the third conductor 60 were located on the second inclined surface 17, the curvature of the outer edge of the second resin layer 30 could cause the electrical connection between the first conductor 40 and the third conductor 60 to be interrupted. However, by having the first conductor 40 and the third conductor 60 located on the second surface 12, the possibility of the electrical connection between the first conductor 40 and the third conductor 60 being interrupted can be reduced.

[0086] Multiple first conductors 40 may be located inside the core layer 10. Multiple second conductors 50 may be located inside the first resin layer 20. Multiple third conductors 60 may be located inside the second resin layer 30. The distance between conductors such as vias located on the side on which the electronic element 210 is mounted may be smaller than the distance between first conductors 40 such as vias located inside the core layer 10. For example, when an electronic element 210 is mounted on the first resin layer 20, the distance between second conductors 50 such as vias located inside the first resin layer 20 may be smaller than the distance between first conductors 40 such as vias located inside the core layer 10. The wiring density of the second resin layer 30 may be lower or higher than the wiring density of the core layer 10.

[0087] <First Connecting Conductor> The first connecting conductor 70 may be a conductor containing a glass component. As shown in Figure 3, the first connecting conductor 70 is located between the core layer 10 and the first resin layer 20 and electrically connects the first conductor 40 and the second conductor 50. A composite wiring board 100 having such a first connecting conductor 70 offers a wider range of horizontal placement possibilities for the first conductor 40 and the second conductor 50 when connecting them, resulting in greater design flexibility.

[0088] The first connecting conductor 70 may be wider than the via 51 of the second conductor 50 that is in direct contact with the first connecting conductor 70 in the direction along the first surface 11. This makes it easier to align the first connecting conductor 70 with the via 51 of the second conductor 50, thereby improving the yield of the composite wiring board 100.

[0089] The first connecting conductor 70 may be bonded to the first surface 11 of the core layer 10 by a glass component. This glass component is included in both the first connecting conductor 70 and the core layer 10. As a result, the first connecting conductor 70 is firmly bonded to the core layer 10, which also contains a glass component, via the glass component.

[0090] Furthermore, for example, if only the first conductor 40 of the two conductors 40 and 50 contains a glass component, the first conductor 40 is firmly joined to the first connecting conductor 70, which also contains a glass component, via the glass component. As a result, the physical connection between the first conductor 40 and the first connecting conductor 70 is stable.

[0091] <Second connecting conductor> The second connecting conductor 80 may be a conductor containing a glass component. The second connecting conductor 80 is located between the core layer 10 and the second resin layer 30 and electrically connects the first conductor 40 and the third conductor 60. A composite wiring board 100 having such a second connecting conductor 80 offers a high degree of design flexibility.

[0092] The second connecting conductor 80 may be wider than the via 61 of the third conductor 60 that is in direct contact with the second connecting conductor 80 in the direction along the second surface 12. This makes it easier to align the second connecting conductor 80 with the via 61 of the third conductor 60, thereby improving the yield of the composite wiring board 100.

[0093] The second connecting conductor 80 may be bonded to the second surface 12 of the core layer 10 by a glass component. This glass component is included in both the second connecting conductor 80 and the core layer 10. As a result, the second connecting conductor 80 is firmly bonded to the core layer 10, which also contains a glass component, via the glass component.

[0094] Furthermore, for example, if only the first conductor 40 of the first conductor 40 and the third conductor 60 contains a glass component, the first conductor 40 is firmly joined to the second connecting conductor 80, which also contains a glass component, via the glass component. As a result, the physical connection between the first conductor 40 and the second connecting conductor 80 is stable.

[0095] <First Electrode and Second Electrode> As shown in Figure 9, the first electrode 91 may be located on the first resin layer 20. For example, the first electrode 91 may be located on the fourth surface 22. The first electrode 91 may be electrically connected to the second conductor 50. For example, the first electrode 91 may be electrically connected to the via 51. The first electrode 91 may also be electrically connected to the electronic element 210. In this way, the first electrode 91 may electrically connect the electronic element 210 and the second conductor 50.

[0096] The second electrode 92 may be located on the second resin layer 30. For example, the second electrode 92 may be located on the sixth surface 32. The second electrode 92 may be electrically connected to the third conductor 60. For example, the second electrode 92 may be electrically connected to the via 61. The second electrode 92 may also be electrically connected to the printed circuit board. In this way, the second electrode 92 may electrically connect the printed circuit board and the second conductor 50.

[0097] The pitch P1 between the first electrodes 91 may be smaller than the pitch P2 between the second electrodes 92. In this disclosure, pitch refers to the minimum distance between a plurality of electrodes.

[0098] This allows the composite wiring board 100 to function as an interposer. Furthermore, by independently controlling the arrangement density of electrodes 91 and 92 in the first resin layer 20 and the second resin layer 30, the amount of heat generated due to the arrangement density of electrodes 91 and 92 can be controlled in each of the first resin layer 20 and the second resin layer 30. As a result, the temperature distribution in the composite wiring board 100 can be set to the optimal conditions for reducing warping.

[0099] The first electrode 91 and the second electrode 92 may be composed of two or more metal layers. Of the two or more layers constituting the first electrode 91, the layer on the side of the first resin layer 20 may have the same main component as the second conductor 50. Also, of the two or more layers constituting the second electrode 92, the layer on the side of the second resin layer 30 may have the same main component as the third conductor 60. In this case, the main component may be copper.

[0100] Furthermore, among the two or more layers constituting the first electrode 91, the exposed layer may have a different main component from the second conductor 50. Similarly, among the two or more layers constituting the second electrode 92, the exposed layer may have a different main component from the third conductor 60. In this case, the main component of the exposed layer may be gold.

[0101] Furthermore, the core layer 10 may have through holes in the region R1 exposed from the first resin layer 20 and the region R2 exposed from the second resin layer 30. In other words, the composite wiring board 100 may have through holes that penetrate in the thickness direction.

[0102] <Electronic Module> Figure 10 is a cross-sectional view showing an example of the configuration of an electronic module 200 according to the embodiment. Note that the inclined surfaces 16 and 17 are omitted in Figure 10.

[0103] As shown in Figure 10, the electronic module 200 comprises a composite wiring board 100 and an electronic element 210. The electronic element 210 is mounted on the composite wiring board 100. The electronic element 210 may be mounted on the fourth surface 22 of the first resin layer 20 on the composite wiring board 100. For example, the first electrode 91 may be located on the fourth surface 22 of the first resin layer 20, and the first electrode 91 and the electronic element 210 may be connected by wire bonding.

[0104] By positioning the resin layers 20 and 30 on the inclined surfaces 16 and 17 of the side portion 13, the bonding area between the core layer 10 and the resin layers 20 and 30 increases compared to the case where all of the side portion 13 is a vertical surface. Therefore, the bonding strength between the core layer 10 and the resin layers 20 and 30 can be improved. As a result, even if the composite wiring board 100 warps due to the heat of the electronic element 210, the possibility of the composite wiring board 100 peeling off and being damaged at the interface between the core layer 10 and the resin layers 20 and 30 can be reduced.

[0105] Although the present disclosure has been described in detail above, this disclosure is not limited to the embodiments described above, and various modifications and improvements are possible without departing from the gist of this disclosure.

[0106] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. Indeed, the above embodiments can be embodied in a variety of forms. Furthermore, the above embodiments may be omitted, replaced, or modified in various ways without departing from the scope and spirit of the appended claims.

[0107] Furthermore, this technology can also take the following configurations: (1) A composite wiring board comprising: a core layer containing a ceramic material having a first surface, a second surface located opposite to the first surface, and a side portion connecting the first surface and the second surface; a first resin layer containing a first resin material that is in contact with the first surface; and a second resin layer containing a second resin material that is in contact with the second surface, wherein the first resin layer and the second resin layer each cover a part of the side portion, and the side portion has portions exposed from the first resin layer and the second resin layer. (2) The composite wiring board according to (1), wherein the side portion has a main side surface located in the center in the thickness direction of the core layer, a first inclined surface connecting the main side surface and the first surface, and a second inclined surface connecting the main side surface and the second surface, wherein the first resin layer covers at least a part of the first inclined surface, and the second resin layer covers at least a part of the second inclined surface. (3) The composite wiring board according to (1) or (2), wherein the first resin material and the second resin material are the same material. (4) The composite wiring board according to any one of (1) to (3), wherein the thermal conductivity of the ceramic material is higher than the thermal conductivity of the first resin material and the thermal conductivity of the second resin material. (5) The composite wiring board according to any one of (1) to (4), wherein, in a cross-sectional view, the length of the side portion covered by the first resin layer and the length of the side portion covered by the second resin layer are different. (6) The composite wiring board according to any one of (1) to (5), comprising a conductor located inside the core layer, wherein a part of the conductor is exposed from the side portion. (7) The composite wiring board according to any one of (1) to (5), comprising a conductor located inside the core layer, wherein the side portion completely covers the conductor. (8) The composite wiring board according to any one of (1) to (7), wherein the thickness of the first resin layer and the thickness of the second resin layer are different. (9) The composite wiring board according to (8), wherein the first resin layer has an electronic element mounting region on which an electronic element is mounted, and the thickness of the first resin layer is greater than the thickness of the second resin layer.(10) The composite wiring board according to any one of (1) to (9), wherein the first surface has a region exposed from the first resin layer. (11) The composite wiring board according to (10), wherein the first surface has an electronic element mounting region on the region exposed from the first resin layer where an electronic element is mounted. (12) The composite wiring board according to (10) or (11), wherein the second surface has a region exposed from the second resin layer, and in a plan view, the region of the first surface exposed from the first resin layer and the region of the second surface exposed from the second resin layer overlap. (13) The composite wiring board according to any one of (1) to (12), wherein the first resin layer has a third surface bonded to the first surface and a fourth surface located opposite to the third surface, the second resin layer has a fifth surface bonded to the second surface and a sixth surface located opposite to the fifth surface, and has a plurality of first electrodes located on the fourth surface of the first resin layer and a plurality of second electrodes located on the sixth surface of the second resin layer, and the pitch between the first electrodes is smaller than the pitch between the second electrodes. (14) The composite wiring board according to any one of (1) to (5), wherein the core layer comprises a conductor located inside the core layer, a part of the conductor is exposed from the side surface, and the relationship between the distance from the first surface to the conductor and the distance from the second surface to the conductor in the thickness direction of the core layer is the same as the relationship between the length of the side surface covered by the first resin layer and the length of the side surface covered by the second resin layer in a cross-sectional view. (15) An electronic module comprising a composite wiring board as described in any one of (1) to (14) above, and an electronic element mounted on the first resin layer.

[0108] 10 Core layer 11 First surface 12 Second surface 13 Side surface 14 Ceramic layer 15 Main side surface 16 First inclined surface 17 Second inclined surface 20 First resin layer 21 Third surface 22 Fourth surface 23 First side surface 24 Organic resin layer 30 Second resin layer 31 Fifth surface 32 Sixth surface 33 Second side surface 34 Organic resin layer 40 First conductor 41 Via 42 Wiring layer 50 Second conductor 51 Via 60 Third conductor 61 Via 70 First connecting conductor 80 Second connecting conductor 91 First electrode 92 Second electrode 100 Composite wiring board 200 Electronic module 210 Electronic element L1 Length L2 Length L3 Distance L4 Distance P1 Pitch P2 Pitch R1 Area R2 Area T1 Thickness T2 Thickness

Claims

1. A composite wiring board comprising: a core layer containing a ceramic material having a first surface, a second surface located opposite the first surface, and side portions connecting the first surface and the second surface; a first resin layer containing a first resin material that is in contact with the first surface; and a second resin layer containing a second resin material that is in contact with the second surface, wherein the first resin layer and the second resin layer each cover a portion of the side portions, and the side portions have portions exposed from the first resin layer and the second resin layer.

2. The composite wiring board according to claim 1, wherein the side surface has a main side surface located in the center in the thickness direction of the core layer, a first inclined surface connected to the main side surface and the first surface, and a second inclined surface connected to the main side surface and the second surface, the first resin layer covers at least a portion of the first inclined surface, and the second resin layer covers at least a portion of the second inclined surface.

3. The composite wiring board according to claim 1 or 2, wherein the first resin material and the second resin material are the same material.

4. The composite wiring board according to any one of claims 1 to 3, wherein the thermal conductivity of the ceramic material is higher than that of the first resin material and the second resin material.

5. A composite wiring board according to any one of claims 1 to 4, wherein, in a cross-sectional view, the length of the side portion covered by the first resin layer and the length of the side portion covered by the second resin layer are different.

6. A composite wiring board according to any one of claims 1 to 5, comprising a conductor located inside the core layer, wherein a portion of the conductor is exposed from the side portion.

7. A composite wiring board according to any one of claims 1 to 5, comprising a conductor located inside the core layer, wherein the side portion completely covers the conductor.

8. The composite wiring board according to any one of claims 1 to 7, wherein the thickness of the first resin layer and the thickness of the second resin layer are different.

9. The composite wiring board according to claim 8, wherein the first resin layer has an electronic element mounting region on which an electronic element is mounted, and the thickness of the first resin layer is greater than the thickness of the second resin layer.

10. The composite wiring board according to any one of claims 1 to 9, wherein the first surface has a region exposed from the first resin layer.

11. The composite wiring board according to claim 10, wherein the first surface has an electronic element mounting region in the region exposed from the first resin layer, on which an electronic element is mounted.

12. The composite wiring board according to claim 10 or 11, wherein the second surface has a region exposed from the second resin layer, and in a plan view, the region of the first surface exposed from the first resin layer and the region of the second surface exposed from the second resin layer overlap.

13. The composite wiring board according to any one of claims 1 to 12, wherein the first resin layer has a third surface bonded to the first surface and a fourth surface located opposite to the third surface, the second resin layer has a fifth surface bonded to the second surface and a sixth surface located opposite to the fifth surface, and the composite wiring board has a plurality of first electrodes located on the fourth surface of the first resin layer and a plurality of second electrodes located on the sixth surface of the second resin layer, and the pitch between the first electrodes is smaller than the pitch between the second electrodes.

14. A composite wiring board according to any one of claims 1 to 5, comprising a conductor located inside the core layer, wherein a portion of the conductor is exposed from the side portion, and the relative magnitudes of the distance from the first surface to the conductor and the distance from the second surface to the conductor in the thickness direction of the core layer coincide with the relative magnitudes of the length of the side portion covered by the first resin layer and the length of the side portion covered by the second resin layer in a cross-sectional view.

15. An electronic module comprising a composite wiring board according to any one of claims 1 to 14, and an electronic element mounted on the first resin layer.

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