JPH0625977Y2 - Printed board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] The effective area of a printed circuit board is expanded by using a heat dissipation plate of a heat generating element as a part of a ground pattern of the element.

[Industrial application field]

The present invention relates to a printed circuit board having a heat dissipation plate as a part of an earth pattern.

[Conventional technology]

A heat generating element such as a power transistor needs to dissipate heat using a heat dissipation plate. For example, as shown in FIG. 2, a heat dissipation plate of a type that is fixed to a printed circuit board and transfers heat to the housing is screwed into two screw holes 11 of the printed circuit board 1. The printed circuit board of this example shows a pattern capable of mounting three power transistors, 12 is an independent circuit pattern, 13 is a common ground pattern, and 14, 15 and 16 are base (B) and collector (C), respectively. , And the terminal hole of the emitter (E).

[Problems to be solved by the invention]

Since the ground pattern 13 is a large current pattern, in order to reduce the pattern resistance and the voltage drop, (1)
It is necessary to widen the pattern width on the board or thicken the copper foil of (2) pattern.

However, the method (1) reduces the mounting area of components, and thus the size of the board cannot be reduced. Further, the method (2) has a drawback that the substrate cost increases.

The present invention seeks to expand the effective area of a printed circuit board by using a heat sink as a part of the ground pattern.

[Means for solving problems]

The printed circuit board of the present invention is provided with a plurality of legs of a heat radiating plate to which the heat generating element is fixed, and a predetermined one of the legs is attached to the substrate and connected to the ground pattern, and the other predetermined legs of the legs are connected. It is characterized in that it is connected to the terminal in the vicinity of the terminal to be connected to the ground of the heat generating element.

[Action]

If the heat sink is used as a three-dimensional pattern and a part of the ground pattern, the number of plane patterns on the printed circuit board can be reduced, and the effective area can be expanded accordingly. Generally, the heat sink is made of aluminum, but if it is made of copper, the heat resistance and electric resistance can be made sufficiently small, so that the resistance of the ground pattern is lowered and the voltage drop can be reduced.

〔Example〕

FIG. 1 is a configuration diagram showing an embodiment of the present invention, (a) is a perspective view of a mounted state, and (b) is a rear view of a printed circuit board. The heat radiating plate 2 has mounting legs 21 at both ends, and the screw holes 22 thereof are aligned with the screw holes 11 of the printed circuit board 1 and screwed. Three power transistors 3 are screwed to the heat sink 2. Reference numeral 31 is the screw hole, and reference numerals 32, 33 and 34 are terminals of the base (B), collector (C) and emitter (E). These terminals 32 to 34 are inserted into the holes 14 to 16 of the printed board 1 and soldered on the back surface. still,
The substrate 1 in (a) shows the front surface, and the substrate 1 in (b) shows the back surface.

Two legs 23 for the ground pattern are provided in the middle of the heat radiating plate 2, which are inserted into the holes 17 of the printed board 1 and soldered on the back surface. This hole 17 is connected to the hole 16 by a ground pattern 13 'on the printed circuit board. Therefore,
A ground current flows through a path (indicated by a dashed arrow) from the terminal 34 of the transistor 3 to the ground pattern 13 ′ to the heat sink 2 to the ground pattern 13.

By incorporating the heat sink 2 into a part of the ground pattern in this manner, the ground patterns 13, 13 'on the printed circuit board 1 side are provided.
Even if the total area is small, the pattern resistance can be reduced, and the positions of the terminal holes 14 and 16 can be brought closer to the end portions of the substrate by that amount (the distance 2a in FIG. 2 can be halved to the distance a).

In addition, the screw hole 11 of the printed circuit board 1 is connected to the ground pattern 1
Since it can be included in No. 3, this portion is not a dead space as shown in FIG. 2, and the degree of freedom in pattern design is increased.

[Effect of device]

As described above, according to the present invention, since the heat dissipation plate of the heat generating element such as the power transistor is incorporated in a part of the ground pattern, the effective area of the printed circuit board can be expanded, the degree of freedom in pattern design can be increased, Can be miniaturized.

[Brief description of drawings]

 FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is an explanatory view of a conventional printed circuit board.

Claims (1)

[Scope of utility model registration request] 1. A ground pattern (13) in which a predetermined leg (21) of the legs of a heat sink (2) having a plurality of legs (21, 23) and to which a heat generating element (3) is fixed is attached to a substrate. ), And another predetermined leg (23) of the leg is connected to the terminal (34) in the vicinity of the terminal (34) to be connected to the ground of the heat generating element (3). Characterized printed circuit board.