GB2052164A

GB2052164A - Assemblies of electrical components

Info

Publication number: GB2052164A
Application number: GB7922814A
Authority: GB
Original assignee: Burroughs Corp
Current assignee: Unisys Corp
Priority date: 1979-06-30
Filing date: 1979-06-30
Publication date: 1981-01-21
Also published as: GB2052164B

Abstract

A mounting system for the rapid replacement of heat generating electrical devices comprises a plurality of device bearing heatsink assemblies 6 manually removably held in a rack assembly 4, electrical connection to the device or devices on each assembly being via a manually removable multiple connector 3, the replacement of a device or devices being accomplished by the replacement of the heatsink assembly on which the device or devices is located. <IMAGE>

Description

SPECIFICATION Improvements in or relating to assemblies of electrical components This invention relates to assemblies of electrical components and it is an object of the invention to provide an assembly of a heat generating device and its associated heat sink which is readily removable from any circuit arrangement in which it is incorporated.

The term 'heat generating device' is used primarily to indicate active electronic components such as power transistors, Triacs, thyristors, and the like which, in operation, generate more heat than they dissipate without the addition of means for conducting or radiating the heating away from the device. However, the term is also used to include passive electrical components such as resistors which again are operated at such high currents that their temperature would rise unduly unless means were provided for conducting or radiating the heat generated.

Similarly the term 'heat sink' is used herein to define any device such as a metal plate which is specially designed to conduct and/or radiate heat from an electrical component. Heat sinks may, in particular, be provided with fins and coloured matt black to enhance radiation.

From one aspect the invention consists in an assembly comprising a heat sink, a heat generating device and a multiple connector adapted to provide a plurality of electrical connections to said heat generating device, wherein both said heat generating device and said connector are mounted on said heat sink.

As already mentioned, the heat generating device may be, for example, a power transistor.

The heat sink may consist, for example, of a metal plate provided with a plurality of fins extending in both directions at right-angles to the plate. In one particular embodiment, the plate includes a central strip, in which the power transistor and the multiple connector are mounted, and two sets of fins, one located on each side of said central strip.

In one embodiment the connector is in the form of an insulated block provided with a plurality of electrically conductive pins each connected by means of a wire to a respective electrode of the transistor. In this case, a mating socket is also provided to make contact with the pins, said socket being connected through a harness to the host equipment in which the power transistor is incorporated. The host equipment may be, for example, a computer or a peripheral device for use with a computer.

In another embodiment the transistor is plugged directly into the multiple connector which is provided with a captive harness terminating in a socket which can be connected either directly or indirectly to the host equipment. In this case the multiple connector is preferably located on the opposite face of said central strip from the transistor, suitable apertures being provided in said central strip through which pins on the transistor pass to engage in suitable sockets in the connector. Preferably mounting screws also pass through further apertures in said central strip to secure the transistor to the connector.

Heat generating devices such as power transistors provided with heat sinks are already known.

However, it is usual for the ele'ctrical connections to the electrodes of the transistor to be soldered to the printed circuit board, or the like, in which the heat sink is mounted. Consequently replacement of a power transistor may be time-consuming and hence costly.

The usual routine when changing a heat sink mounted power device is firstly, to unscrew the heat sink, secondly, to unsolder the power device, thirdly, to unscrew the power device, fourthly, to reassemble the insulation and thermal contact devices onto a new power device, fifthly, to screw on the new power device, sixthly, to solder the new power device, and seventhly, to screw the heat sink back in place. This is very timeconsuming.

On the other hand, if an assembly in accordance with the invention is used, it is only necessary to uncouple a plug and socket connection. remove the assembly complete with the power device, and replace it by a new assembly with a new power device.

To increase further the advantages of the invention, it is preferred that each assembly is mounted in a rack or the like and held in position either by gravity alone or, if necessary, with the addition of a simple clip.

In an advantageous embodiment of the invention, a plurality of assemblies are mounted in a rack which is preferably in the form of a box which is open at the top and at the bottom to allow the passage of air past the fins of the heat sinks.

It will be understood that an assembly in accordance with the invention has many advantages over the prior art, in particular, in that it may be arranged that no unscrewing is required to remove a heat sink, no desoldering or soldering is required to change power devices, and hence very fast and easy maintenance is obtained.

From another aspect the invention consists in any features of novelty, taken singly or in combination, of the assembly illustrated in Figure 1 or Figure 3 of the accompanying diagrammatic drawings, or of the rack-mounted plurality of assemblies iliustrated in Figure 2.

The assembly illustrated in Figure 1 includes a power transistor 1 fixed to a heat sink 2. A metal plug connector 3 is electrically connected to the respective electrodes of the transistor by wires 8.

It will be seen that the heat sink includes a main plate 9 having a central area 6 on which the transistor 1 and the connector 3 are mounted. On either side of the central area are three vertical fins 7. The power transistor 1 can be electrically connected to a host computer, or like device, by means of a socket designed to mate with the plug connector 3, and having a harness leading to the host device.

Figure 2 shows a rack holding a plurality of assemblies as illustrated in Figure 1. The assemblies are mounted with the main plates 9 vertical in a box-like rack 4. The rack is open at the top and bottom so that air can circulate past the fins 7 of the various assemblies by convection. If desired, a fan may be provided to force air past the fins. The individual assemblies are retained by gravity in heat sink guides 5. If desired, clips (not shown) may be provided as an additional retaining means.

The power transistor 1, the heat sink 2, and the connector 3 are provided as a complete assembly.

When it is required to change the power transistor, all that is necessary is to unplug the relevant assembly, remove it from the heat sink mount, insert a new assembly, and reattach the connector.

It is, of course, to be understood that, if desired, more than one heat generating device may be provided in each assembly.

Figure 3 shows a modified embodiment of the invention in which the transistor is plugged directly into the multiple connector. As can be seen from the drawing, the multiple connector is located on one side of the heat sink and the transistor is located on the other side. The multiple connector is provided with threaded bushes to receive mounting screws which pass through appropriate holes in the transistor mounting and corresponding holes in the heat sink. The transistor pins also pass through hole#s in the heat sink to fit in respective sockets in the multiple connector. A captive harness is fitted to the multiple connector which terminates in a socket which can be connected to the host equipment.

The procedure for removing the transistor is as follows: 1) remove the complete assembly from the mounting rack; 2) remove the two mounting screws; 3) unplug the transistor; 4) plug in the replacementtransistortogether with its thermal contact devices; 5) replace the mounting screws; and 6) replace the assembly in the mounting rack.

Claims

1. A system for mounting heat generating electrical devices comprising; a heatsink for holding one or more of said devices and for dissipating the heat generated therein, holding means for supporting said heatsink in a predetermined position and with which said heatsink is manually engagable and disengagable, and connection means which is manually engagable to provide electrical connection to said device or devices and manually disengagable to allow for the physical removal therefrom of said heatsink complete with said device or devices.

2. A system according to claim 1 wherein said heatsink comprises a flat plate for securing said device or devices thereon and one or more fins for transferring heat from said plate to air.

3. A system according to claim 2 wherein said holding means comprises a pair of channels adapted to engage portions of one pair of opposite edges of said plate.

4. A system according to claim 3 wherein said channels are adapted for the retention of said heatsink by gravity.

5. A system according to claim 2, 3 or 4 adapted to allow for the passage of air about said heatsink.

6. A system according to any of the preceding claims wherein said holding means comprises manually engagable and disengagable clip means for retaining said heatsink.

7. A system according to any of the preceding claims wherein said connection means comprises a multiple electrical plug and a complementary multiple electrical socket.

8. A system according to claim 7 wherein said socket is secured to said heatsink.

9. A system according to claim 7 wherein said plug is secured to said heatsink.

10. A system according to any of the preceding claims wherein said device or devices are active semiconductor device or devices.

1 A system substantially as described with reference to the accompanying drawings.