JP2003031978A - Control unit and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance cooling efficiency of a circuit substrate in a control unit and enable easy manufacture of the unit. SOLUTION: The unit comprises a circuit substrate 10, whereon a semiconductor device 12 is mounted and a heat dissipating member 20 for the cooling. A substrate-holding part 24, having a substrate holding groove 24a, is formed integrally in a rear of the heat-dissipating member 20. Both end parts of the circuit substrate 10 are inserted to the substrate-holding groove 24a. Thereby, the substrate 10 can be held at the heat dissipation member 20 side, so as to keep the substrate 10 held almost parallel with a rear of the heat dissipation member 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control unit equipped with a circuit board on which a semiconductor device is mounted and mounted in an automobile or the like, and a technique for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, semiconductor devices such as FETs have been widely used as devices mounted on a circuit board of a control unit. While such a semiconductor device is small and has excellent functions, it generates a relatively large amount of heat.
The heat dissipation becomes an important issue.

Conventionally, as a control unit using such a semiconductor device, for example, JP-A-11-21
In Japanese Patent No. 4875, a plurality of semiconductor devices (IP in the same publication) are mounted on a common mounting block protruding from the inner surface of the housing.
While fixing S), a screw for fastening a metal bracket to the housing is screwed into the inside of the mounting block, and heat generated by each semiconductor device is used as a medium through the mounting block and the screw. It is disclosed that it is transmitted to a bracket.

[0004]

In the structure disclosed in the above publication, since the mounting block of the housing is interposed between each semiconductor device and the screw and the thickness thereof is relatively large, high heat dissipation is achieved. It is difficult to expect the performance (that is, the cooling performance of the semiconductor device). Moreover, only the semiconductor device can be cooled, and the entire circuit board cannot be cooled effectively.

Further, the work of fixing each semiconductor device to the mounting block with screws is troublesome, and such inconvenience becomes more remarkable as the number of semiconductor devices increases.

Furthermore, the structure is such that the terminal legs of each semiconductor device fixed to the mounting block face the corners of the bottom surface of the housing, and the terminal legs of each semiconductor device are connected to the circuit board. Since the semiconductor device is assembled in a procedure of fixing the semiconductor device to the mounting block after mounting it on the mounting block, the assembling work is troublesome and a large stress is generated in the soldering portion between each terminal leg and the circuit board. There is a risk.

That is, since a dimensional error is always generated in manufacturing both the mounting block and each semiconductor device, the relative position between the mounting block and each semiconductor device is deviated by an amount corresponding to the dimensional error. Nevertheless, by fixing the semiconductor device to the mounting block, the terminal leg of the semiconductor device is deformed, and stress is generated in the soldering part connecting the terminal leg and the circuit board. As a result, a crack may occur between the solder and the terminal leg portion or the circuit board to cause an electrical failure.

In view of such circumstances, the present invention provides a control unit which is excellent in heat dissipation, has a simple assembly structure, and does not adversely affect the mounting state of semiconductor devices on a circuit board. An object of the present invention is to provide a method capable of easily manufacturing the unit.

[0009]

As a means for solving the above-mentioned problems, the present invention is provided with a circuit board on which a semiconductor device is mounted and a surface opposite to the mounting surface so as to face each other. A heat dissipating member, wherein the heat dissipating member has a substrate holding groove into which both ends of the circuit board are inserted;
The control unit is characterized in that, in the inserted state, the circuit board is held on the heat dissipation member side in a state of being close to the back surface of the heat dissipation member and being substantially parallel to the back surface.

Further, the present invention is a method of manufacturing a control unit including a circuit board on which a semiconductor device is mounted, and a heat radiating member arranged so as to face a surface opposite to the mounting surface thereof. A heat dissipation member forming step of integrally forming a heat dissipation member having a board holding groove on the back surface side into which both ends of the circuit board are inserted, and inserting the both ends of the circuit board into the board holding groove of the heat dissipation member Is held on the side of the heat dissipation member so as to be close to the back surface and substantially parallel to the back surface.

According to these configurations, the relative positioning of the two can be reliably performed only by inserting the circuit board into the board holding groove formed integrally with the heat dissipation member.
At the relative position, high heat dissipation performance (cooling performance of the circuit board) can be obtained by bringing the circuit board and the back surface of the heat dissipation member in close proximity to each other. Further, it does not adversely affect the mounting state of the semiconductor device on the circuit board.

The circuit board may be an ordinary insulating board made of synthetic resin or the like, but is made of a metal (more preferably made of a metal having excellent thermal conductivity such as aluminum or aluminum alloy). If the wiring material is provided on the surface of the substrate body via an adhesive layer having an insulating property and the semiconductor device is mounted on the wiring material, the semiconductor device emits The heat can be satisfactorily transferred to the heat dissipation member through the metal substrate body.

As a concrete structure of the heat dissipation member, a pair of substrate holding portions for sandwiching the circuit board from both sides are formed on the back surface of the heat dissipation member, and the substrate holding groove is formed on the inner side surfaces of these substrate holding portions. Those that are suitable are preferred. According to this structure, the circuit board can be compactly accommodated in the space formed between the board holding portions.

Regarding the positional relationship between the circuit board and the heat radiating member, a gap is secured between the circuit board held by the substrate holding groove and the back surface of the heat radiating member, and an insulating paste having thermal conductivity is provided in this gap. The intervening configuration is
More preferable. Furthermore, by using the insulating paste as an adhesive, it is possible to achieve integration of the circuit board and the heat dissipation member and electrical insulation between the two with a simple structure.

It is preferable to form a fin for increasing the surface area on the outer surface of the heat radiating member. However, by forming the fin in parallel with the substrate holding groove, an extruded product is formed on the heat radiating member. Can be used, which greatly enhances the mass productivity of the heat dissipation member.

Further, the heat dissipation member has a structure in which an escape groove, which is parallel to the board holding groove and is provided to escape the head of the screw protruding to the back surface of the circuit board, is formed on the back surface of the heat dissipation member. It is possible to avoid interference between the back surface of the heat dissipation member and the screw head while using the heat dissipation member as an extrusion molded product.

In the control unit provided with the heat dissipation member made of such an extruded product, in the heat dissipation member forming step, a step of extruding a molded body having the substrate holding groove and a fin parallel to the substrate holding groove on the outer surface is extruded. And a step of cutting the molded body into an appropriate size can be carried out, and high productivity can be obtained by adopting such a method.

In order to effectively protect the circuit board in the control unit, a cover may be provided to cover the board from the side opposite to the heat dissipation member. In this case, if a locking portion that locks the cover is formed on the peripheral edge of the heat dissipation member and the cover is directly locked to the heat dissipation member side, the cover has a simple structure. Can be installed and the circuit board can be reliably protected.

Further, if a through hole is provided in the cover in advance, it is possible to impart high waterproofness by a simple process of injecting the potting material through the through hole.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION A preferred embodiment of the present invention will be described with reference to FIGS.

The control unit shown in FIGS. 1 to 4 includes a circuit board 10, a heat dissipation member 20, and a cover 30.

The circuit board 10 incorporates a control circuit, and as shown in FIG. 2, a wiring pattern (wiring material) 16 is arranged on both front and back surfaces of the substrate body 11 via an adhesive layer 15 having an insulating property. It has an established structure. The substrate body 11 is made of a metal having excellent thermal conductivity such as aluminum or aluminum alloy. Also, the adhesive layer 1
For 5, it is preferable to use an adhesive having excellent thermal conductivity.

On the front wiring pattern 16 of the circuit board 10, a large number of circuit elements including a semiconductor device 12 such as an FET and a board connector 14 are mounted. The board connector 14 is fixed to the circuit board 10 by a screw 18 inserted through the through hole of the circuit board 10 from the back side of the circuit board 10.
The head of the device protrudes downward from the back surface of the circuit board 10 (FIG. 2).

The heat radiating member 20 is constituted by an extruded product made of aluminum or aluminum alloy in the illustrated example.

Specifically, the heat dissipation member 20 has a substantially flat body plate 21 and an outer surface (lower surface in the figure) of the body plate 21.
A large number of fins 22 formed on the upper surface of the main body plate 21 and a pair of substrate holding portions 24 protruding from both ends of the back surface (upper surface in the figure) of the main body plate 21 in the width direction.

Both substrate holding portions 24 extend parallel to the fins 22, and a substrate holding groove 24a is formed on the inner surface thereof along the longitudinal direction of the substrate holding portions 24. Both end portions in the width direction of the circuit board 10 can be inserted into the board holding grooves 24a in a direction substantially parallel to the back surface of the main body plate 21, and in the inserted state, as shown in FIG. The back surface of the substrate 10 and the back surface of the heat dissipation member 20 face each other in a substantially parallel state, and a gap is secured between the two surfaces, and an insulating paste 28 having thermal conductivity can be interposed in this gap. .

Further, an escape groove 26 parallel to the substrate holding groove 24a is formed at an appropriate position on the back surface of the body plate 21, and the head of the screw 18 is escaped into the escape groove 26 (that is, Interference between the screw head and the heat dissipation member 20 can be avoided).

The entire cover 30 is integrally formed of an insulating material such as synthetic resin, and is opened downward to form the circuit board 1.
It has a shape that covers 0 from above. Engaging claws 32 are formed on the lower end of the side wall of the cover 30, while ridges (locking parts) 27 parallel to the substrate holding part 24 are formed on both ends of the heat dissipation member 20 in the width direction. The cover 30 is locked to the heat radiating member 20 side by the engagement claw 32 riding on the protrusion 27 and going around below the protrusion 27.

The top wall of the cover 30 is provided with a pair of through holes 34 for injecting the potting agent.
An opening 36 for exposing the connector 14 to the front is provided on the front side wall of the.

This control unit can be manufactured in the following manner, for example.

1) Each circuit element including the semiconductor device 12 and the board connector 14 are mounted on one surface (on the upper surface in the figure) of the circuit board 10.

2) Apart from 1), the heat dissipation member 20 is manufactured. Since the fins 22, the substrate holding portion 24, the escape grooves 26, and the protrusions 27 of the heat dissipation member 20 shown in the drawing are all parallel and have a uniform cross section, the heat dissipation member 20 can be manufactured by extrusion molding. The heat dissipation member 20 can be mass-produced by cutting the product into an appropriate size.

3) The back surface of the circuit board 10 (the bottom surface in the figure),
In a state where the insulating paste 28 having thermal conductivity is applied to at least one of the back surface (top surface in the figure) of the heat dissipation member 20,
Both ends in the width direction of the circuit board 10 are inserted into the board holding grooves 24 of the heat dissipation member 20 from one end side thereof. Here, if an adhesive is used for the insulating paste 28, the circuit board 10 and the heat dissipation member 20 can be insulated and integrated at the same time. As the insulating paste 28, it is preferable to use, for example, silicone oil as a base containing metal powder having high thermal conductivity.

By simply performing the inserting work as described above,
It is possible to form a state in which the back surface of the circuit board 10 and the back surface of the heat dissipation member 20 are substantially parallel to each other and the insulating paste 28 is interposed between the two back surfaces (FIG. 2). Therefore, the circuit board 1
0 and the heat dissipation member 20 are extremely easy to assemble. Moreover, in this state, the back surface of the circuit board 10 is close to the back surface of the heat dissipation member 20 over the entire area thereof, so that good heat dissipation (cooling) can be performed over the entire circuit board. In particular, when the circuit board 10 having the metal board body 11 as shown in the figure is used, the heat generated by the semiconductor device 12 mounted on the front surface of the circuit board 10 can be effectively transmitted to the heat dissipation member 20 side. It will be possible.

4) The cover 30 is placed on the circuit board 10 so that the engaging claws 32 of the cover 30 are attached to the heat radiating member 2.
The cover 30 is locked to the heat radiating member 20 side by engaging with the ridge 27 of 0. After that, a potting agent is injected from one through hole 34 of the cover 30 (the other through hole 34 is used for bleeding) to seal the inside of the cover 30.

In the embodiment shown above, the circuit board 10
A gap is secured between the heat dissipation member 20 and the heat dissipation member 20 so that the insulating paste 28 exists therein. For example, the back surface of the heat dissipation member 20 is coated with a thin insulation film and the insulation film 28 and the circuit board 10 are covered. The height position of the substrate holding groove 24a may be set so as to directly contact the back surface.

[0037]

As described above, according to the present invention, a board holding groove is formed integrally with the heat dissipation member, and both ends of the circuit board are inserted into the board holding groove so that the circuit board becomes a heat dissipation member. Since it is held in a posture substantially parallel to the back surface, the facing area between the circuit board and the heat dissipation member is increased to improve heat dissipation (board cooling), and the assembly structure is simplified, and There is an effect that the mounting state of the semiconductor device is not adversely affected and the manufacturing thereof can be facilitated.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an overall configuration of a control unit according to an embodiment of the present invention.

FIG. 2 is a sectional front view showing a main part of the control unit.

[Explanation of symbols]

10 circuit board 11 Board body 12 Semiconductor devices 14 connector 15 Adhesive layer 16 Wiring pattern (wiring material) 18 screws 20 Heat dissipation member 21 Body plate 22 fins 24 Substrate holder 24a Substrate holding groove 26 escape groove 27 Protrusion (locking part) 28 Insulating paste 30 covers 32 engaging claws

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shigeki Yamane             1-7-10 Kikuzumi, Minami-ku, Nagoya-shi, Aichi             Auto Network Technical Laboratory Co., Ltd. (72) Inventor Takahiro Onizuka             1-7-10 Kikuzumi, Minami-ku, Nagoya-shi, Aichi             Auto Network Technical Laboratory Co., Ltd. (72) Inventor Isao Isshio             1-7-10 Kikuzumi, Minami-ku, Nagoya-shi, Aichi             Auto Network Technical Laboratory Co., Ltd. (72) Inventor Takahiro Asou             Sumitomo Den 1-14 Nishi-Suehiro-cho, Yokkaichi-shi, Mie Prefecture             Sozo Co., Ltd. F-term (reference) 5E322 AA11 AB06 FA04                 5E348 AA08 AA12

Claims (10)

[Claims] 1. A circuit board on which a semiconductor device is mounted, and a heat radiating member disposed so as to face a surface opposite to the mounting surface, the heat radiating member including both end portions of the circuit board. Is formed so that the circuit board is held on the heat dissipation member side in a state of being close to and substantially parallel to the back surface of the heat dissipation member in the inserted state. And control unit. 2. The control unit according to claim 1, wherein the circuit board has a metal board body, and a wiring material is arranged on the surface of the board body via an adhesive layer having an insulating property. , A control unit in which a semiconductor device is mounted on the wiring material. 3. The control unit according to claim 1, wherein a pair of board holding portions sandwiching the circuit board from both sides are formed on a back surface of the heat dissipation member, and the board holding groove is formed on an inner side surface of the board holding portion. A control unit characterized by being formed. 4. The control unit according to claim 1, wherein a gap is secured between the circuit board held by the substrate holding groove and the back surface of the heat dissipation member, and the gap has thermal conductivity. A control unit characterized by interposing an insulating paste having 5. The control unit according to claim 4, wherein the insulating paste is an adhesive. 6. The control unit according to claim 1, wherein the heat dissipation member is an extrusion molded product, and a fin parallel to the substrate holding groove is formed on an outer surface of the heat dissipation member. Control unit to 7. The control unit according to claim 6, wherein an escape groove for escaping a head of a screw, which is a groove parallel to the board holding groove and protruding to the back surface of the circuit board, is provided on the back surface of the heat dissipation member. A control unit characterized by being formed. 8. The control unit according to claim 1, further comprising a cover that covers the circuit board from a side opposite to the heat radiating member, and locks the cover on a peripheral portion of the heat radiating member. A control unit having a locking portion formed. 9. A method of manufacturing a control unit, comprising: a circuit board on which a semiconductor device is mounted; and a heat dissipation member disposed so as to face a surface opposite to a mounting surface thereof. A heat dissipation member forming step of integrally forming a heat dissipation member having a board holding groove on the back side into which both ends are inserted, and inserting the both ends of the circuit board into the board holding groove of the heat dissipation member to dissipate the heat from the circuit board. A method of manufacturing a control unit, comprising: an assembling step in which the member is held in a posture in which the member is close to the back surface and is substantially parallel to the back surface. 10. The method of manufacturing a control unit according to claim 9, wherein the heat radiation member molding step includes a step of extruding a molded body having an outer surface having the substrate holding groove and fins parallel to the substrate holding groove. And a step of cutting the molded body to an appropriate size.