JP2016076622A - Circuit board and electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit board which enables a heat conduction member to be assembled to a through hole of the circuit board without increasing the manufacturing costs, and to provide an electronic device.SOLUTION: In a circuit board 20, a male screw part 32 is formed on an outer peripheral surface of a heat conduction member 30 for radiating heat of a heating component 40. The heat conduction member 30 is screwed into a through hole 22 to be assembled to the circuit board 20.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a circuit board and an electronic device provided with a heat conduction member that promotes heat dissipation of a heat-generating component.

  As a circuit board for controlling a motor, an alternator, an actuator and the like, a circuit board in which electronic parts are mounted on a resin printed board using solder or the like is generally used. In recent years, electromechanical integrated products in which an electronic control circuit structure such as the circuit board is directly mounted on a mechanical structure such as a motor are increasing due to demands for reduction in size, weight, and performance of the entire product. As described above, by integrating the mechanical structure such as a motor and the electronic control circuit structure, which is conventionally separate, the thermal environment in the electronic control circuit structure may be deteriorated.

  In order to improve the deterioration of the thermal environment, it is necessary to improve the heat dissipation performance of the heat generating components. As a technique related to a circuit board with improved heat dissipation of a heat-generating component, a heat conduction structure of a printed circuit board disclosed in Patent Document 1 below is known. In the heat conduction structure of this printed circuit board, a through hole is formed in an insulating substrate material having a conductor layer bonded on both sides, and the diameter is expanded and pressed against the through hole with the heat conduction member inserted. Then, after the substrate surface is polished and a required circuit pattern is formed by plating, etching, or the like, the heat generating component is mounted. Thereby, the heat dissipation of the heat generating component is promoted through the heat conducting member.

JP 2010-263003 A

  By the way, in the above-described configuration, unnecessary steps are required in a normal substrate manufacturing process, such as diameter expansion deformation of the heat conducting member and polishing of the substrate surface. If it does so, the problem that manufacturing cost will increase arises.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a circuit board and an electronic device capable of assembling a heat conducting member into a through hole of a circuit board without increasing manufacturing costs. It is to provide.

  In order to achieve the above object, the invention according to claim 1 of the present invention is characterized in that the heat conducting member (30, 30a to 30e) for heat dissipation is formed in the through hole (22, 22a) with respect to the heat generating component (40). The heat conductive member has a male screw part (32, 32a) formed on the outer peripheral surface thereof, and is assembled by being screwed into the through hole.

An electronic device (10) according to claim 7 comprises the circuit board according to any one of claims 1 to 6.
In addition, the code | symbol in the parenthesis of a claim and the said means shows a corresponding relationship with the specific means as described in embodiment mentioned later.

  According to the first aspect of the present invention, the external thread portion is formed on the outer peripheral surface of the heat conducting member for heat dissipation with respect to the heat generating component, and the heat conducting member is assembled by being screwed into the through hole. Thereby, the heat conduction member can be easily assembled in the through hole of the circuit board without requiring the diameter expansion deformation of the heat conduction member or the polishing process of the substrate surface, that is, without increasing the manufacturing cost.

  In the invention of claim 7, since the electronic device is configured to include the circuit board as described above, there is an effect that the heat conducting member can be assembled into the through hole of the circuit board without increasing the manufacturing cost. An electronic device can be realized.

It is sectional drawing which shows schematic structure of the circuit board and electronic device which concern on 1st Embodiment. It is sectional drawing for demonstrating the assembly | attachment process of the heat conductive member in 1st Embodiment. It is sectional drawing which shows schematic structure of the circuit board which concerns on the modification of 1st Embodiment. It is sectional drawing which shows schematic structure of the circuit board and electronic device which concern on 2nd Embodiment. It is sectional drawing for demonstrating the assembly | attachment process of the heat conductive member in 2nd Embodiment. It is sectional drawing which shows schematic structure of the circuit board and electronic device which concern on 3rd Embodiment. It is sectional drawing which shows schematic structure of the circuit board which concerns on the modification of 3rd Embodiment. It is sectional drawing which shows schematic structure of the circuit board and electronic device which concern on 4th Embodiment. It is sectional drawing which shows schematic structure of the circuit board and electronic device which concern on 5th Embodiment.

[First Embodiment]
A first embodiment that embodies a circuit board and an electronic device according to the present invention will be described below with reference to the drawings.
The electronic device 10 shown in FIG. 1 is mounted on a circuit board with a heat-generating component that generates heat in accordance with its control, such as an electronic control unit (Electronic Control Unit) that controls in-vehicle equipment such as an engine mounted on a vehicle. It is configured as a device. The electronic device 10 includes a metal (for example, aluminum) casing 11 that forms an outer shell, a circuit board 20 that is accommodated in the casing 11, and the like. In FIG. 1, for convenience, a part of the housing 11 and the circuit board 20 are illustrated in cross section.

  The circuit board 20 is an electronic component (hereinafter referred to as a power MOSFET, for example) that generates heat on a mounting surface 21a of a multilayer circuit wiring board in which insulating layers and conductive layers made of epoxy resin or the like are alternately stacked. , Also referred to as a heat generating component 40), a connector, and the like are mounted through a reflow process or the like. The circuit board 20 is accommodated in the casing 11 while being supported at a predetermined position using a pedestal 13 or the like provided on the bottom surface 12 of the casing 11.

  On the circuit wiring board of the circuit board 20, a heat conducting member 30 for promoting heat dissipation of the heat generating component 40 is assembled. The heat conducting member 30 is a substantially cylindrical inlay configured using a material having high heat conductivity such as copper, and has an external thread portion 32 formed on the outer peripheral surface. The heat conducting member 30 is located immediately below the terminal 41 of the heat generating component 40, and is formed from the surface opposite to the mounting surface 21a of the circuit board 20 (hereinafter also simply referred to as the back surface 21b) to the mounting surface 21a. By being screwed into the through hole 22, it is assembled so as to be embedded.

  In the present embodiment, the male screw portion 32 is formed so that the effective diameter is substantially constant from the heat generating component side 31a to the counter heat generating component side 31b. The heat conducting member 30 is screwed so that the heat-generating component side 31a and the surface of the land 23 of the mounting surface 21a are substantially flush and the counter-heat-generating component side 31b and the back surface 21b are substantially flush. (See FIG. 1). Note that an engagement groove (not shown) for screwing such as a cross groove is formed on the side 31b of the heat conducting member 30 opposite to the heat generating component.

  The heat conducting member 30 configured as described above is thermally connected to the terminal 41 of the heat generating component 40 via the solder 24 on the heat generating component side 31a while being embedded in the circuit board 20. Thereby, the heat conductive member 30 functions to promote the heat from the heat generating component 40 to the back surface 21b side. In addition, the terminal 41 is formed so that the surface area may become large in order to improve heat dissipation.

  Next, the assembly process of the heat conductive member 30 will be described in detail with reference to FIG. 2 is a cross-sectional view for explaining the assembly process of the heat conducting member 30. FIG. 2A shows a state in which the through hole 22 is formed, and FIG. The state in which the heat conductive member 30 is screwed is shown.

  First, the base material 20a for forming the circuit board 20 and the heat conducting member 30 formed as described above are prepared. Then, as shown in FIG. 2 (A), the base 20a having the land 23 and the like formed at a predetermined position on the mounting surface 21a by plating or the like is cross-sectionalized at the above-described position using drilling. A circular through hole 22 is formed. In the present embodiment, the through hole 22 has a substantially constant inner diameter from the mounting surface 21 a to the back surface 21 b and is formed so that the inner diameter is slightly smaller than the effective diameter of the male screw portion 32.

  Then, as shown in FIG. 2B, the heat conduction member 30 prepared in advance is screwed into the through hole 22 of the base material 20a from the back surface 21b side. Specifically, while the heat conducting member 30 is rotated using a screwing engagement groove formed on the counter heat generating component side 31b, the heat generating component side 31a is substantially flush with the surface of the land 23. Screw in. At this time, since the through hole 22 is formed so that the inner diameter thereof is smaller than the effective diameter of the male screw portion 32, the heat conducting member 30 is screwed so as to cut the inner peripheral surface of the through hole 22. It becomes.

  As described above, using the circuit wiring board in which the heat conducting member 30 is embedded in the base material 20a, the solder paste is printed at a predetermined position, and then the heat generating component 40 and the like are mounted to perform the reflow process. Thus, the circuit board 20 is completed such that the heat conducting member 30 is thermally connected to the terminals 41 of the heat generating component 40 via the solder 24 on the heat generating component side 31a (see FIG. 1).

  As described above, in the circuit board 20 according to the present embodiment, the external thread portion 32 is formed on the outer peripheral surface of the heat conducting member 30 for heat dissipation with respect to the heat generating component 40, and the heat conducting member 30 is formed in the through hole 22. It is assembled by being screwed into. Thus, the heat conducting member 30 can be easily assembled in the through hole 22 of the circuit board 20 without requiring the diameter expansion deformation of the heat conducting member 30 or the polishing of the substrate surface, that is, without increasing the manufacturing cost. Can do.

  Since the electronic device 10 according to the present embodiment is configured to include the circuit board 20 as described above, the heat conducting member 30 is assembled to the through hole 22 of the circuit board 20 without increasing the manufacturing cost. It is possible to realize an electronic device that exhibits the operational effect of being able to.

  Further, since the heat conducting member 30 is screwed into the through hole 22 so as to be positioned directly below the heat generating component 40, the heat of the heat generating component 40 is easily transmitted to the heat conducting member 30, and the heat dissipation effect by the heat conducting member 30 is achieved. Can be increased. Even when at least a part of the heat conducting member 30 is located directly below the heat generating component 40, the heat of the heat generating component 40 is transmitted to the heat conducting member 30.

  In particular, the male screw portion 32 of the heat conducting member 30 is formed so that the effective diameter is constant from the heat generating component side 31 a to the counter heat generating component side 31 b, so that the male screw portion 32 can be easily formed on the outer peripheral surface of the heat conducting member 30. Can be formed.

FIG. 3 is a cross-sectional view illustrating a schematic configuration of a circuit board according to a modification of the first embodiment.
The heat conducting member 30 is not limited to being screwed into the through hole 22 so that the heat generating component side 31a and the surface of the land 23 of the mounting surface 21a are substantially flush. For example, the heat generating component side 31a and the mounting surface 21a May be screwed into the through hole 22 so as to be substantially flush. In this case, as illustrated in FIG. 3, since the plating film constituting the land 23 is interposed between the heat conducting member 30 and the solder 24, the screwing position of the heat conducting member 30 is slightly deviated from the mounting surface 21a. Even if it is, the heat conducting member 30 and the solder 24 are surely thermally connected. Thereby, the assembly | attachment precision required regarding the screwing position of the heat conductive member 30 can be reduced. The same effect is achieved in other embodiments described later.

[Second Embodiment]
Next, a circuit board and an electronic device according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a cross-sectional view illustrating a schematic configuration of the circuit board 20 and the electronic device 10 according to the second embodiment. FIG. 5 is a cross-sectional view for explaining the assembly process of the heat conducting member 30a in the second embodiment. FIG. 5 (A) shows a state in which the through hole 22a is formed, and FIG. A state where the heat conducting member 30a is screwed into the hole 22a is shown.
The second embodiment is mainly different from the first embodiment in that a heat conducting member 30a is employed instead of the heat conducting member 30 described above. For this reason, substantially the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 4, the heat conducting member 30 a according to the present embodiment is formed such that its effective diameter gradually increases from the heat generating component side 31 a to the counter heat generating component side 31 b. Specifically, the male threaded portion 32a is formed in a truncated cone shape so that the effective diameter spread angle θ is approximately 45 °, for example.

  Since the effective diameter gradually increases from the heat-generating component side 31a to the counter-heat-generating component side 31b, heat transmitted from the heat-generating component side 31a is easily diffused, so that the heat dissipation effect by the heat conducting member 30a can be enhanced. In general, the heat spreads more easily as the spread angle θ is increased, while the diffusion effect does not change even if the spread angle θ exceeds 45 °. Therefore, in this embodiment, by setting the spread angle θ of the effective diameter of the male screw portion 32a to 45 °, the heat radiation effect by the heat conducting member 30a is maximized, and the region occupied by the heat conducting member 30a is reduced. Thus, the circuit board 20 can be reduced in size and weight.

  As shown in FIG. 5 (A), the heat conductive member 30a formed as described above has the through hole 22a formed in the base material 20a, and then the heat conductive member 30a is formed as shown in FIG. 5 (B). By screwing from the back surface 21b side into the through hole 22a of the base material 20a, it is embedded in the base material 20a. The through hole 22a is formed so that its inner diameter gradually increases from the mounting surface 21a to the rear surface 21b and slightly smaller than the effective diameter of the male screw portion 32a.

[Third Embodiment]
Next, a circuit board and an electronic device according to a third embodiment of the present invention will be described with reference to FIG. FIG. 6 is a cross-sectional view illustrating a schematic configuration of the circuit board 20 and the electronic device 10 according to the third embodiment.
The third embodiment is mainly different from the second embodiment in that a heat conducting member 30b is employed instead of the above-described heat conducting member 30a. For this reason, substantially the same components as those in the second embodiment are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 6, the heat conducting member 30 b according to the present embodiment is formed such that the counter-heat-generating component side 31 b protrudes as the protruding portion 33 from the back surface 21 b. As a result, the volume of the heat conducting member 30b is increased by the amount of the protruding portion 33 as compared with the heat conducting member 30a, so that the heat radiation effect by the heat conducting member 30b can be enhanced as compared with the heat conducting member 30a. In the present embodiment, the protruding portion 33 is formed so that the outer diameter is constant toward the counter-heat-generating component side 31b.

FIG. 7 is a cross-sectional view illustrating a schematic configuration of a circuit board according to a modification of the third embodiment.
The heat conducting member may be formed such that the protruding portion protruding from the back surface 21b has a larger diameter. Specifically, for example, as the protrusion 33a of the heat conducting member 30c illustrated in FIG. 7 is formed so as to expand the diameter at a spread angle θ of 45 °, the heat using the protrusion 33a. The circuit board 20 can be miniaturized by maximizing the heat dissipation effect by the conductive member 30c and reducing the area occupied by the heat conductive member 30c. In addition, the external thread part does not need to be formed in the outer peripheral surface of the protrusion part 33a.

  In addition, also in the heat conductive member 30 described in the said 1st Embodiment, the thermal radiation effect can be heightened by providing the protrusion parts 33 and 33a as mentioned above.

[Fourth Embodiment]
Next, a circuit board and an electronic device according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 8 is a cross-sectional view illustrating a schematic configuration of the circuit board 20 and the electronic device 10 according to the fourth embodiment.
The fourth embodiment is mainly different from the third embodiment in that the circuit board is supported on the housing using a heat conducting member. For this reason, substantially the same components as those in the third embodiment are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 8, the heat conducting member 30 d according to the present embodiment has a female screw portion 35 formed on the end surface (hereinafter also referred to as the projecting end surface 34) of the projecting portion 33 on the side opposite to the heat generating component (housing side) 31 b. Yes. Further, in the housing 11a according to the present embodiment, the through hole 14 is formed in the bottom surface 12 where the female screw portion 35 of the heat conducting member 30d faces when the circuit board 20 is accommodated.

  And after the thermal radiation gel 16 is apply | coated as a flexible member which has thermal conductivity between the protrusion end surface 34 and the bottom face 12 around the through-hole 14, the screw 15 which penetrates the through-hole 14 is fastened to the internal thread part 35. As a result, the heat conducting member 30d is fixed to the housing 11a.

  Thereby, since the heat transmitted to the heat conducting member 30d is easily radiated to the housing 11a via the protruding end surface 34, the heat radiation effect by the heat conducting member 30d can be enhanced. In particular, since the non-mounting region due to the fastening is not formed by fastening using the heat conducting member 30d, the mounting is compared with the case where the non-mounting region is formed by simply screwing to the board surface. The density increases and the circuit board 20 can be downsized.

  Further, in the present embodiment, the heat radiating gel 16 is applied between the protruding end surface 34 and the bottom surface 12 around the through hole 14. As a result, the projecting end surface 34 and the bottom surface 12 come into close contact with each other via the heat radiating gel 16 in accordance with the fastening force when the screw 15 is fastened to the female screw portion 35, so that heat dissipation to the housing 11a can be further promoted. it can. In addition, it replaces with the thermal radiation gel 16, and there exists the said effect, even if it arrange | positions the flexible member which has other thermal conductivity, such as a thermal radiation adhesive, between the projecting end surface 34 and the bottom face 12 around the through-hole 14. FIG.

  The protruding portion of the heat conducting member 30d may be formed so as to increase in diameter toward the counter-heat-generating component side 31b in order to enhance the heat dissipation effect, and the heat dissipation effect can be maximized like the above-described protrusion 33a. For the purpose of illustration, it may be formed so that the diameter is expanded when the spread angle θ is 45 °.

[Fifth Embodiment]
Next, a circuit board and an electronic device according to a fifth embodiment of the present invention will be described with reference to FIG. FIG. 9 is a cross-sectional view illustrating a schematic configuration of the circuit board 20 and the electronic device 10 according to the fifth embodiment.
The fifth embodiment is mainly different from the fourth embodiment in that the waterproof property is improved with respect to the configuration in which the circuit board is supported on the housing using the heat conducting member. For this reason, the same reference numerals are given to substantially the same components as those in the fourth embodiment, and the description thereof will be omitted.

  As shown in FIG. 9, the heat conductive member 30e according to the present embodiment has an annular protrusion (hereinafter also referred to as an annular protrusion 36) on the protruding end surface 34 of the protrusion 33 with respect to the heat conductive member 30d. It is formed to be newly prepared. The annular protrusion 36 is formed in an annular shape so as to surround the female screw portion 35. Further, an annular groove portion (hereinafter also referred to as an annular groove portion 17) into which the annular protrusion 36 is inserted is formed on the bottom surface 12 of the housing 11 a so as to surround the through hole 14. In addition, in order to improve the sealing performance by the heat conducting member 30e, it is desirable to arrange the annular groove portion 17 near the through hole 14.

  Then, after applying a predetermined amount of heat-conductive sealing material 18 in the annular groove 17, the heat conductive member 30 e is assembled to the housing 11 a so as to insert the annular protrusion 36 into the annular groove 17, and penetrates The screw 15 that passes through the hole 14 is fastened to the female screw portion 35. Thereby, the heat conductive member 30e is fixed to the housing 11a in a state in which the sealing material 18 is filled between the annular protrusions 36 in the annular groove 17 (see FIG. 9).

  In this manner, since the screw 15 is fastened to the female screw portion 35 in a state where the seal material 18 is filled between the annular protrusion 36 and the annular protrusion 36 in the annular groove portion 17, this fastening force causes the seal material 18 to be connected to the annular protrusion portion. 36 and the annular groove portion 17 can be reliably interposed. Thereby, the heat dissipation to the housing | casing 11a via the sealing material 18 can further be accelerated | stimulated, ensuring the sealing performance in the outer peripheral side from the annular groove part 17. FIG.

  The annular protrusion 36 and the annular groove 17 are not limited to being formed in an annular shape, and may be formed in a rectangular shape so as to surround the female screw portion 35 and the through hole 14, for example.

  Further, the protruding portion of the heat conducting member 30e may be formed so as to increase in diameter toward the counter-heat-generating component side 31b in order to enhance the heat dissipation effect, and the heat dissipation effect can be maximized like the protrusion 33a described above. For the purpose of illustration, it may be formed so that the diameter is expanded when the spread angle θ is 45 °.

[Other Embodiments]
In addition, this invention is not limited to said each embodiment, For example, you may actualize as follows.
(1) The heat conductive members 30 and 30a to 30e are not limited to being configured as copper inlays, but include, for example, members made of other highly heat conductive materials such as aluminum members and ceramic members. May be.

(2) The circuit board 20 configured as described above is not limited to being housed in a housing that requires sealing performance, but is housed in a housing that requires low sealing performance or a housing that does not require sealing performance. May be.

(3) The housing 11 is not limited to being formed of a metal such as aluminum, that is, a member made of a material having high thermal conductivity, and the circuit board 20 is simply replaced with the base 13 or the like as in the first embodiment. If it is the structure supported using, it may be formed by the member which consists of material with comparatively low heat conductivity like a resin material.

DESCRIPTION OF SYMBOLS 10 ... Electronic device 11, 11a ... Housing 20 ... Circuit board 22, 22a ... Through-hole 30, 30a-30e ... Heat conduction member 32, 32a ... Male screw part 33, 33a ... Projection part 35 ... Female screw part 40 ... Heat-generating component

Claims (11)

A heat conductive member (30, 30a to 30e) for heat dissipation with respect to the heat generating component (40) is a circuit board (20) assembled in the through hole (22, 22a)
The heat conductive member has a male screw part (32, 32a) formed on an outer peripheral surface thereof, and is assembled by being screwed into the through hole.   The circuit board according to claim 1, wherein the heat conducting member is screwed into the through hole so that at least a part of the heat conducting member is located immediately below the heat generating component.   The circuit board according to claim 1 or 2, wherein the male screw portion (32) is formed to have a constant effective diameter from the heat generating component side (31a) to the counter heat generating component side (31b).   3. The circuit board according to claim 1, wherein the male screw portion (32 a) is formed so that an effective diameter gradually increases from a heat generating component side (31 a) to a counter heat generating component side (31 b). .   The circuit board according to claim 1, wherein the heat conducting member protrudes from a surface (21 b) opposite to the mounting surface (21 a) on which the heat generating component is mounted. .   The circuit board according to claim 5, wherein the heat conducting member has a projecting portion (33 a) projecting from the opposite surface having a larger diameter.   An electronic device (10) comprising the circuit board according to any one of claims 1-6. A housing (11, 11a) in which the circuit board is accommodated,
The electronic device according to claim 7, wherein the heat conducting member is fixed to the housing. A female screw part (35) is formed on the end surface (34) on the housing side of the heat conducting member,
The electronic device according to claim 8, wherein the heat conducting member is fixed to the housing by being fastened using the female screw portion.   The electronic device according to claim 8 or 9, wherein a flexible member (16) having thermal conductivity is disposed between the heat conducting member and the housing. An annular protrusion (36) is formed on the end surface of the heat conducting member on the housing side,
The casing is formed with an annular groove (17) into which the protrusion is inserted,
The electronic device according to any one of claims 8 to 10, wherein the groove portion is filled with a sealing material (18) having thermal conductivity.

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