GB2174240A

GB2174240A - Transistor heatsinking assembly

Info

Publication number: GB2174240A
Application number: GB8510163A
Authority: GB
Inventors: John Philip Lincoln Binns
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-04-22
Filing date: 1985-04-22
Publication date: 1986-10-29
Also published as: GB8510163D0

Abstract

A transistor heatsinking assembly comprising a mounting bracket 1 with transistor fixing means and incorporating a tongue and an enclosure 6 with at least one groove on an internal wall such that when the tongue slides in the groove the bracket is held against the internal wall. <IMAGE>

Description

SPECIFICATION Transistor heatsinking assembly This invention relates to a transistor heatsinking assembly.

Heatsinks are used in electronic systems for conducting heat from an electrical or electronic device or component and transferring it to the surrounding air via a relatively large surface area. A common form of heatsink is a finned metal plate to which the transistor is attached using a bolt which passes through a hole in the heatsink and a hole in the transistor casing. Very often the heatsink forms part or all of the wall of an enclosure and the transistor is bolted to it.

This system of mounting power transistors, however, means that the wall of the enclosure must be pierced to allow the transistor to be mounted on it thus allowing ingress of moisture into the electronics. Moreover it means that the power transistor is assembled as part of the enclosure whilst the remainder of the electronics may be assembled on a circuit board. Thus the complete electronic circuit cannot be tested until the circuit board has been assembled into the enclosure and linked to the power transistor.

According to the present invention there is provided a bracket with transistor mounting means which has a tongue on it where the base of the tongue is narrower than the body of the tongue and an enclosure where at least one interior wall has a groove whose aperture in the face of the wall is narrower than the body of the groove such that the tongue the bracket may slide into the groove on the wall and in which position the bracket may have relatively little motion possible in a direction perpendicular to the face of the wall. In an alternative form of this invention the tongue may be on the interior of the box and the groove may be in the bracket.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which: Figure 1 shows the end elevation of a power transistor in the mounting bracket.

Figure 2 shows a plan view of the assembly shown in Fig. 1.

Figure 3 shows the other plan view of the assembly shown in Figs. 1 and 2.

Figure 4 shows the mounting of the bracket and power transistor in a box section enclosure, the dovetail tongue resting in a dovetail groove.

Figure 5 shows the mounting of the bracket with power transistor in the box section enclosure with the bracket attached to a printed circuit board.

Referring to the Figs. 1, 2 and 3 the bracket has mounted in it power transistor 2 using screws 3 and nuts 4. The bracket includes holes 5 which are larger than the heads of the screws 3 to facilitate insertion of the screws into the assembly.

Fig. 4 shows enclosure 6 which is a finned aluminium extrusion box section with flat end plates the nearest one of which is removed for visibility and mounted in it is bracket 1 with power transistor 2. Retention of the bracket in the groove is by means of the end plates.

Fig. 5 shows the same enclosure with the heatsink bracket mounted on a printed circuit board 7 and slots in the interior of the enclosure for mounting the printed circuit board such that as the dovetail tongue on the bracket slides into the dovetail groove in the wall of the enclosure, the printed circuit board 7 slides into slots in the walls of the enclosure.

Claims

1. A transistor heatsinking assembly comprising a mounting bracket with transistor fixing means and incorporating a tongue and an enclosure with at least one groove on an internal wall such that when the tongue slides in the groove the bracket is held against the internal wall.

2. A transistor heatsinking assembly as claimed in claim 1 where the width of the aperture of the groove in the face of the wall is narrower than the width of the rest of the groove.

3. A transistor heatsinking assembly as claimed in claims 1 and 2 where the tongue is on the wall and the groove is in the mounting bracket.

4. A transistor heatsinking assembly as claimed in claims 1 to 3 where the shape of the tongue matches or substantially matches the shape of the groove.

5. A transistor heatsinking assembly as claimed in claims 1 to 4 where the enclosure is externally finned.

6. A transistor heatsinking assembly as claimed in claims 1 to 5 where the enclosure is an aluminium extrusion with end plates.

7. A transistor heatsinking assembly as claimed in claims 1 to 6 where the enclosure contains internal support slots for mounting a printed circuit board located such that when the bracket is mounted on the printed circuit board and the tongue on the transistor heatsinking assembly is sliding in the groove the printed circuit board may also slide in its support slots.

8. A transistor heatsinking assembly substantially as described herein with reference to the accompanying drawings.