Wiring board, electrical device, and electrical device structure

Abstract

This wiring board has a base and a conductor. The base is a layered body of a ceramic base wiring layer and an organic resin base wiring layer. The organic resin base wiring layer has an organic resin base as an insulating base. The ceramic base wiring layer has a ceramic base as an insulating base. The organic resin base has a higher coefficient of thermal expansion than the ceramic base. If the ceramic-base-side surface of the layered body is designated as a first surface and the organic-resin-base-side surface of the layered body is designated as a second surface, the first surface and the second surface of the layered body face in opposite directions. The conductor has a first terminal group and a second terminal group. The first terminal group is provided on the first surface of the layered body. The second terminal group is provided on the second surface of the layered body. The first surface is a surface for mounting electrical elements. The second surface is a surface for connecting to an external circuit board.

Description

Wiring board, electric device and electric device structure

[0001] Disclosed embodiments relate to wiring boards, electrical devices, and electrical device structures.

[0002] A wiring board has been proposed in which multiple circuit sections made of organic resin are laminated on a ceramic substrate, and the circuit sections are provided with multiple connection conductors that penetrate between the laminated layers.

[0003] Japanese Patent Application Laid-Open No. 2019-207977

[0004] A wiring board according to one aspect of the embodiment includes a base and a conductor. The base is a laminate of a ceramic base wiring layer and an organic resin base wiring layer. The organic resin base wiring layer includes an organic resin base as an insulating base. The ceramic base wiring layer includes a ceramic base as an insulating base. The organic resin base has a higher thermal expansion coefficient than the ceramic base. When the surface of the laminate facing the ceramic base is defined as a first surface and the surface facing the organic resin base is defined as a second surface, the first surface and the second surface of the laminate are surfaces facing opposite each other. The conductor includes a first terminal group and a second terminal group. The first terminal group is provided on the first surface of the laminate. The second terminal group is provided on the second surface of the laminate. The first surface is a surface on which electrical elements are mounted. The second surface is a surface for connection to an external circuit board.

[0005] FIG. 1 is an explanatory diagram showing an example of an electric device structure according to an embodiment. FIG. 2 is a diagram showing an example of the characteristics of each member constituting the electric device structure. FIG. 3 is a cross-sectional view showing an example of a wiring board according to a first embodiment. FIG. 4 is a cross-sectional view showing an example of a wiring board according to a second embodiment. FIG. 5 is a cross-sectional view showing an example of a wiring board according to a third embodiment. FIG. 6 is an enlarged plan view of a portion of the wiring board shown in FIG. 5. FIG. 7 is a cross-sectional view showing an example of a wiring board according to a fourth embodiment. FIG. 8 is a cross-sectional view showing an example of a wiring board according to a fifth embodiment. FIG. 9 is a cross-sectional view showing another example of a wiring board according to an embodiment. FIG. 10 is a cross-sectional view showing another example of a wiring board according to an embodiment. FIG. 11 is an explanatory diagram showing an example of a method for manufacturing a wiring board according to Sample 1. FIG. 12 is a plan view showing a wiring board according to an experimental example. FIG. 13 is a diagram showing evaluation results of the wiring board according to the experimental example.

[0006] In the above-mentioned wiring board, for example, the ceramic layer is disposed on the external circuit board side, and therefore there is room for improvement in that the reliability of the connection between the ceramic layer and the external circuit board is likely to decrease due to the difference in the thermal expansion coefficients between the ceramic layer and the external circuit board.

[0007] Therefore, there is a need to provide a wiring board, an electric device, and an electric device structure that can improve connection reliability.

[0008] Hereinafter, embodiments for carrying out a wiring board, an electric device, and an electric device structure according to the present disclosure (hereinafter referred to as "embodiments") will be described in detail with reference to the drawings. Note that the wiring board according to the present disclosure is not limited to these embodiments. Furthermore, each embodiment can be appropriately combined within a range that does not cause contradictions in the processing content.

[0009] 1 is an explanatory diagram showing an example of an electric device structure according to an embodiment. The electric device structure 5 has an electric device 3 and an external circuit board 4. The electric device 3 has a wiring board 1 and an electric element 2. The electric element 2 is mounted on the first surface 101 of the wiring board 1, and the external circuit board 4 is connected to the second surface 201 of the wiring board 1.

[0010] The wiring board 1 has a ceramic substrate wiring layer (see FIG. 3) located on the first surface 101 side and an organic resin substrate wiring layer (see FIG. 3) located on the second surface 201 side. The electrical device structure 5 has a structure in which an electrical element 2, a ceramic substrate wiring layer, an organic resin substrate wiring layer, and an external circuit board 4 are laminated in this order. The ceramic substrate wiring layer has a ceramic substrate as an insulating substrate. The organic resin substrate wiring layer has an organic resin substrate as an insulating substrate.

[0011] The order of the coefficients of thermal expansion of the members constituting the electrical device structure 5 is, for example, electrical elements < ceramic substrate wiring layer < organic resin substrate wiring layer. The external circuit board 4 has a coefficient of thermal expansion equivalent to that of the organic resin substrate wiring layer.

[0012] 2 is a diagram showing an example of the characteristics of each member constituting the electrical device structure, where the order of thermal expansion coefficient is electrical element < ceramic substrate < organic resin substrate.

[0013] For example, the Young's modulus of a ceramic substrate is higher than that of an organic resin substrate. Since the ceramic substrate has a higher Young's modulus and a smaller coefficient of thermal expansion than the organic resin substrate, mounting the electrical element 2 on the ceramic substrate wiring layer side of the wiring board 1 provides higher durability against thermal stress.

[0014] When the electric element 2 is driven, it generates heat. If the electric element 2 is mounted on a ceramic substrate wiring layer with high thermal conductivity, the heat dissipation from the ceramic substrate wiring layer to the outside is improved.

[0015] Since the external circuit board 4 is generally larger in size than the wiring board 1, for example, even if the external circuit board 4 and the organic resin base wiring layer of the wiring board 1 have the same thermal expansion coefficient, the amount of deformation (elongation) of the external circuit board 4 will be greater. However, if an organic resin base wiring layer is disposed between the ceramic base wiring layer and the external circuit board 4, it is possible to reduce the transfer of heat from the electric element 2 to the external circuit board 4. Therefore, since the amount of deformation of the external circuit board 4 can be reduced, it is possible to improve the connection reliability of the connection points between the members of the electric device structure 5.

[0016] If the ceramic substrate wiring layer were removed from the configuration of the wiring board 1 of the present disclosure, in which the ceramic substrate wiring layer is disposed on the electrical element 2 side and the organic resin substrate wiring layer is disposed on the external circuit board 4 side, the electrical element 2 would be mounted directly on the surface of the organic resin substrate wiring layer. In such a configuration, the difference in thermal expansion coefficient between the electrical element 2 and the organic resin substrate wiring layer is large, increasing the likelihood of malfunctions occurring in the electrical element 2 due to thermal expansion of the organic resin substrate wiring layer. This malfunction is particularly likely to be significant in electrical device structures 5 having large electrical elements 2 (20 mm square or larger).

[0017] On the other hand, if the organic resin substrate wiring layer is removed from the configuration of the wiring board 1 of the present disclosure, the ceramic substrate wiring layer will be directly connected to the external circuit board 4. In such a case, the difference in thermal expansion coefficient between the ceramic substrate wiring layer and the external circuit board 4 is large, which makes it easier for the reliability of the mounting on the external circuit board 4 (called secondary mounting; the electrical element 2 side is considered primary mounting) to be impaired. Here, the external circuit board 4 may be, for example, a composite of organic resin and glass cloth.

[0018] First Embodiment FIG. 3 is a cross-sectional view showing an example of a wiring board according to a first embodiment. The wiring board 1 has a base and a conductor. The base is a laminate of a ceramic base wiring layer 10 and an organic resin base wiring layer 20. The organic resin base wiring layer 20 has an organic resin base 21 as an insulating base. The ceramic base wiring layer 10 has a ceramic base 11 as an insulating base. The organic resin base 21 has a higher thermal expansion coefficient than the ceramic base 11. When the surface of the base laminate facing the ceramic base 11 is defined as a first surface 101 and the surface facing the organic resin base 21 is defined as a second surface 201, the first surface 101 and the second surface 201 are surfaces facing opposite each other in the laminate. The conductor has a first terminal group and a second terminal group. The first terminal group (not shown) is provided on the first surface 101 of the laminate. A second terminal group (not shown) is provided on a second surface 201 of the laminate. The first surface 101 is a mounting surface for the electric element 2 (see FIG. 1 ). The second surface 201 is a connection surface for connecting to an external circuit board 4 (see FIG. 1 ).

[0019] 3, the wiring board 1 according to this embodiment has a ceramic base wiring layer 10 and an organic resin base wiring layer 20. The wiring board 1 has a first surface 101 located on the ceramic base wiring layer 10 side and a second surface 201 located on the organic resin base wiring layer 20 side.

[0020] The ceramic substrate wiring layer 10 includes a ceramic substrate 11 and a surface conductor layer 12. The ceramic substrate 11 is, for example, an insulating substrate made of ceramic. The ceramic substrate 11 may be, for example, an alumina-based or glass-ceramic-based ceramic, or may be a dielectric material such as cordierite, zirconia, barium titanate, strontium titanate, or calcium titanate, or may be aluminum titanate or lead zirconate titanate (PZT). The ceramic substrate 11 may also include, for example, a plurality of ceramics.

[0021] The surface conductor layer 12 is located on the surface of the ceramic substrate 11. The surface conductor layer 12 protrudes from the third surface 102. The third surface 102 is the surface of the ceramic substrate wiring layer 10 that contacts the organic resin substrate wiring layer 20. The surface conductor layer 12 may be, for example, a line-shaped wiring, a circular, rectangular, or other angular pad, or a solid power supply layer or ground layer. The surface conductor layer 12 may be, for example, smaller in area than the main surface of the ceramic substrate wiring layer 10.

[0022] 3 illustrates an example in which the surface conductor layer 12 protrudes from the third surface 102 of the ceramic substrate wiring layer 10 by a thickness equivalent to the thickness of the surface conductor layer 12. In contrast, the surface conductor layer 12 may protrude from the third surface 102 of the ceramic substrate wiring layer 10 by a smaller proportion than the thickness of the surface conductor layer 12.

[0023] The surface conductor layer 12 may be made of a conductor such as tungsten (W), molybdenum (Mo), a W-Mo mixture, a W-Mo alloy, a W-Mo intermetallic compound, copper (Cu), silver (Ag), or nickel (Ni). The surface conductor layer 12 may also contain ceramic powder.

[0024] The organic resin base wiring layer 20 is located below the ceramic base wiring layer 10. The organic resin base wiring layer 20 has an organic resin base 21 and a plurality of interlayer connection conductors 22.

[0025] The organic resin base 21 has, for example, an organic material as an insulating base. The organic resin base 21 may be, for example, an epoxy resin, an acrylic resin, a polycarbonate resin, a polyimide resin, an olefin resin, or a polyphenylene resin. The organic resin base 21 may also be, for example, polytetrafluoroethylene (PTFE) or other fluororesins or polyphenylene ether resins.

[0026] The interlayer connection conductor 22 extends in the thickness direction of the organic resin base wiring layer 20, and is positioned so that one end 221 is exposed on the second surface 201, which is the surface of the organic resin base wiring layer 20. The other end 222 of the interlayer connection conductor 22 is electrically connected to the surface conductor layer 12.

[0027] The interlayer connection conductor 22 may contain, for example, copper powder, tin (Sn) powder, or bismuth (Bi) powder. In the interlayer connection conductor 22, the volume ratio of the metal components, such as copper, tin, and bismuth, is preferably 60% or more and 90% or less. When the volume ratio of the metal components is within this range, the conductivity of the interlayer connection conductor 22 can be increased. Furthermore, the adhesion between the organic resin base 21 and the surface conductor layer 12 and the interlayer connection conductor 22 can be improved. The volume ratio of the metal components may be determined as an area ratio by, for example, examining a cross section of the interlayer connection conductor 22 using an electron microscope equipped with an analyzer. In this case, the determined area ratio may be considered as a volume ratio. In the interlayer connection conductor 22, the total amount of copper, tin, and bismuth is preferably equal. Furthermore, the total amount of tin and bismuth is preferably equal. Furthermore, the remainder of the interlayer connection conductor 22 may be the same material as the organic resin base 21, such as epoxy resin.

[0028] The organic resin base 21 also has a first region 211 and a second region 212. The first region 211 is a portion of the organic resin base 21 that is located on the surface conductor layer 12. The second region 212 is a portion of the organic resin base 21 other than the first region 211 that is located on the organic resin base 21.

[0029] In the wiring board 1, the density of the first region 211 of the organic resin base 21 located on the surface conductor layer 12 may be higher than the density of the second region 212 located outside the surface conductor layer 12. For example, if the surface conductor layer 12 is provided on the third surface 102 of the ceramic base 11 and the interlayer connection conductor 22 is provided in the organic resin base wiring layer 20, moisture is less likely to penetrate from the second region 212 of the organic resin base 21 to the first region 211 around the interlayer connection conductor 22. This allows the wiring board 1 to reduce a decrease in insulation resistance.

[0030] Here, methods for evaluating density include determining the number or total area ratio of voids found in the first region 211 and the second region 212, and measuring the density of the cut-out portions of the first region 211 and the second region 212. Of these, the method of determining the total area ratio of voids present in a region per unit area is preferable, because differences tend to appear even in very small regions.

[0031] The ceramic substrate wiring layer 10 may have, for example, a conductor layer located inside the ceramic substrate 11. The ceramic substrate wiring layer 10 may have, for example, a plurality of ceramic substrates 11 stacked in the thickness direction.

[0032] Furthermore, the organic resin substrate wiring layer 20 may have, for example, a conductor layer located inside and / or on the surface of the organic resin substrate 21 .

[0033] Second Embodiment Fig. 4 is a cross-sectional view showing an example of a wiring board according to a second embodiment. As shown in Fig. 4, the wiring board 1 may have a coated conductor layer 30 located on the surface conductor layer 12.

[0034] In this way, when the coated conductor layer 30 is provided on the surface conductor layer 12, the thickness of the first region 211 of the organic resin base 21 becomes even smaller than that of the second region 212. The first region 211 may also be even denser than the second region 212. This makes it even more difficult for moisture to penetrate from the first region 211 to the interlayer connection conductor 22, for example, and can improve the electrical reliability of the interlayer connection conductor 22.

[0035] Third Embodiment Fig. 5 is a cross-sectional view showing an example of a wiring board according to a third embodiment. Fig. 6 is an enlarged plan view of a portion of the wiring board shown in Fig. 5. As shown in Figs. 5 and 6, in the wiring board 1, the interlayer connection conductor 22 constituting the organic resin base wiring layer 20 may have an inner region 22a and an outer periphery region 22b. Here, the inner region 22a is located inside the outer periphery region 22b when the organic resin base wiring layer 20 is viewed in plan. In other words, the inner region 22a is surrounded by the outer periphery region 22b. The outer periphery region 22b refers to a portion located near the outer periphery of the interlayer connection conductor 22. The outer periphery region refers to a portion occupying a predetermined volume inside the outline indicating the periphery of the interlayer connection conductor 22.

[0036] In the peripheral region 22b, the resin component is positioned so as to form a strip in the longitudinal direction of the interlayer connection conductor 22 (thickness direction of the organic resin base wiring layer 20). A region in which the resin component is positioned so as to form a strip in the longitudinal direction (thickness direction) of the interlayer connection conductor 22 is sometimes referred to as a mixed region. The mixed region is a region in which the resin component and the metal described below are mixed. Furthermore, the inner region 22a may contain less or almost no resin component compared to the peripheral region 22b. The term "strip-shaped" refers to a long shape. Here, the term "long shape" refers to a shape having an aspect ratio of, for example, 2 or more. Specifically, when a cross section obtained by cutting or polishing the wiring substrate 1 is observed with an electron microscope and photographed, the shape of the resin component in the interlayer connection conductor 22 seen in the photograph has the aspect ratio specified above.

[0037] In the outer peripheral region 22b, a resin component is contained in the gaps between the conductors that make up the interlayer connection conductors 22, and this resin component is located in a band shape. Therefore, the filling rate of the interlayer connection conductors 22 is higher in the outer peripheral region 22b than in the inner region 22a, making it even more difficult for moisture to penetrate into the interlayer connection conductors 22. This allows the wiring board 1 to further reduce a decrease in insulation resistance.

[0038] Here, the resin component present in the outer peripheral region 22 b of the interlayer connection conductor 22 may be, for example, a component of the organic resin contained in the organic resin base 21 .

[0039] For example, when a raw sheet of the organic resin base wiring layer 20 (filled with a conductive paste that is the material for the interlayer connection conductor 22) is laminated on top of the ceramic base wiring layer 10 and heated and pressurized, the resin component present in the outer peripheral region 22b may migrate from the organic resin base 21 of the organic resin base wiring layer 20, and a mixed region that exists in a band shape in the longitudinal direction of the interlayer connection conductor 22 may be formed in the outer peripheral region 22b.

[0040] The width of the mixed region, that is, the thickness of the outer peripheral region 22b along the radial direction of the interlayer connection conductor 22, is determined by the pressure, temperature and time of the pressurizing and heating during lamination and pressure bonding.

[0041] The thickness of the outer peripheral region 22 b along the radial direction of the interlayer connection conductor 22 may be, for example, not less than ⅙ and not more than ½ of the diameter of the interlayer connection conductor 22 .

[0042] As shown in FIG. 6, the outer peripheral region 22b is preferably formed so as to surround the periphery of the inner region 22a of the interlayer connection conductor.

[0043] It is preferable that no resin component is present in the inner region 22a located radially inside the interlayer connection conductor 22. This allows the wiring board 1 to ensure the conductivity of the interlayer connection conductor 22.

[0044] 7 is a cross-sectional view showing an example of a wiring board according to a fourth embodiment. In Fig. 7, the interlayer connection conductor 22 is also described by dividing it into an inner region 22a and an outer peripheral region 22b, as in Fig. 5.

[0045] As described above, the interlayer connection conductor 22 contains a metal component. In particular, the interlayer connection conductor 22 contains particulate metal. The outer peripheral region 22b of the interlayer connection conductor 22 may have a higher proportion of metal particles than the inner region 22a located inside the outer peripheral region 22b. In the outer peripheral region 22b, the region excluding the metal particle portion is preferably filled with a resin component.

[0046] In the outer peripheral region 22b, the metals are connected by a resin component with a weak bonding strength and a lower elastic modulus than the metals, and stress caused by the difference in thermal expansion coefficient between the interlayer connection conductors 22 and the organic resin base 21 located around them is easily alleviated. This makes it possible to prevent problems such as peeling between the interlayer connection conductors 22 and the organic resin base 21 around them. This allows the wiring board 1 to further reduce a decrease in insulation resistance.

[0047] Here, it is preferable that the particulate metal has an aspect ratio of 2 or less when viewed in cross section of the wiring board 1. When the interlayer connection conductor 22 constituting the wiring board 1 has particulate metal with such an aspect ratio, the binding force within the metal is smaller than that of an ingot-like metal in which the metal particles are integrated without gaps.

[0048] On the other hand, the metal located in the inner region 22a may have, for example, a shape in which the metal is interconnected. By forming a conductor in the inner region 22a in which the metal is interconnected, for example, the interface resistance between adjacent metal particles is reduced and the conductivity is increased. Note that the inner region 22a may have voids to the extent that the desired conductivity is obtained.

[0049] 8 is a cross-sectional view showing an example of a wiring board according to a fifth embodiment. As shown in Fig. 8, the diameter of the interlayer connection conductor 22 of the wiring board 1 may be smaller at a portion 24 near a second surface 201, which is the surface of the organic resin base 21, than at a portion 23 located at the center in the thickness direction of the organic resin base wiring layer 20.

[0050] Since the peripheral surface 25 of the interlayer connection conductor 22 facing the organic resin base 21 has a partially rounded shape, the surface area of ​​the interlayer connection conductor 22 is reduced, making it less susceptible to deformation due to external pressure. Even if the organic resin base 21 undergoes significant deformation, the amount of deformation of the interlayer connection conductor 22 is likely to remain small. This makes it possible to improve the connection reliability between the interlayer connection conductor 22 and the external circuit board 4 that is electrically mounted on it.

[0051] 8, the diameter of the interlayer connection conductor 22 in the wiring board 1 may be gradually reduced from near the center toward the ends in the thickness direction of the organic resin base 21. This makes it easier for the interlayer connection conductor 22 to undergo a mechanical effect that changes its shape from a polyhedron to a sphere, making the wiring board 1 less susceptible to deformation or breakage.

[0052] Furthermore, around the end of the interlayer connection conductor 22 located near the surface (second surface 201) of the organic resin base 21, the organic resin contained in the organic resin base 21 may, for example, penetrate deeply toward the center in the radial direction of the interlayer connection conductor 22 and surround it. This can further reduce deformation of the interlayer connection conductor 22. As a result, even when the external circuit board 4 is connected to the surface (second surface 201) of the organic resin base 21 at high temperature or pressure, the interlayer connection conductor 22 of the wiring board 1 is less likely to deform.

[0053] Other Embodiments FIGS. 9 and 10 are cross-sectional views showing other examples of wiring boards according to embodiments.

[0054] The wiring board 1 may have a first surface wiring layer 16 located on the first surface 101 and a second surface wiring layer 29 located on the second surface 201. Both the first surface wiring layer 16 and the second surface wiring layer 29 may be circular in plan view. In this case, the diameter of the second surface wiring layer 29 in plan view may be larger than the diameter of the first surface wiring layer 16 in plan view. The organic resin base 21 has a larger thermal expansion coefficient than the ceramic base 11, resulting in greater dimensional change during heating and cooling. For example, when connecting the organic resin base wiring layer 20 to an external circuit board 4, electrical connection can be easily ensured even if the position of the second surface wiring layer 29 of the organic resin base wiring layer 20 is misaligned from the corresponding connection pad on the external circuit board 4. This improves the alignment effect of a bonding material (a molten metal material such as solder) located between the organic resin base wiring layer 20 and the external circuit board 4.

[0055] The wiring board 1 may have a conductor layer 13 located inside the ceramic base 11. The wiring board 1 may also have a conductor layer 26 located inside the organic resin base 21.

[0056] Furthermore, the thickness of the organic resin base 21 may be, for example, in the range of 0.05 to 0.2 when the thickness of the ceramic base 11 is taken as 1. When the thickness of the organic resin base 21, which has a low elastic modulus, is thinner than the thickness of the ceramic base 11, the ceramic base 11 is less likely to deform even when subjected to loads such as thermal expansion of the wiring board 1 or loads.

[0057] Of the second surface wiring layer 29 provided on the organic resin base 21, the surface wiring layer 27, which is a copper foil portion, may be entirely embedded in the organic resin base 21. Furthermore, of the second surface wiring layer 29, the plating film 28 portion may entirely protrude from the surface (second surface 201) of the organic resin base 21.

[0058] Furthermore, the first surface wiring layer 16 provided on the ceramic base 11 may have a portion in the thickness direction embedded in the ceramic base 11 (surface wiring layer 14). Furthermore, a portion of the surface wiring layer 14 may protrude from the surface (first face 101) of the ceramic base 11. Furthermore, the first surface wiring layer 16 may have a plating film 15 of Ni, Au, or the like further formed on the surface of the surface wiring layer 14.

[0059] (Experimental Examples) Wiring substrates 1 according to the following samples 1 to 7 were fabricated and their characteristics were evaluated.

[0060] (Fabrication of Sample 1) Fig. 11 is an explanatory diagram showing an example of a manufacturing method for a wiring board according to Sample 1. First, a fired ceramic substrate wiring layer 10 and an uncured organic resin substrate wiring layer 20 were prepared. The ceramic substrate wiring layer 10 has a copper metallized film 120 on the surface of a glass ceramic insulating substrate (ceramic substrate 11). The metallized film 120 protrudes from the surface of the insulating substrate by a thickness close to that of the surface conductor layer 12.

[0061] The uncured organic resin base wiring layer 20 has an uncured interlayer connection conductor 220 penetrating the uncured organic resin base 21 in the thickness direction. The uncured organic resin base 21 was made using a thermosetting epoxy resin as the organic material (resin component). The uncured interlayer connection conductor 220 contains 50 mol % copper powder, 25 mol % Sn powder, 25 mol % Bi powder, and the remainder epoxy resin.

[0062] The wiring layer is formed by transferring patterned copper foil (initially attached to a PET film) onto the surface of the uncured organic resin base 21. The surface wiring layers formed on the first surface 101 (surface of the ceramic base wiring layer 10) and the second surface 201 (surface of the organic resin base wiring layer 20) of the wiring board 1 are both circular. 64 circular surface wiring layers were formed on each of the first surface 101 and the second surface 201. The diameter of the surface wiring layer formed on the first surface 101 was 200 μm, and the diameter of the surface wiring layer formed on the second surface 201 was 500 μm.

[0063] The area of ​​each of the surface wiring layers formed on the second surface 201 was 10 times the area of ​​each of the surface wiring layers formed on the first surface 101. The surface wiring layers on the first surface 101 were arranged in a lattice pattern in the center when the first surface 101 on the ceramic base 11 side was viewed in a plan view. The surface wiring layers on the second surface 201 were arranged so as to surround the peripheral portion when the second surface 201 on the organic resin base 21 side was viewed in a plan view. 64 surface wiring layers on the second surface 201 were connected in series.

[0064] It was confirmed by an electrical characteristic evaluation (resistance evaluation) that the ceramic substrate wiring layer 10 and the organic resin substrate wiring layer 20 were electrically connected by the interlayer connection conductor 22. The thermal expansion coefficient of the ceramic substrate 11 (glass ceramic) was 12×10 －６ / K, and the thermal expansion coefficient of the ceramic substrate wiring layer 10 having the wiring layer is 13×10 －６ / K, and the thermal expansion coefficient of the organic resin base 21 is 30×10 －６ / K, and the thermal expansion coefficient of the organic resin base wiring layer 20 having the wiring layer is 20×10 －６ / K.

[0065] Although not used in the experimental example, alumina ceramics may be used instead of glass ceramics as the ceramic substrate 11. In such a case, for example, W, W—Cu, Mo, etc. can be used as the conductor. The thermal expansion coefficient of such alumina ceramics is, for example, 6×10 －６ / K~8×10 －６ / K.

[0066] Next, the fired ceramic substrate wiring layer 10 and the uncured organic resin substrate wiring layer 20 were stacked together, and then pressurized and heated for 15 seconds at a temperature of 75°C and a pressure of 3 Pa in a vacuum atmosphere. The uncured organic resin substrate wiring layer 20 was placed on a base, and the fired ceramic substrate wiring layer 10 was placed on top of it, followed by a pressurized and heated treatment (250°C, 10 MPa, 15 seconds). This operation resulted in the copper foil being embedded in the uncured organic resin substrate 21. This operation yielded a wiring board 1 (sample 1: see FIG. 3 ) in which the ceramic substrate wiring layer 10 was located on the organic resin substrate wiring layer 20.

[0067] In the wiring board 1 of Sample 1, the first surface 101 (the surface on the ceramic base wiring layer 10 side) is a surface on which the electric element 2 is mounted, while the second surface 201 (the organic resin base wiring layer 20 side) is a surface to be connected to the external circuit board 4.

[0068] In addition, since the wiring board 1 of sample 1 has a surface conductor layer protruding from the ceramic base wiring layer 10, the first region 211 of the organic resin base 21 constituting the organic resin base wiring layer 20 overlapping the surface conductor layer 12 is further pressurized compared to the second region 212 other than the first region 211 (where the surface conductor layer 12 of the ceramic base wiring layer 10 exists), and is therefore more densified.

[0069] (Preparation of Sample 2) A nickel plating film was formed on the surface of the surface conductor layer 12 of the ceramic substrate wiring layer 10 used in Sample 1, and a sintering treatment was performed at a temperature of 700°C in a nitrogen atmosphere to obtain a wiring substrate 1 (Sample 2: see Figure 4) having a coated conductor layer 30 on the surface conductor layer 12.

[0070] (Preparation of Sample 3) A wiring substrate 1 (sample 3: see Figures 5 and 6) in which an organic resin is located around the interlayer connection conductor 22 was obtained by performing the same processing as sample 1, except that pressure and heat were applied for 30 seconds.

[0071] (Preparation of Sample 4) By performing the same processing as Sample 1, except that the amount of curing agent (amine-based) contained in the organic material (resin component) that becomes the organic resin base 21 of the organic resin base wiring layer 20 was 1.2 times that of Sample 1, a wiring substrate 1 (Sample 4: see Figure 7) having an outer peripheral region 22b with a higher proportion of particulate metal than the inner region 22a was obtained.

[0072] (Preparation of Sample 5) The same processing as Sample 4 was performed, except that a green sheet (silica powder was added at 10 parts by mass per 100 parts by mass of epoxy resin) harder than the material of the organic resin base 21 used for the organic resin base wiring layer 20 of Sample 4 was used. As a result, the interlayer connection conductors 220 before curing were deformed, and a wiring board 1 (Sample 5: see FIG. 8) was obtained having interlayer connection conductors 22 whose diameters at portions closer to the surface of the organic resin base wiring layer 20 were smaller than those at portions located at the center in the thickness direction of the organic resin base wiring layer 20. For the green sheet harder than the material of the organic resin base 21 of Sample 4, an organic material whose glass transition temperature was 20° C. higher than that of the organic material used for Sample 4 was used.

[0073] The prepared samples 1, 2, 3, 4, and 5 had a copper metallized film 120 as a surface conductor layer 12 on the surface of the ceramic substrate 11. The metallized film 120 had a surface conductor layer 12 protruding from the surface of the ceramic substrate 11, and protruded by a thickness close to the thickness of the surface conductor layer 12. In all of the samples (1 to 5), the first region 211 of the organic resin substrate 21 had a lower ratio of the total area of ​​voids than the second region 212, with a difference of 0.5% or more. In this case, voids with a diameter of 0.1 μm or more were extracted as voids.

[0074] Comparative Example: Preparation of Sample 6 A wiring board 1 was prepared in which the ceramic substrate wiring layer 10 and the organic resin substrate wiring layer 20 were reversed in the configuration of Sample 1.

[0075] (Preparation of Sample 7) A wiring substrate having a ceramic substrate 11 with a uniform density was also prepared as a comparative example by performing the same process as Sample 1, except that a ceramic substrate wiring layer 10 without a metallized film was used on the surface of the ceramic substrate 11. Sample 7 had the same total void area ratio in the portions corresponding to the first and second regions of the ceramic substrate insulating base. In this case, the ratios of the total void area were considered to be the same when they were within 1%.

[0076] 12 is a plan view showing a wiring board according to an experimental example. In the wiring boards 1A according to samples 1 to 7, the diameter of the interlayer connection conductors 22 was 100 μm, the spacing between adjacent interlayer connection conductors 22 was 50 μm, and a total of 100 interlayer connection conductors 22 were arranged in 10 rows and 10 columns. These interlayer connection conductors 22 were connected in series.

[0077] Temperature cycle test (the produced wiring board was mounted on the surface of an external circuit board (printed board) using solder, and the test sample was placed in a thermostatic chamber controlled at temperatures of -40°C and 125°C in an air atmosphere, with one cycle consisting of 15 minutes / 15 minutes, and repeated up to 2000 cycles).

[0078] In addition, the test sample was placed in a thermostatic chamber controlled at temperatures of -40°C and 150°C, and a maximum of 2,000 cycles were performed, with one cycle consisting of 30 minutes / 30 minutes. (The 150°C x 30 minutes / 30 minutes cycle was also prepared for both the 125°C x 15 minutes / 15 minutes cycle.)

[0079] (-40°C to 125°C): Samples 1 to 5 and 7 showed no cracks or other fractures at the connection points with the external circuit board even after 2000 cycles, but sample 6 showed fractures in multiple locations. These fractures were particularly concentrated in the four corners (four locations) of the peripheral arrangement.

[0080] (-40 to 150°C): Samples 1 to 5 and 7 showed no cracks or other fractures at the connection points with the external circuit board even after 2000 cycles, but sample 6 showed fractures in multiple locations, particularly concentrated at the four corners of the peripheral arrangement.

[0081] In the range of -40 to 150°C, the number of defective portions in sample 6 was twice as many (8 portions) as in the range of -40 to 125°C.

[0082] Next, a high-temperature, high-humidity bias test (HAST test) was performed on Samples 1 to 5 and 7 by applying a voltage of 5.5 V between adjacent interlayer connection conductors for 168 hours in an environment of 130°C and 85% Rh. The rate of decrease in insulation resistance was measured based on the value before the test. The results are shown in Figure 13.

[0083] The values ​​of the reduction rates shown in FIG. 13 are average values ​​of the four locations shown in FIG. 12 (between interlayer connection conductors 22-1 and 22-2, between 22-9 and 22-10, between 22-91 and 22-92, and between 22-99 and 22-100).

[0084] 13 is a diagram showing the evaluation results of the wiring boards according to the experimental example. As shown in FIG. 13, the effect of reducing the decrease in insulation resistance was confirmed in all of the wiring boards 1A according to samples 1 to 5 compared to the wiring board according to sample 7.

[0085] Furthermore, in all of the wiring boards 1 relating to samples 1 to 5, it was confirmed that the effect of reducing peeling between the interlayer connection conductors 22 and the organic resin base 21 after the temperature cycle test was confirmed compared to the wiring board relating to sample 7.

[0086] Furthermore, in all of the wiring boards 1 according to Samples 1 to 5, it was confirmed that, compared to the wiring board according to Sample 7, breakage of the electrical elements mounted on the interlayer connection conductors 22 was reduced.

[0087] The present disclosure has been described in detail above, but the present disclosure is not limited to the above-described embodiments, and various modifications, improvements, etc. are possible within the scope that does not deviate from the gist of the present disclosure.

[0088] In one embodiment, (1) the wiring board has a base and a conductor, the base is a laminate of a ceramic base wiring layer and an organic resin base wiring layer, the organic resin base wiring layer has an organic resin base as an insulating base, the ceramic base wiring layer has a ceramic base as an insulating base, the organic resin base has a higher thermal expansion coefficient than the ceramic base, when the surface of the laminate facing the ceramic base is defined as a first surface and the surface of the laminate facing the organic resin base is defined as a second surface, the first surface and the second surface are surfaces of the laminate facing opposite to each other, the conductor has a first terminal group and a second terminal group, the first terminal group is provided on the first surface of the laminate, and the second terminal group is provided on the second surface of the laminate, the first surface is a surface on which electrical elements are mounted, and the second surface is a surface for connecting to an external circuit board.

[0089] (2) In the wiring board of (1) above, when the surface located on the opposite side of the first surface of the ceramic base and in contact with the organic resin base is defined as a third surface, the ceramic base has a surface conductor layer on the third surface, the surface conductor layer protrudes from the third surface with a step of a predetermined thickness, the organic resin base has an interlayer connection conductor penetrating in the thickness direction, and the surface conductor layer and the interlayer connection conductor are electrically connected, the organic resin base has a first region and a second region, the first region is located on the surface conductor layer, and the second region may be located on a part of the organic resin base other than the first region.

[0090] (3) The wiring board of (2) above may have a coated conductor layer located on the surface conductor layer.

[0091] (4) In the wiring board of (2) or (3) above, the interlayer connection conductor may have a mixed region near the outer periphery in which a resin component is positioned in a band shape in the longitudinal direction of the interlayer connection conductor and in which a metal is mixed.

[0092] (5) In the wiring board of (4) above, the interlayer connection conductor may have an outer peripheral region and an inner region located inside the outer peripheral region, and the outer peripheral region may have a higher proportion of the particulate metal than the inner region.

[0093] (6) In any one of the wiring boards (2) to (5) above, the diameter of the interlayer connection conductor may be smaller at a portion closer to the surface of the organic resin base than at a portion located at the center of the thickness direction of the organic resin base.

[0094] (7) The wiring board of any one of (1) to (6) above may have a first surface wiring layer that is a surface wiring layer located on the first surface, and a second surface wiring layer that is a surface wiring layer located on the second surface, wherein both the first surface wiring layer and the second surface wiring layer have a circular shape in a planar view, and the diameter of the second surface wiring layer in a planar view may be larger than the diameter of the first surface wiring layer in a planar view.

[0095] In one embodiment, (8) an electric device includes the wiring board according to any one of (1) to (7) above, and an electric device mounted on the first surface.

[0096] In one embodiment, (9) an electric device structure includes the electric device according to (8) above, and an external circuit board connected to the second surface.

[0097] Further advantages and other aspects may readily occur to those skilled in the art. Therefore, the disclosure in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

[0098] REFERENCE SIGNS LIST 1 wiring board 2 electric element 3 electric device 4 external circuit board 5 electric device structure 10 ceramic substrate wiring layer 11 ceramic substrate 12 surface conductor layer 20 organic resin substrate wiring layer 21 organic resin substrate 22 interlayer connection conductor 22a inner region 22b outer peripheral region 30 coated conductor layer 211 first region 212 second region

Claims

1. A substrate and a conductor are included. the substrate is a laminate of a ceramic substrate wiring layer and an organic resin substrate wiring layer, the organic resin substrate wiring layer has an organic resin substrate as an insulating substrate, the ceramic substrate wiring layer has a ceramic substrate as an insulating substrate, the organic resin substrate has a higher thermal expansion coefficient than the ceramic substrate, a surface of the laminate facing the ceramic substrate is defined as a first surface, and a surface of the laminate facing the organic resin substrate is defined as a second surface, the first surface and the second surface of the laminate being surfaces facing opposite to each other; the conductor has a first group of terminals and a second group of terminals; the first terminal group is provided on the first surface of the laminate, the second terminal group is provided on the second surface of the laminate, the first surface is a mounting surface for an electric element, The second surface is a surface for connection to an external circuit board. Wiring board.

2. a surface of the ceramic base that is located opposite to the first surface and that is in contact with the organic resin base is defined as a third surface, and the ceramic base has a surface conductor layer on the third surface; the surface conductor layer protrudes from the third surface to have a step of a predetermined thickness, the organic resin base has an interlayer connection conductor penetrating in a thickness direction, the surface conductor layer and the interlayer connection conductor are electrically connected to each other, the organic resin base has a first region and a second region, the first region is located on a surface conductor layer; The second region is located on the organic resin base other than the first region. The wiring board according to claim 1 .

3. a coated conductor layer located on the surface conductor layer; The wiring board according to claim 2 .

4. The interlayer connection conductor has a mixed region in which a resin component is positioned in a band shape in the longitudinal direction of the interlayer connection conductor near the outer periphery and a metal is mixed therein. The wiring board according to claim 2 .

5. The interlayer connection conductor has an outer circumferential region and an inner region located inside the outer circumferential region, and the outer circumferential region has a higher proportion of the particulate metal than the inner region. The wiring board according to claim 4 .

6. The interlayer connection conductor has a diameter smaller at a portion located at the center in the thickness direction of the organic resin base than at a portion located near the surface of the organic resin base. The wiring board according to claim 2 .

7. a first surface wiring layer that is a surface wiring layer located on the first surface; a second surface wiring layer that is a surface wiring layer located on the second surface; and the first surface wiring layer and the second surface wiring layer each have a circular shape in a plan view, The diameter of the second surface wiring layer in plan view is larger than the diameter of the first surface wiring layer in plan view. The wiring board according to claim 1 .

8. A wiring board according to any one of claims 1 to 7; an electrical device mounted on the first surface; An electrical device comprising:

9. an electrical device according to claim 8; an external circuit board connected to the second surface; An electrical equipment structure comprising: