JPH1065371A - Electric part attaching structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively utilize a housing as a heat sink by preventing the impression of a force upon a soldered section. SOLUTION: A pair of holding sections 15 and 17 is formed in each of the case 11 and the cover 12 of a housing 10 housing a printed wiring board 19, and a transistor 22 is held between each pair of holding sections 15 and 17. The lead 24 of the transistor 22 is soldered to the through-hole 20 of the board 19. The header 25 of the transistor 22 is fixed to the case-side holding section 15 with a screw member 29, by screwing the member 29 in the tapped hole of the section 15 through the through-holes 18 and 21 of the holding section 17 and board 19. Therefore, the housing 10 can be utilized effectively as a heat sink, because the transistor 22 can be thermally connected to the casing 10 when the transistor 22 is held between the case 11 and cover 12, while the transistor 22 is in contact with the board 19 and at the same time, the application of an external force on the lead 24 of the transistor 22 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric component mounting structure, and more particularly to a technique for improving heat radiation performance.
For example, the present invention relates to a technology that is effective when used to attach an electric component such as a power transistor that generates a large amount of self-heat to a vehicle electrical component such as an electromagnetic relay.

[0002]

2. Description of the Related Art In general, a power transistor such as a field effect transistor (FET) is used to drive a load in an electric component of an automobile. This power transistor has a large amount of current and therefore generates a large amount of self-heating. Therefore, in a transistor (hereinafter, referred to as a transistor) used for automotive electrical components, a heat sink is attached to a sealing body of the transistor in order to enhance heat dissipation performance.

[0003] As a conventional transistor mounting structure, there is a structure in which a transistor is assembled to a case or a cover forming a housing of an automobile electrical component so that the case or the cover is effectively used as a transistor heat sink. That is, a lead of a transistor is inserted into a through hole of a printed wiring board incorporated in a housing of an automobile electrical component, and the transistor is soldered from the printed wiring board in an upright state. It is in contact with the cover and fastened with bolts and nuts. According to this transistor mounting structure, the case and the cover are effectively used as a heat sink of the transistor, so that the heat radiation performance of the transistor can be improved while avoiding an increase in the number of parts and the number of assembling steps of the automotive electrical components.

[0004]

However, in the above-described transistor mounting structure, after the transistor leads are soldered to the through-holes of the printed wiring board, the sealed body of the transistor standing upright with respect to the printed wiring board. Is fastened to the case or cover by bolts and nuts, so that the transistor may move with respect to the printed circuit board when screwing or joining the case and cover, and the movement may cause the transistor to move to the soldering part of the transistor lead. Mechanical stress may be applied.

An object of the present invention is to provide a mounting structure for an electric component that can effectively utilize a housing as a heat sink while preventing the application of mechanical stress to a soldered portion.

[0006]

According to the present invention, there is provided an electric component mounting structure according to the present invention, wherein a part of the electric component is in contact with a housing for accommodating a printed wiring board, and a screw is inserted into a mounting hole of the electric component. In the mounting structure of the electric component in which the member is inserted and fastened, and the lead of the electric component is electrically connected to the printed wiring board, a pair of sandwiching portions facing each other are provided in a part of the housing. It is formed, and the electric component is sandwiched between the sandwiching portions in a state of being in contact with the printed wiring board,
The screw member is inserted through a through hole formed in the printed wiring board, and the electric component is fastened to the other sandwiching portion.

According to the above-described means, the electric component can be thermally connected to the housing by sandwiching the electric component with a part of the housing in a state where the electric component is in contact with the printed wiring board. Can be released very effectively, and the housing can be effectively used as a heat sink for electric components. Moreover,
Since the electrical component is held between a part of the housing in a state of contact with the printed wiring board, the electrical component does not shift when the electrical component is fastened to the housing as a heat sink with a screw member. It is possible to prevent mechanical stress from being applied to the soldered portion to the printed wiring board, thereby preventing deterioration in quality and reliability.

[0008]

1A and 1B show a mounting structure of a transistor according to an embodiment of the present invention, wherein FIG. 1A is a partially omitted front sectional view, and FIG. 1B is an enlarged view of a portion b of FIG. It is a partial sectional view. 2A is a partially cut side view, and FIG. 2B is a partially cut plan view.

In the present embodiment, the mounting structure of an electric component according to the present invention is configured as a mounting structure of a transistor in which a transistor is mounted on a housing of an automobile electrical component and the housing is effectively used as a heat sink. A housing (hereinafter, referred to as a housing) 10 of an automobile electric component includes a case 11 and a cover 12, and the case 11 and the cover 12 are made of a material having good heat conductivity such as iron or aluminum, and are pressed. Each is integrally molded. The case 11 is formed in a box shape whose plane shape is rectangular and has a deep bottom with an open lower surface.
The cover 12 is formed in a box shape having a planar shape substantially equal to the case 11 and a shallow bottom with an open upper surface. A case-side flange 13 is bent radially outward at a right angle at a lower end opening edge of the case 11, and a cover-side flange 14 is bent radially outward at an L-shape at an upper end opening edge of the cover 12. I have.

A case-side sandwiching portion 15 is formed at one end of the ceiling wall of the case 11 so as to bulge in the opening direction. That is, the case side sandwiching portion 15 is
One end of the ceiling wall is integrally plastically deformed by pressing in the opening direction. The case-side sandwiching portion 15 is arranged at the center of one end of the case 11, and has a trapezoidal deep groove shape with an open end. A screw hole 16 in which a female screw can be formed is integrally formed at one end of the case-side sandwiching portion 15 by burring. At one end of the bottom wall of the cover 12 facing the case-side sandwiching portion 15, a cover-side sandwiching portion 17 is formed so as to bulge in the opening direction. That is, the cover side sandwiching portion 17 is
One end of the bottom wall is integrally plastically deformed by press working in the opening direction. The cover-side sandwiching portion 17 is arranged at the center of one end of the cover 12 and has a trapezoidal shallow groove-shaped cross section with one end opened. A through-hole 18 through which a screw member can be inserted is formed at one end of the cover-side sandwiching portion 17.

The housing 10 has a built-in printed wiring board 19 on which various electric components (not shown) for constituting electric components of the vehicle are mounted. That is, the printed wiring board 19 is placed on the cover-side flange 14 so as to close the opening of the cover 12. Subsequently, after the case 11 is covered, the cover-side flange 1
The case 11, the cover 12, and the printed wiring board 19 are fastened together by caulking so that the 4 engages with the case-side flange 13. Printed wiring board 1
9 has a through hole 20 for electrically connecting the transistor 22 and a through hole 21 for mechanically connecting the transistor 22.

The transistor 22 includes a semiconductor chip (not shown) in which a transistor circuit is formed, a sealing member 23 for sealing the semiconductor chip with a resin, and one end protruding from one end of the sealing member 23. It comprises a book lead 24 and a rectangular plate-shaped header 25 embedded in one main surface of the sealing body 23 to constitute a primary heat sink (heat radiating plate). In the header 25, a mounting hole 26 for fixing the transistor 22 itself to a printed wiring board or the like is provided in the thickness direction.

Next, a method of assembling the transistor 22 to the printed wiring board 19 and the housing 10 will be described.
This description clarifies the details of the configuration of the transistor mounting structure according to the present embodiment.

The transistor 22 is connected to the printed circuit board 19
As shown in FIG. 1, each of the leads 24 of the transistor 22 has a hairpin curve shape at its intermediate portion, and the leading end 24a of the lead 24 and the sealing body 23 are perpendicular to each other. Be bent. The hairpin curve-shaped portion formed in the intermediate portion of the lead 24 forms a displacement absorbing portion 27 that absorbs displacement between the tip portion 24a of the lead 24 and the sealing body 23 to reduce mechanical stress. ing.

Thereafter, each lead 24 of the transistor 22
Are respectively inserted into the through holes 20 of the printed wiring board 19, subjected to soldering processing, and fixed by the soldering portions 28. By soldering the group of leads 24 to the group of through holes 20, the transistor 22 is electrically connected to each electric component mounted on the printed circuit board 19 via electric wiring (not shown) of the printed circuit board 19. It will be in the state that was done. In addition, the sealing body 23 of the transistor 22 comes into contact with the case-side main surface (hereinafter, referred to as the upper surface) of the printed wiring board 19, and the mounting hole 26 faces the through hole 21.

The printed wiring board 19 to which the transistor 22 is fixed is placed on the cover-side flange 14 so as to close the opening of the cover 12. At this time, the end of the printed wiring board 19 on the side where the transistor 22 is soldered is disposed on the end of the cover 12 on the side where the cover-side sandwiching portion 17 is formed. With this arrangement, the mounting hole 26 of the transistor 22 and the through hole 21 of the printed wiring board 19 are
Now you are facing 8.

Next, the case 11 is put on the cover 12 so as to entirely cover the printed wiring board 19.
At this time, the end of the case 11 where the case-side sandwiching portion 15 is formed is connected to the cover-side sandwiching portion 17 of the cover 12.
Is arranged at the end on the side where the is formed. With this arrangement, the mounting hole 26 of the transistor 22, the through hole 21 of the printed wiring board 19, and the through hole 18 of the cover side sandwiching portion 17 face the screw hole 16 of the case side sandwiching portion 15. Become.

Subsequently, the case 11, the cover 12, and the printed wiring board 19 are fastened together by swaging the cover-side flange 14 so as to hold the case-side flange 13. By this joint fastening, the transistor 22 is sandwiched between the lower surface of the case-side sandwiching portion 15 and the upper surface of the cover-side sandwiching portion 17. In this state, the header 25 of the transistor 22 comes into contact with the case 11, so that the transistor 22 is thermally connected to the case 11. Therefore,
Case side sandwiching portion 15 and cover side sandwiching portion 17
It is desirable that the transistor 22 be set so that the transistor 22 can be sandwiched exactly when the case 11 and the cover 12 are coupled to each other.

Thereafter, a self-tapping screw member 29 as a male screw member is inserted into the through hole 1 of the cover side sandwiching portion 17.
8. Inserted into the through hole 21 of the printed wiring board 19 and the mounting hole 26 of the transistor 22, and screwed into the screw hole 16 of the case side sandwiching portion 15. By this screwing, the header 25 of the transistor 22 is brought into close contact with the upper surface of the case-side sandwiching portion 15, so that the transistor 22
Thermal connection to the case 11 is further ensured.

When the transistor 22 is fastened to the screw hole 16 by the self-tapping screw member 29, even if the transistor 22 is displaced with respect to the printed wiring board 19, the displacement formed on the lead 24 of the transistor 22 is absorbed. Since the displacement is absorbed by the elastic deformation of the portion 27, the mechanical stress caused by the displacement causes the soldering portion 2 formed on the distal end portion 24 a of the lead 24.
8 will not join. Therefore, it is possible to prevent a defect such as a crack from occurring in the soldered portion 28 due to the mechanical stress.

According to the transistor mounting structure configured as described above, the heat thermally conducted to the header 25 of the transistor 22 propagates to the case-side sandwiching portion 15 that is thermally connected to the header 25, and the case 11 Spread throughout.
Since the case 11 has an extremely large heat capacity, the heat dissipation efficiency of the transistor 22 is extremely high. Also, the header 25 of the transistor 22 is connected to the case side
Since the self-tapping screw member 29 is in close contact therewith, the heat transfer efficiency to the case-side sandwiching portion 15 is also very good.

It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the scope of the present invention.

Transistor 22, printed wiring board 1
The order of assembling the 9, the cover 12, and the case 11 is not limited to the above embodiment. For example, in case 11, the transistor 22
After the screws are screwed, the case 11 and the cover 12 may be combined. In this case, the through hole 18 of the cover 12 can be omitted.

The transistor 22 is not limited to being thermally connected to the case 11 but may be connected to the cover 12. In short, the transistor 22 may be connected to a part of the housing 10.

The displacement absorbing portion 27 of the lead 24 is not limited to being formed in advance before the printed wiring board 19 is inserted into the through hole 20, but may be formed after the tip portion 24a of the lead 24 is inserted into the through hole 20 or by soldering. After forming, it may be formed by bending.

In the above embodiment, the case where the transistor is thermally connected to the housing has been described.
The present invention is not limited to this, and can be applied to the entire mounting structure for electric components. In particular, the present invention can be applied to a mounting structure of a self-heating electric component such as a power transistor or a power IC to obtain excellent effects. Further, the housing is not limited to the housing of the automobile electric component.

[0027]

As described above, according to the present invention,
Since the electric component can be thermally connected to the housing by sandwiching the electric component with a part of the housing in a state of being in contact with the printed wiring board, the heat of the electric component can be released very effectively. At the same time, the housing can be effectively used as a heat sink for electric components. Moreover, since the electric components are sandwiched by a part of the housing in a state in which the electric components are in contact with the printed wiring board, the electric components do not shift when fastening the electric components to the housing as a heat sink with a screw member. Since it is possible to prevent mechanical stress from being applied to a soldered portion of the electric component to the printed wiring board, it is possible to prevent deterioration in quality and reliability.

[Brief description of the drawings]

FIGS. 1A and 1B show a mounting structure of a transistor according to an embodiment of the present invention, wherein FIG.
(B) is an enlarged partial sectional view of a part b of (a).

2A is a partially cut-away side view, and FIG. 2B is a partially cut-away plan view.

[Explanation of symbols]

10 housing, 11 case, 12 cover, 13
... case side flange, 14 ... cover side flange, 15 ...
Case side sandwiching part, 16 ... screw fixing hole, 17 ... cover side sandwiching part, 18 ... through hole, 19 ... printed wiring board,
Reference Signs List 20: Through hole, 21: Through hole, 22: Transistor, 23: Sealing body, 24: Lead, 24a: Tip, 2
5 ... Header, 26 ... Mounting hole, 27 ... Displacement absorbing part, 28 ...
Solder part, 29: Self-tapping screw member (screw member).

Claims (3)

[Claims] In a state in which a part of an electric component is in contact with a housing in which a printed wiring board is stored, a screw member is inserted into a mounting hole of the electric component and fastened. In a mounting structure for an electric component in which leads are electrically connected to the printed wiring board, a pair of sandwiching portions facing each other is formed in a part of the housing, and the electric component is connected to the printed wiring board between the sandwiching portions. The electric component is sandwiched in a state of being in contact with the substrate, and the screw member is inserted into a through hole formed in the printed wiring board, and the electric component is fastened to the other sandwiching portion. Parts mounting structure. 2. The method according to claim 1, wherein the housing is formed by a case and a cover which are fitted to each other in the middle, and the pair of sandwiching portions are formed by bulging at opposing portions of the case and the cover. The mounting structure for an electric component according to claim 1. 3. The electric component according to claim 1, wherein a displacement absorbing portion is formed in the middle of the lead of the electric component.
The mounting structure of an electric component according to the item.