JPH081998B2 - Shield case with power transistor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield case in which a power transistor suitable for a DC-DC converter or the like is mounted.

[0002]

2. Description of the Related Art DC-mounted power transistors
In order to improve heat dissipation in a DC converter etc.,
A method is adopted in which a power transistor is mounted using a shield case as a heat sink. FIG. 3 is a sectional view showing an example in which a power transistor is mounted on a conventional shield case. In FIG. 3, 1 ₁ shield case, 2
Is a lug terminal protruding from the shield case. The chip-shaped electronic component 6 is fixed to the printed circuit board 5 with the solder 9, the terminal pin 7 ₁ of the power transistor 7 is inserted into the hole of the printed circuit board 5, and the terminal pin 7 ₁ protruding from the back surface is solder 9. And is fixed to the printed circuit board 5. The power transistor 7 is adapted to be in contact with the ceiling plate of the shield case bent substantially horizontally in the terminal pin ₇₁ is a printed circuit board 5. Reference numeral 3 is a terminal pin implanted in the printed circuit board 5. Printed circuit board 5 on which the electronic components 6 and the power transistors 7 are soldered is inserted into the shield case 1 ₁ is locked by the protrusions 1 ₂ provided in the shield case 1 _1. The power transistor 7 is
The screw 8 is passed through a hole 7 ₂ provided in the power transistor 7, tightened with a nut 8 ₂ , and fixed to the ceiling plate of the shield case 1 ₁ . Then, projection back cover 4 of the metallic is provided on the back surface of the shield case 1 ₁ (not shown.) In fitted closed, the shield structure power transistor is mounted is formed.

[0003]

In the device also serves as a shield case 1 ₁ heat dissipation substrate as shown in FIG. 3 INVENTION SUMMARY is], when mounting the power transistor 7 to the shield case 1 _1,
The nut 8 ₂ is attached to the box wrench, and the nut is inserted into the hole 5 ₁ provided in the printed board 5 and fixed. On the other hand, the tip of the driver is brought into contact with the driver groove of the head of the screw 8, the tip of the screw 8 is passed through the hole 7 ₂ provided in the power transistor 7, and the nut 8 ₂ is applied. Attach the transistor 7 to the ceiling plate of the shield case 1 ₁ . Therefore, there is a drawback that the work of mounting the power transistor 7 becomes complicated and the number of work steps is increased. Furthermore, there is a disadvantage that the head of the screw 8 is the total height of projecting from the shield case 1 ₁ is increased. SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned drawbacks, and is a power transistor having a structure in which a power transistor can be easily mounted and a head of a screw for mounting the power transistor does not protrude from the shield case. The purpose of the present invention is to provide a shield case in which is mounted.

[0004]

A shield case in which a power transistor according to the present invention is mounted is formed by folding back an extension portion of at least one metal plate forming a side wall, which is formed by cutting out the shield case, into the shield case. , Bend the tip in parallel to the ceiling plate of the shield case,
Provide a tongue-shaped metal plate integrated with the shield case,
A flat plate with a tap is inserted between the tongue-shaped metal plate and the ceiling plate of the shield case, and the tongue-shaped metal plate and the power transistor are sandwiched between the flat plate and the printed circuit board. It is fixed.

[0005]

In the shield case in which the power transistor of the present invention is mounted, the power transistor and the tongue-shaped metal plate in the shield case are sandwiched between the printed circuit board and the flat plate so as to enhance the heat dissipation effect of the power transistor. At the same time, the work of attaching the power transistor is easy, and the head of the screw does not protrude from the shield case.

[0006]

1 is a view showing the outer appearance of a shield case of the present invention, and FIG. 2 is a sectional view showing an embodiment of the shield case. 1 and 2, 1 is a shield case, 2 is a lug terminal protruding from the shield case 1, 3 is a terminal pin embedded in a printed circuit board 5, and 4 is a back cover of the shield case. 6 is a chip-shaped electronic component, and 7
Is a power transistor. Reference numeral 8 is a screw for attaching the printed circuit board 5 on which the power transistor 7 and the like are mounted to the shield case 1.

In the shield case 1, the side wall of the metal plate is cut out into a long plate shape, the extended part of the metal plate is folded back inward, and the tip end thereof is bent in parallel with the ceiling plate of the shield case 1 tongue piece. Jo metal plate (hereinafter, referred to as the tongue plate) to form a 1 _3. Tongue plate 1 ₃ of the tip,
Hole 1 ₅ screws 8 penetrates is formed. Reference numeral 11 is a flat plate on which a tap 12 is formed, and the flat plate 11 is a projection 1
₄ is inserted in and fixed by engaging the projections 1 ₄ between the formed tongue plate 1 ₃ and the shield case 1 ceiling plate.
The tip of the screw 8, the printed circuit board 5 on which the electronic components 6 and the power transistors 7 of the chip-is attached, the power transistors 7 and tongue plate 1 ₃ each to form a hole 7 _2, 5
It penetrates through _{2, 15} and is screwed into the tap 12 of the flat plate 11,
Power transistors 7 and tongue plate 1 ₃ is fixed is fastened between the flat plate 11 and the printed circuit board 5 by screws 8. After that, the back cover 4 is inserted into the bottom of the shield case 1, and the back cover 4 is attached to the protrusion formed on the side wall of the shield case 1.
Are engaged with each other to form a shield structure.

By using the same material as the shield case 1 for the flat plate 11, the heat generated in the power transistor 7 is conducted not only to the side wall portion of the shield case 1 but also to the ceiling plate, and the heat dissipation is further improved. can do.

[0009]

The shield case in which the power transistor of the present invention is mounted is formed by inserting a screw from the back surface of the printed circuit board, screwing the screw into a tap provided on the flat plate, and bending the shield case. The power transistor is fixed in the shield case by fastening the three elements of the tongue plate, the power transistor, and the printed circuit board formed together, and there is an advantage that the screw head does not protrude from the shield case. Therefore, since the head of the screw does not protrude outward from the shield case, the overall height can be set low. Further, the screw is inserted from the back surface of the printed circuit board and screwed and fixed to a tapped flat plate without using a nut, which reduces the man-hours for mounting the power transistor and reduces the complexity of the conventional method. Has the effect of eliminating various assembly work.

[Brief description of drawings]

FIG. 1 is a perspective view showing an appearance of a shield case in which a power transistor of the present invention is mounted.

FIG. 2 is a sectional view showing an embodiment of a shield case in which the power transistor of the present invention is mounted.

FIG. 3 is a cross-sectional view showing an example of a shield case element in which a conventional power transistor is mounted.

[Explanation of symbols]

1 Shield Case 1 ₃ Tongue Plate 1 ₄ Protrusion 1 _5, 5 _{2, 2,} 7 _2, Hole 2 Lug Terminal Pin 3 Terminal Pin 4 Back Lid 5 Printed Circuit Board 6 Chip-shaped Electronic Component 7 Power Transistor 7 ₁ Terminal Pin 8 Screw 8 ₁ Screw head 9 Solder 11 Flat plate 12 Flat plate tap

Claims (1)

[Claims] 1. At least one of the metal plates forming the side wall of the shield case is cut out long, the metal plate is folded back into the shield case, and is bent parallel to the ceiling plate of the shield case to form a tongue shape. A flat plate that is in contact with at least one of the side wall and the ceiling plate of the shield case and has a tap formed is inserted between the tongue-shaped metal plate and the ceiling plate of the shield case. A screw penetrates through holes formed in the power transistor and the tongue-shaped metal plate, respectively, and the screw is screwed into a tap formed on the flat plate, and the tongue-shaped metal is provided between the flat plate and the printed board. A shield case mounted with a power transistor, characterized in that a plate and the power transistor are sandwiched and fixed to the shield case.