WO2004112129A1

WO2004112129A1 - Electronic device

Info

Publication number: WO2004112129A1
Application number: PCT/JP2004/008458
Authority: WO
Inventors: Takehide Yokozuka; Masahide Harada; Shiro Yamashita; Kaoru Uchiyama; Syuuji Eguchi; Masahiko Asano; Koji Sato; Isamu Yoshida
Original assignee: Hitachi, Ltd.
Priority date: 2003-06-16
Filing date: 2004-06-16
Publication date: 2004-12-23
Also published as: JP2005005629A; JP4218434B2

Abstract

An object is to improve the heat radiation property of an electronic device, and particularly to improve the heat radiation property of an electronic device using an interposer substrate. The following construction is employed for an electronic device having a box and an electronic substrate. The electronic substrate comprises a first circuit board having electronic parts mounted thereon, and a second circuit board electrically connected to the first circuit board. The second circuit board of the electronic substrate is fixed to the box in a space where the first and second circuit boards do not become superposed on each other.

Description

Technical field

The present invention relates to an electronic device that requires a high heat dissipation structure, such as a electronic unit. Background art

[0002] Normally, a thermal cycle test is performed on an electronic device before shipment. Especially Ming

, ECUs and other in-vehicle electronic control devices

It is required that the temperature inside the vehicle changes greatly and that it meets the specifications that can withstand the heat cycle in a wide temperature range (normally -40 degrees to 120 degrees: JASOD001, the general rule for environmental testing of automotive electronic devices). Nowadays, there is a tendency to place ECUs closer to the engine, so that the specifications at the upper end of this temperature range tend to be higher. Therefore, the on-vehicle electronic device is required to have a higher heat radiation property than a general electronic device.

[0003] In recent years, electronic devices have adopted a structure in which electronic components such as semiconductor devices are mounted on an interposer substrate (intermediate circuit substrate), and the interposer substrate is mounted on a mother board (circuit substrate) by solder bumps or the like. Has become more and more.

[0004] Since the two boards, the motherboard and the interposer board, are sandwiched between the electronic component that is a heat source and the housing that is the heat radiation destination, the electronic components are mounted on a conventional motherboard. The heat radiation is lower than that of the structure in which the device is directly mounted.

[0005] As a technique for improving heat dissipation, the following structure has been conventionally known. In this structure, a metal core substrate in which a wiring layer and an insulating layer are formed on both sides of a metal plate as a core material is used for an interposer substrate. The resin layer on both sides of the interposer substrate and a part of the wiring layer are removed, and the semiconductor device as an electronic component is directly mounted on the upper surface of the core material in a face-up manner, and the lower surface of the core material and the upper surface of the motherboard are removed. The sides are connected by soldering and plating (Patent Document 1, FIG. 34).

Patent Document 1: Japanese Patent Application Laid-Open No. 2003-46022

Disclosure of the invention Problems the invention is trying to solve

[0007] However, in the above-described conventional technology, attention is paid to heat radiation between the interposer substrate mounted in the housing and the motherboard, but the heat radiation of the entire electronic device including the housing is improved. It is not fully considered.

[0008] That is, an object of the present invention is to improve the heat dissipation of an electronic device.

Means for solving the problem

[0009] The present application includes a plurality of inventions that can solve the above-mentioned problems, and representative ones will be described below.

[0010] A housing and an electronic board adhered to the housing are provided. The electronic board includes a first circuit board (interposer board) on which electronic components are mounted, and the first circuit board. And an electronic device having a second circuit board (mother board) electrically connected to the housing and fixed to the housing, wherein the interposer board is provided in a space not overlapping with the mother board. Fixed to. With such a structure, the area that can be used for fixing can be increased, and the following effects are obtained.

(1) By increasing the bonding area, even when a strong impact such as a drop is applied, disconnection between the interposer substrate and the motherboard can be suppressed.

(2) By using such a space as a heat radiation path, it is possible to form a large heat radiation path directly leading to the housing.

[0011] Further, it is preferable that the first circuit board of the above aspect is fixed to the housing via a member formed separately from the second circuit board.

[0012] There is a limit to the shape (area and thickness) that can be formed with a plating or the like, but if it is formed in advance as a separate part, the limit of the area and thickness does not need to be considered so much, and the cost is low. Large area can be fixed. Further, by using a member having a large heat conduction coefficient as a strong member, a heat radiation path having a large cross-sectional area can be secured.

[0013] In the above aspect, a through hole is formed in the second circuit board, and the second circuit board is provided in a space between the first circuit board and the housing and overlapping the through hole. It is preferable to provide a molded member separately from the circuit board of the second.

[0014] By providing the through-hole in the second substrate as described above, the first circuit board and the second circuit board are provided. Can be arranged at the center of the second circuit board. That is, since the heat radiating member can be arranged directly below the electronic component as the heat radiating source, the heat radiating property is improved.

[0015] Naturally, from the viewpoint of heat dissipation, it is preferable to use a member having a higher thermal conductivity than the second circuit board as the above-described member.

[0016] When high reliability is required, such as in an automobile, it is preferable to fill a space where the first substrate and the second substrate overlap with each other with a gel-like insulator.

[0017] It is preferable that at least one of the bonding surfaces of the member and the first circuit board and / or at least one of the bonding surfaces of the member and the housing have irregularities.

Further, when the member is a projection of the housing in which a part of the housing is molded, it is possible to prevent a decrease in thermal conductivity due to an adhesive layer used for connection, thereby contributing to an improvement in heat dissipation. I do.

In the case where a metal core substrate is used as the first circuit board, the metal plate is exposed at a part of the back surface and the part and the housing are bonded to each other, so that the heat radiation property is further improved. Can be improved.

This application is based on Japanese Patent Application No. 2003-170185 filed on June 16, 2003, the disclosure of which is incorporated by reference in its entirety. The invention's effect

According to the present invention, the heat dissipation of the electronic device can be improved.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-sectional view of an electronic device.

FIG. 2 is a perspective view of an ECU module.

FIG. 3 is a cross-sectional view illustrating a manufacturing process of the structure in FIG. 1.

FIG. 4 is a cross-sectional view of the electronic device.

FIG. 5 is a cross-sectional view of the electronic device.

FIG. 6 is a cross-sectional view of the electronic device.

FIG. 7 is a diagram showing a manufacturing process.

FIG. 8 is a cross-sectional view of the electronic device.

FIG. 9 is a cross-sectional view of the electronic device.

Explanation of reference numerals [0022] 1 ... semiconductor device, 3 ... bonding wire, 5 ... resin adhesive, 7 ... mold resin, 9 ... electronic parts, 11 ... interposer board, 13 ... circuit layer, 15 ... mother board, 17 ... circuit Layer, 19: Solder bump, 21: Electronic component, 23: Solder, 25: Silicone adhesive lj, 27: Aluminum housing, 29: Projection, 31: Resin adhesive, 33: Metal block, 35: Resin adhesive, 37: Metal core board, 39: Core metal (inner metal plate), 41: Semiconductor package, 43: Through hole, 45: Solder ball for heat dissipation

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 2 shows a perspective view of an engine control unit (ECU) module, which is an example of the electronic device, with a lid removed.

[0024] The ECU module is an aluminum housing on which a connector for inputting and outputting signals to and from the outside is formed.

27 (the lid of the housing 27 is not shown), a mother board (circuit board) 15 that is electrically connected to the connector and wiring, and is mounted on the aluminum housing 27, and on the mother board 15 A semiconductor package 41 is provided, and a silicone gel (not shown) filling the inside of the housing 27 is provided.

[0025] Note that the silicone gel may be omitted, but in this example, the silicone gel is filled from the viewpoint of improving reliability.

FIG. 1 is a cross-sectional view of FIG.

The semiconductor package 41 includes a circuit board (interposer board) 11 having a resin layer and a circuit layer 13, and is die-bonded to the interposer board 11 with an adhesive 5, and is electrically connected to the circuit layer 13 by bonding wires 3. Device 1, which is a power supply IC, which is electrically connected, and a resin 7, which molds the interposer substrate 11 so as to seal the semiconductor device 1, the bonding wires 3, and the circuit layer. . The adhesive 5 used for die bonding is a silver paste containing silver as a filler in a resin.

The mother board 15 is a circuit board including a resin layer and a circuit layer 17, on which electronic components 21 are mounted by solder 23, and a semiconductor package 41 is mounted by BGA (ball grid array) solder 19. ing.

Further, a through hole 43 is formed in a region of the mother board 15 that overlaps with a region on the interposer substrate 11 on which the semiconductor device 1 is mounted. The housing 27 has a projection 29, which is fitted in the through hole 43 of the motherboard 15, and the projection 29 and the interposer substrate 11 are fixed with an adhesive 31. In addition, portions other than the protrusion 29 are adhered to the motherboard 15 with an adhesive 25. As the adhesive 31, a resin adhesive (silver paste) 31 containing silicone containing a silver filler is used, and as the adhesive 25, a silicone adhesive (silver paste) is used.

As described above, by connecting the projections 29 of the housing 27 to the interposer substrate 11 by using the through holes 43 of the motherboard 15, the heat generated by the semiconductor device 1 causes the interposer substrate 11 to be confined. Heat can be dissipated to the case with high heat conductivity through a short heat dissipation path formed of a material with high heat conductivity. For this reason, the heat dissipation of the electronic device can be improved.

[0032] The resin adhesive 31 is made of a resin paste containing a filler having a higher thermal conductivity than resin, such as a metal other than silver or a metal inorganic compound such as alumina, or a thermal conductivity higher than the resin layer of the circuit board. It can be changed to solder with a large size.

[0033] In addition, the resin of the resin adhesive 31 can use a material other than silicone as long as the adhesive property can be secured. In this example, the difference in the thermal expansion coefficient between the interposer substrate and the mother board is used. In order to suppress the resulting thermal fatigue failure of the BGA solder joint, the destruction of the silver paste itself, and interface peeling, a silicone-based resin paste with a smaller Young's modulus than the solder material used for the BGA solder joint is used. The same effect can be obtained by using grease or sheet in addition to silicone resin.

Next, a manufacturing process of the ECU module of FIG. 1 will be described.

FIG. 3 is a diagram showing a manufacturing process of the ECU module of FIG.

First, a manufacturing process of the semiconductor package 41 will be described (FIG. 3 ()).

A 5 mm square semiconductor device 1 is placed face-up on the surface of the interposer substrate 11 and die-bonded with solder or silver paste 5. After die bonding, the terminals of the semiconductor device 1 and the pads of the interposer substrate 11 are electrically connected by the bonding wires 3. Next, the electronic components 9 are mounted. Note that this connection method is appropriately selected according to the type of electronic component.

Next, in order to enhance the handleability and reliability, the resin 7 is molded. Next, the package On the back surface of the substrate 11, pads for solder BGA connection are formed. Was formed by nickel plating and further gold plating with a diameter of 0.6 mm and a pitch of 1.27 mm. These pads were formed in a region B on the back surface of the position where the semiconductor device 1 was mounted, excluding a region A slightly larger than the size of the semiconductor device 1. At the same time as the formation of the nodes, a metal layer of about 5 mm square is formed in the area A excluding the nodes. The BGA connection pad was equipped with a 0.76 mm diameter Sn3Ag0.5Cu solder bonole 19 and reflowed to form solder bumps. A 5 mm square, 2. Omm high projection 29 was formed on the Anoremi housing 27 by rice milling.

Next, a manufacturing process of the motherboard 15 will be described.

[0040] A resin substrate (printed substrate, thickness: 1.5 mm) was prepared, and through holes 43 were formed at desired positions on the substrate by router processing, as shown in Fig. 3 (b).

Next, the joining between the motherboard 15 and the semiconductor package 41 will be described.

[0042] The semiconductor package 41 and the electronic component 21 are mounted in a predetermined position on the motherboard 15 in alignment with each other. At 240 ° C, the solder is melted for about 5 minutes, and reflow connection is performed (Fig. 3 ( c)). The size of the through hole was 7 mm square. Since the aluminum projection 29 is provided in the through hole 43 of the mother board 15, by making the opening larger than the size of the aluminum projection 29, the positioning accuracy of the board with respect to the housing 27 is improved. This is effective in alleviating the conditions described above and forming a space for storing an excess of the adhesive 31 for bonding the package 41 and the aluminum projection 29.

Next, a process of bonding the motherboard 15 on which the interposer substrate 11 is mounted to the aluminum housing 27 will be described.

[0044] A silicone adhesive 25 is applied to the substrate mounting portion of the aluminum housing 27 with the protrusions 29, and the protrusions 29 are mainly made of silicone having a high thermal conductivity and a small Young's modulus. Then, a silver paste 31 containing a silver filler is applied (FIG. 3D). A mother board (Fig. 3 (c)) with through-holes 43 with components mounted thereon is mounted on an aluminum housing 27, and the adhesive is cured at 150 ° C for 1 hour. From the hole 43 of the motherboard 15, the protruding portion 29 formed on the aluminum housing 27 protrudes from the surface of the substrate 15 by about 0.5 mm. The height of the solder ball that electrically connects the package 41 and the board 15 is about 0.4 mm, and the thickness of the board 15 is 1.6 mm, the thickness of the silicone adhesive 25 is about 0.1 mm, so the total thickness is about 2.1 mm. The thickness of the silver paste 31 may be about 0.1 mm.

It can be said that the structure of the above embodiment has the following features.

First, the electronic device includes a housing and an electronic substrate adhered to the housing. The electronic substrate is connected to an interposer substrate on which electronic components are mounted, and is electrically connected to the interposer substrate. And a first motherboard fixed to the housing. In this electronic device, the interposer substrate is fixed to the housing in a space that does not overlap with the motherboard.

[0047] Such a structure is not affected by the difference in the thermal expansion coefficient between the interposer substrate and the mother board, so that a stronger fixing can be obtained. By not interposing a mother board, there is no restriction on the fixing method, and the bonding area can be increased. Accordingly, even when a strong impact such as a drop is applied due to an increase in the bonding area, there is an effect that disconnection between the interposer substrate and the mother board can be suppressed. In addition, since heat can be dissipated without the intervention of a motherboard, a large heat dissipation path directly leading to the housing can be formed.

[0048] It is preferable that the interposer substrate is fixed to the housing via a member molded separately from the motherboard.

[0049] There is a limit to the shape (area and thickness) that can be formed by plating and the like, but if it is molded in advance as a separate part, it is not necessary to worry too much about the limit of the area and thickness, and low cost and large The area can be fixed. In addition, by using a member having a large heat conduction coefficient as a force member, a heat radiation path having a large cross-sectional area can be secured.

[0050] Further, a through hole is formed in the mother board, and a member formed separately from the mother board is provided in a space between the interposer substrate and the housing and overlapping with the through hole. It is preferable to provide

As described above, by providing the through holes in the mother board, a non-overlapping space between the interposer substrate and the mother board can be arranged at the center of the mother board. That is, since the heat radiating member can be arranged directly below the electronic component as the heat radiating source, the cross-sectional area of the path to the housing can be increased, and the heat radiating property is improved.

[0052] Naturally, from the viewpoint of heat dissipation, the above-described members are more thermally conductive than the resin layer of the motherboard. It is preferable to use one having a large conductivity.

In the in-vehicle electronic device, the space in which the interposer substrate and the mother board overlap is filled with a gel-like insulator, so that the above structure is particularly effective.

Further, since the member is a projection of the housing in which a part of the housing is formed, a decrease in thermal conductivity due to an adhesive layer used for connection can be prevented, thereby contributing to an improvement in heat dissipation.

Next, another structure different from FIG. 1 will be described.

FIG. 4 is a cross-sectional view of an ECU module different from FIG.

[0057] The inner surface side of aluminum casing 27 is almost flat. A separately molded aluminum metal block 33 is bonded to the aluminum housing 27 using a silicone adhesive 35 containing a metal filler.

According to the present embodiment, not only the fixing strength can be improved and the heat radiation property can be improved, but also the restriction on the positioning accuracy of the substrate with respect to the housing 27 can be eased. The adhesive 31 is preferably a resin paste containing a powder of silver or other metal having a high thermal conductivity or a metal inorganic compound such as alumina, or a solder having a higher thermal conductivity in terms of heat radiation characteristics.

[0059] Also, by using a silicone-based resin paste, grease, or sheet having a small Young's modulus as the adhesive 31, thermal fatigue destruction to the BGA solder connection part is reduced, and destruction of the silver paste itself and interface peeling are also performed. So that connection reliability can be reduced.

FIG. 5 is an embodiment different from the embodiment shown in FIG. 1 in the following points.

The substrate constituting the package is a metal core substrate 37. The insulating resin on the front and back of the metal core substrate 37 is partially removed, and the high-heat-generating chip 1 is bonded face-up with silver paste 5 to the exposed part of the core metal 39, and packaged with chip 1 by wire bonding 3 The bonding pads on the board (interposer board) are electrically connected. Other parts can also be mounted on the package substrate as needed and molded with resin 7 to improve handling. The protruding portion 33 of the aluminum housing 27 is adhered to the exposed portion of the core metal on the back surface of the package with a silicone-based silver paste 31. According to the present embodiment, since the connection from the high heat generating chip to the aluminum housing 27 having a large heat capacity can be connected without the insulating resin layer of the circuit board having low thermal conductivity, the heat radiation can be extremely enhanced. Also, By making at least one of the adhesive portions 31 and 35 an adhesive containing a non-conductive filler or an adhesive without a filler, it is also possible to maintain the insulation between the core metal 39 and the aluminum housing 27.

FIG. 6 is different from the above-described embodiment in that the connection between the core metal 39 and the aluminum protrusion 33 is performed by the solder ball 45. The manufacturing process can be simplified by connecting the heat radiating part with solder balls. Although the total connection area that contributes to heat dissipation is reduced, the thermal conductivity of the solder itself is about 10 times greater than that of silver paste, so it is possible to keep the heat dissipation lower than in the previous embodiment. If the entire silver paste connection portion in the above-mentioned embodiment is connected by solder instead of the solder ball, the heat dissipation can be further improved.

A manufacturing process for realizing the embodiment shown in FIG. 6 is briefly shown in FIG. 7, and will be described below.

First, a method of manufacturing the nocage part will be described (FIG. 7 (c) top). A metal core substrate 37 is used as a package substrate. The metal core substrate 37 is manufactured by a known method. However, it is necessary to remove the insulating resin portion of the metal core substrate 37, and this is performed by carbon dioxide laser processing. After the desmear treatment, a high heat-generating electronic component 1 of approximately 5 mm square is die-bonded to the surface of the core metal 39 face-up with solder or silver paste 5. Electrical connection is made by wire bonding 3. Mold with resin 7 to further improve handling and reliability. Pads for solder BGA connection are formed on the back of the package substrate. These pads have a diameter of 0.6 mm and a pitch of 127 mm, for example, and are formed by nickel plating and further gold plating. The BGA pad is not formed on the entire back surface of the substrate 37, and a part of a 5 mm square area for heat radiation is left. The above process is also effective for the embodiment shown in FIG. An insulating resin removing portion (borebore portion) 46 having a diameter of 0.6 mm and a pitch of 1.27 mm is formed in the heat radiation area. The counterbore portion 46 is formed by the same method as that of the chip mounting portion, that is, laser processing. Making the counterbore diameter about the same size as the other BGA pads allows the same solder ball size to be supplied, thus facilitating process control. Further, the heat radiation can be improved by reducing the pitch of the counterbore 46 to increase the number thereof or by increasing the area of the counterbore 46. Solder 0.76mm diameter Sn3Ag0.5Cu solder to BGA connection pad and heat sink Mount balls 19 and 45 and reflow to form solder.

As shown in FIG. 7 (b), a protrusion 33 having a 5 mm square and a height of 1.7 mm is formed at a desired position on the ECU aluminum housing 27. This projection 33 is formed by the method as in the above-described embodiment. As shown in Fig. 7 (c), on the protrusion 33, a metallization 38 for solder connection, that is, a nickel metal with a thickness of 5 microns, and even a 0.5 micron To form a gold plating. These metallizations 38 may be formed by any method as long as they react with the solder.

The board 15 is a resin board (printed board, thickness: 1.5 mm) by a known technique, and a hole 43 is formed at a desired position on the board 15 by a router process as shown in FIG. 7 (a). Keep it. The size of the hole 43 is 6 mm square. By making the size larger than the size of the aluminum protrusion 33, the restriction on the positioning accuracy of the substrate 15 with respect to the housing 27 can be relaxed.

In the present embodiment, a silicone adhesive 25 is applied to the substrate mounting portion of the aluminum housing 27 having the projections, and the perforated substrate 15 is mounted and cured at 150 ° C. for one hour. From the hole 43 of the substrate 15, the protruding portion 33 formed on the aluminum housing 27 protrudes from the surface of the substrate 15 by about 0.2 mm.

[0068] The package and other electronic components 21 are aligned and mounted at predetermined positions on the substrate 15, and the solder is melted at 240 ° C for about 5 minutes, and all solder joints are simultaneously reflow-connected. I do.

[0069] If the metal projections 33 for heat dissipation and the substrate opening are made larger than the size of the mounted chip in the above embodiment, the heat dissipation can be further improved. Further, if the metal projection 33 and the substrate opening 43 are smaller than the chip size, the area where the substrate 15 can be wired increases, and the size of the substrate 15 can be reduced. In addition, if the heat radiating section has a circular cross section that does not necessarily have to be a square or rectangular horizontal section, or if the corner has a rounded shape, molten solder or pre-curing plays an important role in alignment. The self-alignment function due to the surface tension of the resin can be more effectively exerted, and reliability can be improved by avoiding stress concentration.

FIG. 8 shows the structure of another electronic device.

The difference from the electronic device of FIG. 1 is that a minute groove or projection 100 is provided on the top surface of the projection 29. That is the point.

In the structure shown in FIG. 1, a minute gap is generated on the connection surface of the interposer substrate 11 due to the interposition of the adhesive 31 made of a resin adhesive or solder between the projection 29 and the interposer substrate 11. As shown in FIG. 8, by providing the minute projections 100, the gap can be reduced by pressing the projections 100 against the interposer substrate 11 while securing the adhesive force in the grooves, thereby improving heat dissipation. be able to.

FIG. 9 shows the structure of another electronic device.

A difference from the electronic device of FIG. 4 is that minute grooves or protrusions 101 and 102 are provided on the upper surface and the lower surface of the metal block 33 ′.

In the structure shown in FIG. 4, adhesives 31 and 35 made of a resin adhesive or solder are interposed between metal block 33 and housing 27 and between metal block 33 and interposer substrate 11. By doing so, a minute gap is created at the connection surface. However, as shown in FIG. 9, the protrusions 101 and 102 are pressed against the interposer substrate 11 while securing the adhesive force by the grooves by providing the minute protrusions 101 and 102 on the upper surface and the lower surface of the metal block 33 ′. By doing so, these intervals can be reduced, so that heat dissipation can be improved.

When the metal block 33 ′ having irregularities formed by the projections and the grooves is applied to the metal block 33 shown in FIGS. However, the upper surface of the metal block 33 having the structure shown in FIG. 6 is connected to solder bumps, and it is preferable that there is no unevenness.

The groove or the protrusion for securing the adhesive force is at least one of the protrusion 29 and the bonding surface of the interposer substrate 11, at least one of the metal block 33 ′ and the bonding surface of the interposer substrate 11, and the metal block 33 ′. And at least one of the bonding surfaces of the housing 27.

Industrial applicability

[0078] The present invention is applicable to an electronic device that requires a high heat radiation structure typified by an engine control unit.

Claims

The scope of the claims

[1] a housing, and an electronic board adhered to the housing,

The electronic substrate is

A first circuit board on which the electronic component is mounted,

An electronic device having a second circuit board electrically connected to the first circuit board and fixed to the housing,

The electronic device, wherein the first circuit board is fixed to the housing in a space that does not overlap with the second circuit board.

[2] The electronic device according to claim 1,

The electronic device, wherein the first circuit board is fixed to the housing via a member formed separately from the second circuit board.

[3] The electronic device according to claim 1 or 2,

A through-hole is formed in the second circuit board,

The electronic device is

An electronic device comprising a member formed separately from the second circuit board in a space between the first circuit board and the housing and overlapping the through hole.

[4] The electronic device according to any one of claims 1 to 3,

The electronic device, wherein the member has a higher thermal conductivity than the second circuit board.

[5] The electronic device according to any one of claims 1 to 4, wherein

An electronic device, wherein a space in which the first substrate and the second substrate overlap with each other is filled with a gel-like insulator.

[6] The electronic device according to any one of claims 2 to 5, wherein

A structure in which the member and the housing are bonded to each other with a solder or a resin adhesive containing a resin having a higher thermal conductivity than the resin, and

A structure in which the member and the first circuit board are bonded to each other with a solder or a resin adhesive containing a filler having a higher thermal conductivity than the resin;

An electronic device having at least one of the above structures.

[7] The electronic device according to any one of claims 2 to 6,

An electronic device, wherein at least one of an adhesive surface of the member and the first circuit board or at least one of an adhesive surface of the member and the housing has irregularities.

[8] The electronic device according to any one of claims 2 to 5, wherein

The electronic device according to claim 1, wherein the member is a protrusion of the housing in which a part of the housing is formed.

[9] In claim 8,

An electronic device, wherein the member and the first circuit board are bonded by solder or an adhesive containing a resin and a filler having a higher thermal conductivity than the resin.

[10] The electronic device according to claim 8 or 9,

An electronic device, characterized in that at least one of the bonding surfaces of the member and the first circuit board has irregularities.

[11] The electronic device according to claim 2,

The first circuit board is a metal core board in which a resin layer and a circuit layer are formed on both sides of a metal plate, and the metal plate is exposed on a part of the back surface, and the exposed portion is provided. An electronic device, wherein the housing and the housing are connected via the member.

[12] The electronic device according to claim 11,

An electronic device, wherein the metal plate has irregularities on a connection surface with the member.

[13] The electronic device according to claim 3,

An electronic device, wherein there is a gap between the member and a side wall of the through hole.

[14] The electronic device according to claim 2,

The bonding strength between the member and the first circuit board is smaller than the Young's modulus of the solder used for connecting the circuit on the front side of the second circuit board and the circuit on the back side of the first circuit board. An electronic device, wherein the adhesive has a smaller Young's modulus.

[15] The electronic device according to claim 11,

The first circuit board has a region on the surface where the metal plate is exposed, the electronic component is die-bonded on the metal plate in that region, and the first component is bonded by wire bonding. A first circuit board circuit layer and a terminal of the electronic component are joined to each other;

[16] The electronic device according to claim 2,

An electronic device, wherein a space between the member and the first circuit board is fixed with an adhesive containing a filler in silicone.

[17] The electronic device according to claim 2,

An electronic device, wherein the second circuit board and the first circuit board are connected by a lead-free solder containing Sn and Ag.

[18] a housing, and an electronic board adhered to the housing,

The electronic substrate is

A first circuit board on which electronic components are mounted;

An electronic device, wherein the first circuit board is fixed to the housing without interposing the second circuit board.