Electronic element mounting structure

Abstract

An electronic element mounting structure according to the present invention comprises an electronic element and an electronic element mounting substrate on which the electronic element is mounted. The electronic element mounting substrate includes: a substrate having a first main surface and a second main surface that is a surface on the opposite side from the first main surface; a first electronic element mounting part which is located on the first main surface and on which the electronic element is mounted; surface wiring that is located on the first main surface and electrically connected to the electronic element; and internal wiring that is at least partially located inside of the substrate and is capable of transmitting an electric signal input, via the surface wiring, from the electronic element. The substrate includes: a first base member that includes the first electronic element mounting part and has a ceramic material as a main component; and a second base member that includes the surface wiring and has an organic resin as a main component. The second base member is laminated on the first base member so as to surround the first electronic element mounting part in a plan view of the first main surface from a direction leading from the first main surface toward the second main surface.

Description

Electronic element mounting structure

[0001] The disclosed embodiments relate to an electronic device mounting structure.

[0002] 2. Description of the Related Art A wiring board has been proposed in which a plurality of circuit sections made of organic resin are laminated on a ceramic substrate.

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

[0004] According to one aspect of the present disclosure, there is provided an electronic element mounting structure, the electronic element mounting structure comprising: an electronic element; and an electronic element mounting substrate on which the electronic element is mounted, the electronic element mounting substrate having a substrate including a first main surface and a second main surface opposite to the first main surface, a first electronic element mounting portion located on the first main surface and on which the electronic element is mounted, surface wiring located on the first main surface and electrically connected to the electronic element, and internal wiring at least a portion of which is located inside the substrate and capable of transmitting an electrical signal input from the electronic element via the surface wiring; The electronic component mounting circuit may include a first substrate including a sub-element mounting portion and primarily composed of a ceramic material, and a second substrate including the surface wiring and primarily composed of an organic resin, wherein the second substrate is laminated on the first substrate so as to surround the first sub-element mounting portion when the first main surface is viewed in a plan view from the first main surface toward the second main surface, and the internal wiring may include a first internal wiring extending inside the first substrate and a second internal wiring extending inside the second substrate, and the second internal wiring may electrically connect the first internal wiring and the surface wiring.

[0005] 1 is an exploded perspective view showing an example of a wiring board according to a first embodiment. FIG. 2 is a perspective view showing an example of a wiring board according to the first embodiment. FIG. 3 is a cross-sectional view taken along line A-A in FIG. 2. FIG. 4 is a cross-sectional view taken along line B-B in FIG. 2. 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 a cross-sectional view showing an example of a wiring board according to a fourth embodiment. FIG. 7 is a cross-sectional view showing an example of a wiring board according to a fifth embodiment. FIG. 8 is a cross-sectional view showing an example of a wiring board according to a sixth embodiment. FIG. 9 is a cross-sectional view showing an example of a wiring board according to a seventh embodiment. FIG. 10 is a perspective view showing an example of a wiring board according to an eighth embodiment. FIG. 11 is a schematic cross-sectional view showing an example of an electronic element mounting structure according to an eighth embodiment. FIG. 12 is a schematic plan view of a first main surface of a wiring board according to an eighth embodiment. FIG. 13 is a schematic plan view of a second main surface of a wiring board according to an eighth embodiment. FIG. 14 is a cross-sectional view showing an example of a wiring board according to a ninth embodiment.

[0006] Hereinafter, embodiments for carrying out an electronic device mounting 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, the embodiments can be appropriately combined within the scope of not causing any contradiction in the processing content.

[0007] In the following, the same or similar components are denoted by the same reference numerals, and detailed description thereof will be omitted. Note that, in order to make the description easier to understand, in the drawings referred to below, expressions derived from an orthogonal coordinate system may be used, which defines mutually orthogonal X-axis, Y-axis, and Z-axis directions, with the positive Z-axis direction being the vertically upward direction.

[0008] A wiring board has been proposed in which multiple circuit sections made of organic resin are laminated on a ceramic substrate. However, when the wiring board is to be mounted with electronic elements, it may be required to improve the heat dissipation of the area where the electronic elements are mounted, depending on the application.

[0009] Therefore, there is a need for a technology that can solve the above problems and improve the heat dissipation performance of the area where electronic elements are mounted.

[0010] First Embodiment Fig. 1 is an exploded perspective view showing an example of a wiring board according to a first embodiment. Fig. 2 is a perspective view showing an example of a wiring board according to the first embodiment. Fig. 3 is a cross-sectional view taken along line A-A in Fig. 2. As shown in Figs. 1 to 3, a wiring board 1 according to the first embodiment has a first substrate 10 and a second substrate 20.

[0011] Here, the first substrate 10 has a base portion 11. The base portion 11 may have a flat plate-like shape. The outer shape of the base portion 11 may be, for example, rectangular. Here, a rectangular shape is one based on a square or a rectangle. The corners of the base portion 11 may have notches, and the base portion 11 does not have to be a perfect rectangle. Furthermore, if the first substrate 10 does not have a protrusion 12 described below, the base portion 11 may have a mounting surface 121 on which an electronic element can be mounted.

[0012] The second substrate 20 also has a flat plate shape and has a rectangular outer shape. The second substrate 20 is layered on the first substrate 10. In other words, the first substrate 10 and the second substrate 20 form a laminate. The second substrate 20 may have notches formed at the corners thereof, and may not be a perfect rectangle.

[0013] In this case, the first substrate 10 contains any one of a ceramic material, a metal material, a carbon material, and a composite of two or more of these materials, while the second substrate 20 contains an organic resin as a main component.

[0014] This wiring board 1 has copper foil wiring on the surface of a second substrate 20. This wiring board 1 is a laminated body in which a substrate (second substrate 20) made of organic resin, on which copper foil wiring can be easily formed, is laminated and integrated with a substrate (first substrate 10) having higher rigidity than the second substrate 20.

[0015] That is, this wiring board 1 is a structure in which the rigidity of the second base material 20 made of organic resin, which is easy to bond copper foil to, allowing for the formation of fine wiring, can be compensated for by the first base material 10. Thus, the wiring board 1 constituting one aspect of the first embodiment has high rigidity, and can realize finer wiring and narrower pitches.

[0016] Next, the wiring board 1 can also have the following configuration. First, when one surface of the base portion 11 is defined as a first surface 111, the first substrate 10 constituting the wiring board 1 has a convex portion 12 on the first surface 111. The convex portion 12 is disposed at the center of the first surface 111. In other words, it is preferable that the base portion 11 and the convex portion 12 are integral with each other.

[0017] The first substrate 10 may further have a protrusion 12 located on the base portion 11. In this case, the base portion 11 is flat.

[0018] When the first substrate 10 has a convex portion 12, the convex portion 12 is located on the first surface 111 of the base portion 11. The convex portion 12 is a structure located near the center of the first surface 111, away from the outer edge 110 of the first surface 111. The convex portion 12 has a mounting surface 121. In other words, the convex portion 12 can be said to have a structure in which only the mounting surface 121 protrudes from the first surface 111 of the base portion 11. The mounting surface 121 is the upper surface of the convex portion 12 on which an electronic element can be mounted. Here, the upper surface of the convex portion 12 is an expression resulting from the fact that the upper surface faces the positive direction of the Z axis, as shown in FIG. 1, for example. The mounting surface 121 may also be referred to as the upper surface when the wiring substrate 1 in FIG. 1 is turned upside down. In other words, the mounting surface 121 may also be referred to as the upper surface when the mounting surface 121 of the convex portion 12 faces the negative direction of the Z axis.

[0019] The first substrate 10 may be made of, for example, a ceramic material, a metal material, a carbon material, or a composite of two or more of these materials. Examples of ceramic materials include aluminum oxide sintered bodies, aluminum nitride sintered bodies, mullite sintered bodies, glass ceramic sintered bodies, crystallized glass in which crystalline components are precipitated in a glass matrix, and microcrystalline sintered bodies such as mica or aluminum titanate. Examples of metal materials include copper, silver, palladium, gold, platinum, aluminum, chromium, nickel, cadmium-lead, selenium, manganese, tin, vanadium, lithium, cobalt, and titanium. Examples of carbon materials include graphite.

[0020] The first substrate 10 may have the base portion 11 and the protruding portions 12 integrated together. For example, there may be no lamination interface between the base portion 11 and the protruding portions 12. Furthermore, no material other than the material constituting the first substrate 10, such as an adhesive, may be present between the base portion 11 and the protruding portions 12. If the first substrate 10 is made of a ceramic material, it is relatively easy to form the protruding portions 12.

[0021] The second substrate 20 is laminated on the first surface 111 of the first substrate 10. The second substrate 20 is flat and has a second surface 201 and a third surface 202 located at both ends in the thickness direction. The second surface 201 is the surface of the second substrate 20 facing the same direction as the mounting surface 121 of the first substrate 10. The third surface 202 is located on the opposite side to the second surface 201 and faces the first surface 111 of the first substrate 10.

[0022] The second base material 20 has a first through hole 21 penetrating through it in the thickness direction. With this configuration, the electronic element 9 and the protrusion 12 can be positioned inside the first through hole 21.

[0023] The second substrate 20 contains an organic resin as a main component. 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. The organic resin may be, for example, polytetrafluoroethylene (PTFE) or another fluororesin or a polyphenylene ether resin. The second substrate 20 may contain components other than the organic resin. Note that an optical component such as a lens or a cover may be positioned on the second substrate 20.

[0024] The first substrate 10 and the second substrate 20 are positioned such that the first through-hole 21 of the second substrate 20 fits into the protrusion 12 of the first substrate 10 .

[0025] For example, since the mounting surface 121 is located on the protrusion 12 formed on the first substrate 10, which has higher rigidity than the second substrate 20, the electronic element mounted on the mounting surface 121 is less likely to deform. Furthermore, if the electronic element mounted on the mounting surface 121 is an element that requires relatively high heat dissipation, using a ceramic material for the first substrate 10 can increase the heat dissipation of the first substrate 10 compared to the second substrate 20, so that the heat generated by the electronic element can be dissipated by the first substrate 10 relatively easily.

[0026] Furthermore, by using copper foil as the material for the wiring located on the second surface 201 of the second substrate 20, it is possible to make the wiring finer and with a narrower pitch. Furthermore, since the copper foil wiring is provided on the second substrate 20, which has a lower rigidity than the first substrate 10, the accumulation of residual stress is small. Therefore, according to this embodiment, it is possible to obtain a wiring board 1 that is less likely to deform and that allows for finer wiring and a narrower pitch, for example, with a line width of 50 μm or less and a pitch of 100 μm or less (line spacing of 50 μm).

[0027] 3, the mounting surface 121 of the convex portion 12 of the first substrate 10 and the second surface 201 located on the surface of the second substrate 20 may be flush with each other. When the second substrate 20 is placed on the first substrate 10, there is no portion of the second substrate 20 that protrudes above the convex portion 12 of the first substrate 10, which reduces the amount of deformation of the second substrate 20, for example. Furthermore, since deformation of the second substrate 20 is stopped by the convex portion 12, the entire second substrate 20 is less likely to deform.

[0028] If the mounting surface 121 and the second surface 201 are flush with each other, for example, when the mounting surface 121 and the second surface 201 are connected by wire bonding, the length of the bonding wire extending from the electronic element mounted on the mounting surface 121 to the wiring (element terminal) on the second surface 201 can be the shortest distance or a length close to this. This makes it possible to reduce the inductance of the bonding wire.

[0029] If the first substrate 10 is made of, for example, a highly rigid metallic material, it becomes easier to make the mounting surface 121 and the second surface 201 flush with each other.

[0030] Fig. 4 is a cross-sectional view taken along line BB in Fig. 2. The second substrate 20 has copper wiring 30 on its surface. The material of the wiring 30 may be, for example, copper foil.

[0031] The wiring 30 located on the second surface 201 may be embedded in a surface portion of the second substrate 20. For example, compared to a configuration in which the wiring 30 is disposed so as to protrude above the second surface 201 of the second substrate 20, a configuration in which the wiring 30 is embedded in the second substrate 20 makes it easier for the second substrate 20 and the wiring 30 to be subjected to a mutual restraining force. This makes the second substrate 20 less likely to deform.

[0032] In this way, in the wiring board 1, the second substrate 20 is attached to and stacked on the first substrate 10, which has greater rigidity than the second substrate 20, and thus the second substrate 20 is constrained by the first substrate 10. The second substrate 20 is also constrained by the wiring 30 formed on its surface. Furthermore, the second substrate 20 is also constrained by the convex portions 12 of the first substrate 10. The regions of the second substrate 20 close to the convex portions 12 are more susceptible to a constraining force in the planar direction than the peripheral portions away from the convex portions 12.

[0033] Furthermore, the front surface 301 of the wiring 30 may be flush with the second surface 201, which is the surface of the second substrate 20. This makes the second substrate 20 even less susceptible to deformation. Here, the front surface 301 of the wiring 30 refers to the surface of the wiring 30 that is exposed from the second substrate 20 when the second substrate 20 is viewed in plan from a position above it.

[0034] 4 can be produced by, for example, transferring and pressurizing a wiring material made of copper foil that has been patterned in advance on a PET film onto a ceramic green sheet that will become the first substrate 10. If necessary, heating may be performed simultaneously with pressing.

[0035] Second Embodiment Fig. 5 is a cross-sectional view showing an example of a wiring board according to a second embodiment. Fig. 5 does not show the entire wiring board 1, but only a portion near the periphery of the protrusion 12 provided on the first base material 10. As shown in Fig. 5, the second surface 201 may be closer to the first surface 111 than the mounting surface 121.

[0036] Since the thickness of the second substrate 20 is thinner than the thickness of the first substrate 10 where the convex portion 12 is located, the second substrate 20 is more easily restrained by the convex portion 12 and the base portion 11 of the first substrate 10, making it less susceptible to deformation.

[0037] Furthermore, because the protrusions 12 protrude beyond the second surface 201 of the second substrate 20, when an electronic element is mounted on the mounting surface 121, for example, when the protrusions 12 are recognized by a camera, part of the side surface of the protrusions 12 becomes easily visible along with the ridge lines that form the edges of the mounting surface of the protrusions 12. Therefore, the wiring board 1 according to this embodiment makes it easy to recognize images, for example.

[0038] 5 shows a configuration in which the second substrate 20 has the same thickness over the entire area of ​​the portion that contacts the first surface 111 of the first substrate 10, but this is not limiting, and for example, at least a portion of the second substrate 20 that is close to the convex portion 12 may be closer to the first surface 111 than the mounting surface 121. When the second substrate 20 has the same thickness, for example, bias in deformation of the second substrate 20 and variation in the amount of deformation are reduced.

[0039] The configuration shown in FIG. 5 can be produced, for example, by using a rubber mold or the like on the upper side of the laminator, which is easily deformed when it comes into contact with the product.

[0040] 6 is a cross-sectional view showing an example of a wiring board according to a third embodiment. As shown in Fig. 6, the surface (second surface 201) of the second base material 20, which is a portion of the surface (second surface 201) close to the protrusion 12, may be located higher than the upper surface (mounting surface 121) of the protrusion 12. In other words, the second surface 201 may be located at a greater distance from the first surface 111 than the mounting surface 121.

[0041] Since the second substrate 20 is thick and the second surface 201 of the second substrate 20 is farther from the first surface 111 than the mounting surface 121 of the convex portion 12, the second substrate 20 will have, for example, a portion that protrudes above the mounting surface 121 of the convex portion 12.

[0042] The second substrate 20 is configured to have, in the thickness direction of the first substrate, a portion that is close to the first surface 111 of the first substrate 10 and is easily restrained by the first substrate 10, and a portion that is far from the first surface 111 or the mounting surface 121 of the convex portion 12 and is not easily restrained by the first substrate 10.

[0043] The portion of the second base material 20 above the mounting surface 121 of the protrusion 12 acts as a part that relieves the stress that occurs when, for example, a bending load is applied to the wiring board 1, and can withstand both tensile stress and compressive stress. As a result, for example, even when a mechanical load is applied to the wiring board 1, damage to the board material and wiring is less likely to occur.

[0044] Furthermore, in this configuration, for example, the bonding wire (not shown) that connects between the electronic element (not shown) mounted on the mounting surface 121 and the connection terminal (not shown) formed on the second substrate 20 can be made linear, which leads to a reduction in inductance.

[0045] 6 shows a configuration in which the second substrate 20 has the same thickness over the entire area of ​​the portion that contacts the first surface 111 of the first substrate 10, but this is not limiting, and for example, at least a portion of the second substrate 20 that is close to the convex portion 12 may be further away from the first surface 111 than the mounting surface 121. When the second substrate 20 has the same thickness, for example, bias in deformation of the second substrate 20 and variation in the amount of deformation are reduced.

[0046] The structure shown in FIG. 6 can be produced by using, for example, an inverted convex mold or a rubber mold.

[0047] 3 , when the surface of the convex portion 12 constituting the first base material 10 that faces the same direction as the first surface 111 of the first base material 10 is defined as the upper surface (mounting surface 121), the convex portion 12 has a side surface 122 that intersects with the upper surface (mounting surface 121) and a ridge portion 123A that connects the side surface 122 to the upper surface (mounting surface 121). Preferably, the second base material 20 has an inner wall 20A of the second base material 20 that faces the first through hole 21 in contact with the convex portion 12 from the side surface 122 to the ridge portion 123A.

[0048] FIG. 7 is a cross-sectional view showing an example of a wiring board according to the fourth embodiment. In the wiring board 1 shown in FIG. 7, the ridge portion 123A connecting the side surface 122 of the protrusion 12 to the upper surface (mounting surface 121) has a so-called chamfered shape. In other words, as can be seen from the cross-sectional view shown in FIG. 7, in this wiring board 1, the corner where the side surface 122 of the protrusion 12 intersects with the upper surface (mounting surface 121) is rounded. In other words, in the wiring board 1 shown in FIG. 7, the surface of the corner (corresponding to the ridge portion 123A) connecting the side surface 122 of the protrusion 12 to the upper surface (mounting surface 121) is curved.

[0049] In Fig. 7, the ridge portion 123A is disposed so as to extend in the direction into the plane of the paper in Fig. 7. The rounded corner where the side surface 122 and the upper surface (mounting surface 121) of the protrusion 12 intersect is hereinafter referred to as a first R-chamfered portion 123. The curved surface of the corner connecting the side surface 122 of the protrusion 12 to the upper surface (mounting surface 121) is hereinafter referred to as a first R-chamfered portion 123.

[0050] 7 , the protrusion 12 may have a side surface 122 and a first R-chamfered portion 123. The side surface 122 is a surface that intersects with the mounting surface 121. The first R-chamfered portion 123 is located on the ridge where the side surface 122 and the mounting surface 121 intersect, and is a portion that is curved in a convex shape.

[0051] In the second substrate 20, the inner wall of the first through hole 21 may be in contact with the side surface 122 of the convex portion 12 from the first R-chamfered portion 123. Since the convex portion 12 of the first substrate 10 has the first R-chamfered portion 123, the contact area between the inner wall of the first through hole 21 of the second substrate 20 and the first substrate 10 is larger than when the ridge portion of the convex portion 12 is simply angular and does not have the first R-chamfered portion 123. This increases the fixing force of the second substrate 20 to the first substrate 10, making it less likely to deform. Therefore, according to this embodiment, for example, the surface portion of the second substrate 20 on the mounting surface 121 side is less likely to peel off.

[0052] Fifth Embodiment FIG. 8 is a cross-sectional view showing an example of a wiring board according to a fifth embodiment.

[0053] 3, following on from FIG. 7, the wiring board 1 has a corner 124A where the first surface 111 of the first substrate 10 and the side surface 122 of the protrusion 12 are connected. The second substrate 20 is preferably in contact with the corner 124A.

[0054] 8, corners 124A connecting first surface 111 to side surfaces 122 of protrusions 12 form a concavely curved shape from first surface 111 to side surfaces 122 of protrusions 12. In other words, in this case, as can be seen from the cross-sectional view shown in FIG. 8, corners 124A where first surface 111 and side surfaces 122 of protrusions 12 intersect are rounded in this wiring board 1.

[0055] In Fig. 8, corner portion 124A is disposed so as to extend in the direction into the paper of Fig. 8. The concavely rounded portion of corner portion 124A where first surface 111 and side surface 122 of protrusion 12 intersect is hereinafter referred to as second R-chamfered portion 124.

[0056] 8 , the protrusion 12 may have a side surface 122 and a second R-chamfered portion 124. The side surface 122 is a surface that intersects with the mounting surface 121. The second R-chamfered portion 124 is located at a corner where the side surface 122 and the first surface 111 intersect, and is a concavely curved portion.

[0057] In the second substrate 20, the inner wall of the first through hole 21 may be in contact with the side surface 122 of the convex portion 12 from the second R-chamfered portion 124. Since the convex portion 12 of the first substrate 10 has the second R-chamfered portion 124, the contact area between the inner wall of the first through hole 21 of the second substrate 20 and the first substrate 10 is larger than when the corners of the convex portion 12 are simply angular and do not have the second R-chamfered portion 124. This increases the fixing force of the second substrate 20 to the first substrate 10, making the second substrate 20 less likely to deform.

[0058] The first substrate 10 shown in FIGS. 7 and 8 can be formed, for example, by using a green sheet made of a ceramic sintered body formed using a dedicated mold.

[0059] Sixth Embodiment Fig. 9 is a cross-sectional view showing an example of a wiring board according to a sixth embodiment. As shown in Fig. 9, the protrusion 12 may have a side surface 122, a first R-chamfered portion 123, and a second R-chamfered portion 124. The side surface 122 is a surface that intersects with the mounting surface 121. The first R-chamfered portion 123 is located at the ridge where the side surface 122 and the mounting surface 121 intersect, and is a convexly curved portion. The second R-chamfered portion 124 is located at the corner where the side surface 122 and the first surface 111 intersect, and is a concavely curved portion.

[0060] In the second base material 20 , the inner wall of the first through hole 21 may be in contact with the side surface 122 of the protrusion 12 from the first R-chamfered portion 123 and the second R-chamfered portion 124 .

[0061] In the first substrate 10, the convex portions 12 have the first R-chamfered portions 123, so the contact area between the inner walls of the first through holes 21 in the second substrate 20 and the first substrate 10 is larger than when the ridge portions of the convex portions 12 are simply angular and do not have the first R-chamfered portions 123. In addition, in the first substrate 10, the convex portions 12 have the second R-chamfered portions 124, so the contact area between the inner walls of the first through holes 21 in the second substrate 20 and the first substrate 10 is larger than when the corners of the convex portions 12 are simply angular and do not have the second R-chamfered portions 124. This increases the fixing force of the second substrate 20 to the first substrate 10, making it less likely to deform.

[0062] 10 is a cross-sectional view showing an example of a wiring board according to a seventh embodiment. As shown in Fig. 10, the protrusion 12 has a side surface 122 that intersects with the mounting surface 121. In this case, the side surface 122 may be spaced apart from an inner wall facing the first through hole 21 of the second substrate 20.

[0063] For example, even when a highly heat-generating electronic element is mounted on the mounting surface 121 of the protrusion 12, heat from the electronic element is less likely to be transferred to the second substrate 20 that handles the wiring portion, making it possible to suppress changes in the resistance of the wiring portion due to temperature. Furthermore, since the amount of deformation due to thermal expansion of the second substrate 20 can be reduced, it is possible to stabilize the transmission characteristics of the wiring 30 (see FIG. 4 ). Furthermore, even if, for example, resin used to mount an electronic element on the mounting surface 121 flows and spreads outward from the mounting surface 121, the resin is less likely to reach the second surface 201 of the second substrate 20, making it less likely that poor finish (appearance) of the wiring board 1 will occur.

[0064] 10 can be produced, for example, by forming holes (first through holes) larger than the protrusions 12 in advance in the organic resin that is the material of the second substrate 20, and maintaining this gap by elastic pressing. Alternatively, before the second substrate 20 is superimposed on the first substrate 10, a silicone-based mold release agent may be applied to the side surfaces 122 of the protrusions 12 of the first substrate 10, which causes the second substrate 20 to shrink more than the first substrate 10 when cooled after being pressurized and heated.

[0065] Eighth Embodiment FIG. 11 is a perspective view showing an example of a wiring board 1 according to an eighth embodiment. FIG. 12 is a schematic cross-sectional view showing an example of an electronic device mounting structure 8 according to the eighth embodiment. FIG. 12 is a schematic cross-sectional view of the electronic device mounting structure 8 taken along the line A-A in FIG. 11 . As shown in FIG. 12 , the electronic device mounting structure 8 may include a wiring board 1 serving as a substrate for mounting electronic devices, an electronic device 9 mounted on the wiring board 1, and a connection target 800 attached to the wiring board 1. The connection target 800 may be any of a variety of substrates, such as a wiring board including internal wiring, a printed circuit board such as a motherboard, or an interposer capable of electrical continuity on both sides. Furthermore, the connection target 800 is not limited to a substrate and may be, for example, a connector terminal or a wiring cable. In this embodiment, the connection target 800 is a motherboard. Hereinafter, identical or similar components will be designated by the same reference numerals, and detailed description thereof will be omitted.

[0066] The electronic element 9 may be, for example, an element for a sensor, more specifically, an electronic element for an image sensor. The electronic element is not limited to an element for a sensor, and may be any other electronic element.

[0067] The wiring board 1 may have a substrate 100 including a first substrate 10 primarily composed of a ceramic material and a second substrate 20 primarily composed of an organic resin. The primary component may be, for example, a substance that accounts for 80% or more of the content of the substrate. In this embodiment, the first substrate 10 and the second substrate 20 may be stacked. Hereinafter, the direction in which the first substrate 10 and the second substrate 20 are stacked will be referred to as the stacking direction or Z direction. In addition, in FIG. 11 , the stacking direction is indicated as the Z direction. In FIG. 11 , a first direction intersecting the Z direction is indicated as the X direction. In addition, in FIG. 11 , a direction intersecting the Z direction and the X direction is indicated as the Y direction.

[0068] The wiring substrate 1 may have a first main surface 101 and a second main surface 102. The first main surface 101 may be a surface including a mounting surface 121 and a second surface 201. The second main surface 102 may be a surface opposite to the first main surface 101 in the Z direction. In other words, the direction from the first main surface 101 toward the second main surface 102 may be along the Z direction.

[0069] The wiring board 1 may have a first electronic element mounting portion 81 and wiring 30 as surface wiring, each located on the first main surface 101. The wiring board 1 may also have internal wiring 32 located inside the board 100 and external connection electrodes 34 located on the second main surface 102. The first electronic element mounting portion 81 may be a region where an electronic element 9 is mounted. The wiring 30 may be electrically connected to the electronic element 9. The internal wiring 32 may electrically connect the wiring 30 and the external connection electrodes 34. The external connection electrodes 34 may be electrically connected to a connection target 800. The internal wiring 32 may be electrically connected to the electronic element 9 via the wiring 30 and may be able to transmit an electrical signal input from the electronic element 9 via the wiring 30 to the external connection electrodes 34. In this embodiment, the wiring 30 may be electrically connected to the electronic element 9 by a bonding wire 900.

[0070] The first electronic element mounting portion 81 may be at least a part of the mounting surface 121. The first electronic element mounting portion 81 is thermally connected to the electronic element 9. The first electronic element mounting portion 81 and the electronic element 9 may be bonded using a bonding material having a higher thermal conductivity than the organic resin used in the second base material 20. The bonding material may be, for example, an inorganic bonding material such as a solder material, a brazing material, or a bonding material containing silver particles for silver particle sintering bonding. The bonding material may also be, for example, an organic bonding material such as an organic adhesive containing a metal such as copper or silver or a ceramic material such as aluminum nitride or aluminum oxide as a filler. The organic adhesive may contain various organic components such as epoxy-based, acrylic-based, imide-based, urethane-based, or silicone-based. In this embodiment, heat generated from the electronic element 9 is transferred from the first electronic element mounting portion 81 to the inside of the first base material 10. Therefore, the second base material 20 is not necessarily included in the heat transfer path from the electronic element 9 to the first base material 10.

[0071] With this configuration, heat generated in the electronic element 9 is easily dissipated in the first substrate 10, thereby reducing the possibility of heat being transferred to the connection object 800. Therefore, for example, if the main component of the connection object 800 is organic resin and the main component of the first substrate 10 is ceramic, the first substrate 10, which is thermally connected to the electronic element 9, can efficiently dissipate heat generated in the electronic element 9, thereby reducing the possibility of the connection object 800 warping due to the heat. Note that the electronic element 9 may be thermally connected to the second substrate 20 in addition to the first electronic element mounting portion 81. If the electronic element 9 is thermally connected to the second substrate 20, the effect of the heat generated in the electronic element 9 on the connection object 800 can be further reduced.

[0072] The first substrate 10 may include a base portion 11 and a protruding portion 12. When viewed from the Z direction, the protruding portion 12 may be located inside the base portion 11. Furthermore, when viewed from a direction intersecting the Z direction, for example, the X direction in FIG. 11 , the protruding portion 12 may protrude from the base portion 11 in the Z direction. The protruding portion 12 may include a mounting surface 121 at an end opposite the base portion 11 in the Z direction. The first substrate 10 may have a higher thermal conductivity than the second substrate 20. Furthermore, the first substrate 10 may have a higher rigidity than the second substrate 20. Furthermore, the first substrate 10 may have a higher thermal conductivity and a higher rigidity than the connection target 800.

[0073] The second substrate 20 may be frame-shaped and include a first through-hole 21 that opens in the Z direction. The second substrate 20 may be bonded to the base portion 11. More specifically, a first surface 111, which is an end surface of the base portion 11 in the Z direction, may be bonded to a third surface 202 of the second substrate 20 that faces the first surface 111. The second substrate 20 may surround the periphery of the convex portion 12 when viewed from the Z direction. At least a portion of the convex portion 12 may be located inside the first through-hole 21. In other words, the second substrate 20 may overlap at least a portion of the convex portion 12 when viewed from a direction intersecting the Z direction, for example, the X direction in FIG. 11 . In this case, it is easier to reduce the height difference between the first substrate 10 and the second substrate 20 in the Z direction compared to when the convex portion 12 is not present.

[0074] The first substrate 10 may include, as a ceramic material, an aluminum oxide sintered body, an aluminum nitride sintered body, a silicon nitride sintered body, or a glass ceramic sintered body containing a glass-based material, known as low-temperature co-fired ceramics (LTCC). The first substrate 10 may be a laminate in which sheet-like members primarily composed of ceramic materials are stacked in the Z direction. When the first substrate 10 is made of an aluminum oxide sintered body, the rigidity of the first substrate 10 is more easily improved than when other ceramic materials are used. Furthermore, when the first substrate 10 is made of an aluminum nitride sintered body, the thermal conductivity of the first substrate 10 is more easily improved than when other ceramic materials are used. Furthermore, when the first substrate 10 is made of a silicon nitride sintered body, the toughness of the first substrate 10 is more easily improved than when other ceramic materials are used. When LTCC is used for the first substrate 10, the firing temperature of the first substrate 10 is lower than when other ceramic materials are used, thereby increasing the freedom to select components other than the ceramic material.

[0075] The second base material 20 may be made of an organic resin such as an epoxy resin, an acrylic resin, a polycarbonate resin, a polyimide resin, an olefin resin, or a polyphenylene resin. The organic resin may include, for example, polytetrafluoroethylene (PTFE) or other fluororesins or polyphenylene ether resins.

[0076] The first substrate 10 and the second substrate 20 may be bonded together by the properties of the components contained in the second substrate 20. In other words, there may be no bonding layer made of an adhesive or bonding material between the first substrate 10 and the second substrate 20. Bonding by the properties of the components contained in the second substrate 20 itself may be bonding by a crosslinking reaction of an organic resin or bonding by an anchor effect, for example.

[0077] The wiring 30 may be located on the second substrate 20 on the first main surface 101. When viewed from the Z direction, the wiring 30 may be located so as to sandwich the protrusion 12. The internal wiring 32 may have a first internal wiring 321 and a second internal wiring 322. The first internal wiring 321 may be a wiring extending inside the first substrate 10. The second internal wiring 322 may be a wiring extending inside the second substrate 20. The first internal wiring 321 may electrically connect the external connection electrode 34 and the second internal wiring 322. The second internal wiring 322 may electrically connect the first internal wiring 321 and the wiring 30. In this embodiment, the first internal wiring 321 extends from the first surface 111 to the second main surface 102 in the base portion 11. Therefore, the internal wiring 32 extends through the first surface 111, which is the bonding surface between the first substrate 10 and the second substrate 20.

[0078] The first internal wiring 321 may include a first via conductor 321A that penetrates the ceramic layer 105 of the first base material 10, and a first interlayer wiring 321B that extends between two adjacent ceramic layers 105 in the Z direction. A portion of the first interlayer wiring 321B may extend in the Z direction from a position overlapping with the second base material 20 to a position overlapping with the protrusion 12. The first interlayer wiring 321B may be formed, for example, by a metallized pattern.

[0079] The second internal wiring 322 may include a second via conductor 322A that penetrates the organic resin layer 205 of the second substrate 20 and a second interlayer wiring 322B that extends between two organic resin layers 205 adjacent in the Z direction.

[0080] The first internal wiring 321 and the second internal wiring 322 may contain different metals. For example, the first internal wiring 321 may contain a metal with a higher melting point than the metal used for the second internal wiring 322. In this case, the firing temperature of the first substrate 10 can be more easily adjusted than when the melting point of the metal used for the first internal wiring 321 is lower than the melting point of the metal used for the second internal wiring 322. The second internal wiring 322 may contain a metal with a higher conductivity than the metal used for the first internal wiring 321. In this case, heat generation in the second internal wiring 322 due to electrical resistance can be reduced compared to when the conductivity of the metal used for the second internal wiring 322 is lower than the conductivity of the metal used for the first internal wiring 321. The first internal wiring 321 may contain, for example, molybdenum or tungsten as a metal with a high melting point. The second internal wiring 322 may contain, for example, copper or silver as a metal with a high conductivity.

[0081] FIG. 13 is a schematic plan view of the first main surface 101 of the wiring board 1. FIG. 14 is a schematic plan view of the second main surface 102 of the wiring board 1. As shown in FIGS. 13 and 14 , the distance d1 between two wirings 30 on the first main surface 101 may be smaller than the distance d2 between two external connection electrodes 34 on the second main surface 102. The density of the wirings 30 on the second substrate 20 may be smaller than the density of the external connection electrodes 34 on the first substrate 10. This allows the area on the first main surface 101 where the wirings 30 are located to be smaller, thereby allowing the first electronic element mounting portion 81 to be larger. This allows the electronic element mounting structure 8 to employ a larger element as the electronic element 9. Furthermore, because the distance d1 is smaller than the distance d2, the wiring board 1 can also function as an interposer that electrically connects the connection target 800 and the electronic element 9.

[0082] In this embodiment, the first electronic element mounting portion 81 is provided on the first substrate 10, which has a higher thermal conductivity than the second substrate 20. In this case, the wiring board 1 can efficiently transfer heat transmitted from the electronic elements 9, which are heat sources. This allows the wiring board 1 to more efficiently dissipate heat. This reduces the need for control to suppress heat generation from the electronic elements 9 or for limiting power. Furthermore, since the need for a separate cooling means is reduced, the entire device including the wiring board 1 can be made smaller.

[0083] In this embodiment, the electronic element 9 and the wiring 30 are electrically connected by a bonding wire 900. This makes it easy to separate the electronic element 9, which is a heat source, from the second substrate 20, which has a lower thermal conductivity than the first substrate 10. This reduces the transfer of heat generated from the electronic element 9 to the second substrate 20. Furthermore, since the bonding wire 900 can be attached after the electronic element 9 is fixed to the first electronic element mounting portion 81 using solder or the like, it is easy to thermally connect the electronic element 9 and the first substrate 10.

[0084] The electronic element mounting substrate 100 of this embodiment has the same or similar configuration as the above-described embodiment, and therefore provides the same or similar effects as the above-described embodiment.

[0085] 15 is a cross-sectional view showing an example of a wiring board according to a ninth embodiment, the first substrate 10 may not have a convex portion 12, and the electronic element 9 may be mounted on a mounting surface 121 located on the first surface 111. Furthermore, the height of the electronic element 9 may be lower than the height of the second substrate 20. Furthermore, an optical component such as a lens or a cover may be located on the second substrate 20.

[0086] Furthermore, the wiring board 1 may include a third substrate 40, which is primarily made of the same or similar organic resin as the second substrate 20, located on the back surface 112 opposite the first surface 111 of the first substrate 10. The third substrate 40 may also have a second through hole 41. This allows first electronic element mounting sections 81 to be formed on both surfaces of the wiring board 1. As shown in FIG. 15 , the first through hole 21 and the second through hole 41 do not need to have the same size. The sizes of the first through hole 21 and the second through hole 41 can be changed as appropriate depending on the size, number, and type of electronic element 9 to be located in the first through hole 21 and the second through hole 41.

[0087] In this case, one or more electronic elements 9 different from the electronic elements 9 mounted on the mounting surface 121 may be mounted on the rear surface 112 of the first substrate 10. In this case, the electronic elements 9 mounted on the rear surface 112 may be, for example, an amplifier, a capacitor, a thermistor, an integrated circuit, or a combination of these.

[0088] Furthermore, the third base material 40 may have wiring 30 on the surface and inside thereof. The wiring 30 located on the third base material 40 may be electrically connected to the connection target 800.

[0089] (Other Embodiments) In the above embodiment, the first substrate 10 has the protrusion 12, but this is not limiting. The first substrate 10 does not have to have the protrusion 12. In this case, for example, a region of the first substrate 10 surrounded by the second substrate 20 may function as the first electronic element mounting portion 81.

[0090] In the above embodiment, the electronic element 9 and the wiring 30 are connected by the bonding wire 900, but this is not limiting. For example, the electronic element 9 may be connected to the wiring 30 by flip-chip mounting without using the bonding wire 900. Even in this case, the first electronic element mounting portion 81 and the electronic element 9 may be thermally connected by solder or the like.

[0091] In the above embodiment, the second substrate 20 is frame-shaped, but is not limited thereto. The second substrate 20 may have a structure that surrounds the first electronic element mounting portion 81, and may be U-shaped, or may be provided in pairs at the ends of the first substrate 10 in the X direction or the Y direction.

[0092] In the above embodiment, the bonding material used to bond the first electronic element mounting portion 81 and the electronic element 9 is a bonding material with a higher thermal conductivity than the organic resin used in the second base material 20, but is not limited to this. For example, the bonding material may have a thermal conductivity equal to or lower than that of the organic resin. Even in this case, the wiring board 1 can more efficiently transfer heat transferred from the electronic element 9, which is a heat source, compared to when the first base material 10 including the first electronic element mounting portion 81 is made of an organic resin.

[0093] In each of the above-described embodiments, the first substrate 10 may have a conductor. The conductor may be, for example, a via conductor extending in the thickness direction of the first substrate 10, or a wiring or pad formed on at least one of the surface and the interior of the first substrate 10. When the first substrate 10 has such a configuration, the material of the first substrate 10 may be, for example, a ceramic material.

[0094] Although the present disclosure has been described in detail above, the present disclosure is not limited to the above-described embodiments, and various modifications, improvements, etc. are possible within the scope of the gist of the present disclosure. In addition, the respective embodiments can also be combined.

[0095] In one embodiment, (1) an electronic element mounting structure includes an electronic element and an electronic element mounting substrate on which the electronic element is mounted, the electronic element mounting substrate including: a substrate including a first main surface and a second main surface opposite to the first main surface; a first electronic element mounting portion located on the first main surface and on which the electronic element is mounted; surface wiring located on the first main surface and electrically connected to the electronic element; and internal wiring, at least a portion of which is located inside the substrate and capable of transmitting an electrical signal input from the electronic element via the surface wiring; the substrate includes: a first base material including the first electronic element mounting portion and made primarily of a ceramic material; and a second base material including the surface wiring and made primarily of an organic resin, the second base material being laminated on the first base material so as to surround the first electronic element mounting portion when the first main surface is viewed in a plan view from the direction from the first main surface toward the second main surface; and the internal wiring includes: first internal wiring extending inside the first base material and a second internal wiring extending inside the second base material, the second internal wiring electrically connecting the first internal wiring and the surface wiring.

[0096] (2) In the electronic element mounting structure of (1) above, the first internal wiring and the second internal wiring may contain different metals, the melting point of the metal contained in the first internal wiring may be higher than the melting point of the metal contained in the second internal wiring, and the conductivity of the metal contained in the second internal wiring may be higher than the conductivity of the metal contained in the first internal wiring.

[0097] (3) The electronic element mounting structure of (1) or (2) above may further include a connection object attached to the second main surface and electrically connected to the electronic element via the electronic element mounting substrate, and the substrate may have an external connection electrode located on the second main surface and electrically connecting the surface wiring and the connection object via the internal wiring.

[0098] (4) In any one of the electronic element mounting structures (1) to (3) above, the first substrate has a base portion and a convex portion that protrudes from the base portion in the stacking direction of the first substrate and the second substrate and includes the first electronic element mounting portion, the second substrate has a first through hole that penetrates in the stacking direction and is stacked on the base portion, and at least a portion of the convex portion may be located inside the first through hole.

[0099] (5) In the electronic element mounting structure of any one of (1) to (4) above, the electronic element and the surface wiring may be electrically connected via bonding wires.

[0100] 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.

[0101] REFERENCE SIGNS LIST 1 Wiring board (an example of a substrate for mounting electronic elements) 8 Electronic element mounting structure 9 Electronic element 10 First substrate 11 Base portion 12 Convex portion 20 Second substrate 21 First through hole 30 Wiring (an example of surface wiring) 32 Internal wiring 34 External connection electrode 40 Third substrate 41 Second through hole 81 First electronic element mounting portion 100 Substrate 101 First main surface 102 Second main surface 105 Ceramic layer 111 First surface 112 Back surface 121 Mounting surface 122 Side surface 123 First R-chamfered portion 124 Second R-chamfered portion 201 Second surface 202 Third surface 205 Organic resin layer 321 First internal wiring 321A First via conductor 321B First interlayer wiring 322 Second internal wiring 322A Second via conductor 322B Second interlayer wiring 800 Connection object 900 Bonding wire

Claims

1. A semiconductor device comprising: an electronic element; and an electronic element mounting substrate on which the electronic element is mounted, the electronic element mounting substrate comprising: a substrate including a first main surface and a second main surface opposite to the first main surface; a first electronic element mounting portion located on the first main surface and on which the electronic element is mounted; surface wiring located on the first main surface and electrically connected to the electronic element; and internal wiring, at least a portion of which is located inside the substrate and capable of transmitting an electrical signal input from the electronic element via the surface wiring; the substrate comprises: a first base material including the first electronic element mounting portion and made primarily of a ceramic material; and a second base material including the surface wiring and made primarily of an organic resin, the second base material being laminated on the first base material so as to surround the first electronic element mounting portion when the first main surface is viewed in plan from the direction from the first main surface toward the second main surface, and the internal wiring comprises: a first internal wiring extending inside the first base material; and a second internal wiring extending inside the second base material, the second internal wiring electrically connects the first internal wiring and the surface wiring.

2. The electronic element packaging structure described in claim 1, wherein the first internal wiring and the second internal wiring contain different metals, the melting point of the metal contained in the first internal wiring is higher than the melting point of the metal contained in the second internal wiring, and the conductivity of the metal contained in the second internal wiring is higher than the conductivity of the metal contained in the first internal wiring.

3. The electronic element mounting structure according to claim 1 or 2, further comprising a connection object attached to the second main surface and electrically connected to the electronic element via the electronic element mounting substrate, the substrate having an external connection electrode located on the second main surface and electrically connecting the surface wiring and the connection object via the internal wiring.

4. An electronic element mounting structure as described in any one of claims 1 to 3, wherein the first substrate has a base portion and a convex portion that protrudes from the base portion in the stacking direction of the first substrate and the second substrate and includes the first electronic element mounting portion, the second substrate has a first through hole penetrating in the stacking direction and is stacked on the base portion, and at least a portion of the convex portion is located inside the first through hole.

5. The electronic element mounting structure according to any one of claims 1 to 4, wherein the electronic element and the surface wiring are electrically connected via bonding wires.

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