GB2139006A - Modules for printed circuit boards - Google Patents

Abstract

A module intended to contain electronic components mounted on printed circuit boards has a removable tray (50) in its base, the tray including electrical connectors (52) into which the printed circuit boards or a power pack of the module may be inserted to make electrical contact therewith, the lateral edges of the tray being resiliently urged against a supporting surface of the module by spring loaded plates (56) arranged on the side of the tray remote from the supporting surface. <IMAGE>

Description

SPECIFICATION Improvements in and relating to modules The present invention concerns improvements in and relating to modules, particularly but not especially modules for mounting electrical and electronic equipment.

The term module when used herein is intended to define a box-like construction in which, for example, electrical and electronic equipment such as power packs and printed circuit boards, may be mounted, the module being adpated for fitment in a rack or rail system in such a manner that it may be disconnected and then removed therefrom for servicing or replacement.

Normally it is desirable that any heat generated in the electrical or electronic components mounted in a module may be readily dissipated therefrom and to satisfy this requirement modules are often provided with heat exchange surface over which an external cooling medium may be passed.

The present invention is particularly applicable to modules intended to accommodate printed circuit boards of standard dimensions, the said modules having a standard internal transverse dimension which is slightly greater than the thickness of a standard printed circuit board, the facing internal walls of the module delimiting said dimension each being provided with a plurality of castellations whose projection into the module interior is such that the lateral edge portions of a printed circuit board may rest against and be supported by faces of the castellations perpendicular to said facing internal walls.

Our co-pending U.K. Patent Application No.

7904302 relates to mounting means for a printed circuit board comprising a support for the board, that is castellations, and at least one sheet of a heat conductive material arranged alongside the board and a heat sink in thermal communication with said sheet.

Conveniently the heat sink is provided by the material from which the module casing is formed and the sheet of heat conductive material, or absorber, is held at its edges against the face of a castellation adjacent to the castellation against which the printed circuit board is held.

A module of the type described above will be referred to hereinafter as a "module of said type".

According to the present invention there is provided means for mounting an absorber in a module of said type, said means comprising a spacing strip associated with a pair of opposite edges of the absorber and having one side adapted for direct or indirect contact with a face of a first castellation and a plurality of resilient means protruding from the opposite side and adapted to contact said absorber to urge it away from said strip and into contact with a face of a further castellation spaced from said first castellation.

Preferably said resilient means are coil springs accommodated in cylindrical recesses formed in the said opposite side of the strip. The number of coil springs is determined by the force required to urge the absorber into contact with the face of said other castellation.

Preferably the strip is connected to the absorber at said opposite side thereof by means of fixing screws supported in the strip and along which the absorber may slide. Conveniently certain areas of the edge portions of the absorber may be deformed to provide lugs whose surface lies in a plane spaced from the plane of the absorber, the lug being provided with a through passage through which a screw may slide.

Further according to the present invention there is provided for use in a module of the said type a pair of end plates adapted for fitment between a pair of castellations, said end plates each being provided with similar castellations whereby a module designed to accommodate a plurality of printed circuit boards and absorbers in a transverse orientation may be readily converted to accommodate a plurality of printed circuit boards and absorbers in a longitudinal orientation. In a modification only one castellated plate may be employed, one of the module ends being already provided with castella tions corresponding to the castellations on said plate.

According to another aspect of the present invention there is provided a module having a removable tray including electrical connectors into which the printed circuit boards or power pack of the module may be inserted to make electrical connection therewith, each lateral edge of the tray being resiliently urged against a supporting surface of the module by a plate arranged on the side thereof remote from said supporting surface, each plate being urged towards the tray by a plurality of resilient means.

Preferably the resilient means are coil springs accommodated in recesses in a member arranged beneath said plate. Means may be provided for fixing the tray in the module and it is preferable that seal means are provided between an end plate of the tray and the module, the end plate closing off an aperture in the module for receiving the tray.

Still further according to present invention there is provided fixing means for holding a member in a module of said type, the fixing means comprising two pairs of co-operating slides arranged on either side of the member the abutting surfaces of the slides being inclined such that relative longitudinal movement of said members results in an increase in the transverse dimension of the pair of slides, which increase is utilised to fix said member against the end of the module or the face of a castellation.

Preferably one of said slides is fixed relative to the module and the other is movable and screw means interconnecting said movable slide and the module provide said longitudinal movement.

An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a cross-sectional end view through a module; Figure 2 is a top plan of the module partly in section; Figure 3 is an exploded isometric view of a module; Figure 4 is a sectional end elevation of part of a module; and Figure 5 is a plan of the part shown in Figure 4.

A A module comprises a cast aluminium alloy open-topped box 10 having cooling fins 12 formed integrally therewith at one end. The internal facing walls of the module are provided with corresponding equally spaced castellations 14 and the box is enclosed by a top plate 16. The dimensions of the module are such that standard printed circuit boards can be inserted therein through the open top and it is intended that the lateral edges 18 of each board 20 abut corresponding faces of opposed castellations.

An absorber plate 22, (only some of which are shown in Figures 1 and 2) which is manufactured from a thermally conductive material, for example aluminium alloy and has dimensions similar to the printed circuit board is arranged facing the printed circuit board and abutting the opposite faces of the neighbouring pair of opposed castellations 14. It is important that absorber plates 22 are held in close contact with the faces of the castellations 14 such that heat given off by the components of the printed circuit board is taken in by the absorbers and conducted to the castellations 14, thereafter being conducted along the walls of the module to the cooling fins 12.To this end there are provided clamping strips at each side of the absorber, each strip 24 including locating screws 26 passing through holes in the absorbers 22 in such a manner that the absorber may move relative to the screws, and a plurality of cylindrical recesses 28 each accommodating a coiled helical spring 30, the protruding outer end of which abuts the absorber and urges it away from the strip 14 against the face ofthe castellation 14. The clamping force required to give adequate thermal conduction may be achieved by increasing or decreasing the number of helically coiled springs 30 in the pre-drilled recesses 28.

To accommodate the head of the screws 26 certain portions at the lateral edges of the absorbers are cut and deformed into an L-shape lug shown in the drawings at 32.

It will be realised that a printed circuit board can be inserted into the module and positioned with its lateral edges against a castellation and thereafter an absorber with its spring urged strips 24 attached at its lateral edges may be pushed into the space between adjacent castellations to sandwich the printed circuit board between the corresponding faces of one pair of opposed castellation and the strips while at the same time the edges of the absorber are urged into close thermal contact with the facing faces of the pair of adjacent castellations Thus this aspect of the invention provides for the firm but removable location of a printed circuit board and absorber and an adequate thermal contact between the absorber and the castellations it contacts.

Figure 3 shows an exploded isometric view of a module incorporating certain modifications over that shown in Figures 1 and 2. For example there are shown a pair of opposed end plates 40 each having castellations 42 thereon which, like the castellations 14 of the module, are equally spaced. The plates 40 are so designed that they can be inserted into the module between castellations at the ends thereof thereby converting the module from one which accepts printed circuit boards and absorbers in a transverse orientation to one which accepts printed circuit boards and absorbers in a longitudinal orientation. Fixing devices similar to those described with reference to Figures 1 and 2 for the printed circuit boards and absorbers may be utilised with the end plates 40 in a manner similar to that described above.

Figure 3 shows also an end plate 46 for the module which includes locking handles 48 utilised to lock the module into its rack. Figure 3 shows also that the module is provided with a tray 50 adapted to receive a mother board" 52 which carries the electrical connections (not shown) for the printed circuit boards the arrangement being such that the tray with the mother board thereon is slid into the module by way of an end opening 54, the printed circuit board and absorbers being inserted thereafter in the manner described above, and the printed circuit boards when pushed fully downwards engaging with the electrical connections on the mother board 52.

To ensure the correct positioning and fit of the tray 50 the module is provided with fixing means similar to those described with reference to Figures 1 and 2, the said means comprising a pair of spring urged plates 56 mounted to the module at the sides thereof and adapted to contact the underside of the tray 50.

Each strip operates in conjunction with a member 58 having a plurality of cylindrical recesses therein the recesses intended to accommodate coiled helical spings 60 which serve to urge the plate 56 upwards against the bottom face of the tray. As before, the correct compressive spring force can be obtained by varying the number of springs 60.

Figures 4 and 5 show another fixing means which may be utilised for printed circuit boards and absorbers but is preferably utilised for holding a power pack or a connector board rigidly in place in the module. This fixing means comprises two pairs of slides 70,72 one pair being arranged at each side of the module between the end faces thereof and the end-most of the castellations 14. The contacting faces of the slides 70,72 are inclined with respect to their other parallel faces such that by moving one slide longitudinally relative to the other a wedging action is obtained. A fixing screw 74 passing through a slot 76 in the member 72 provides for location and an adjustment screw 78 rotatably mounted in a lug 80 is fixed to the module and engaged in the slide 72 so that on rotation of the screw 78 longitudinal movement of the member 72 serves to increase or decrease the wedging action.

It is possible to control the internal temperature of the module by regulating the temperature of the cooling fluid passing over the fins 12.

Various modifications can be made to the invention described above.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particularly importance it should be understood that the applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to whether or not particular emphasis has been placed thereon.

Claims (4)

1. Mounting means for an absorber in a module of said type, said means comprising a spacing strip associated with each edge of a pair of opposite edges of the absorber and having one side adapted for direct or indirect contact with a face of a first castellation and a plurality of resilient means protuding from the opposite side and adapted to contact said absorber to urge it away from said strip and into contact with a face of a further castellation spaced from and facing said first castellation.

2. Mounting means as claimed in claim 1, in which said resilient means are coil springs accommodated in cylindrical recesses formed in the said opposite side of the strip.

3. Mounting means as claimed in claim 2, in which the number of coil springs is determined by the force required to urge the absorber into contact with the face of said other castellation.

4. A module as claimed in any one of claims 1 to 3, in which seal means are provided between an end plate of the tray and the module, the end plate closing off an aperture in the module for receiving the tray.

4. Mounting means as claimed in any of claims 1 to 3, in which the strip is connected to the absorber at said opposite side thereof by means of fixing screws supported in the strip and along which the absorber may slide.

5. Mounting means as claimed in claim 4, in which certain areas of the edge portions of the absorber are deformed to provide lugs whose surfaces lie in a plane spaced from the plane of the absorber, the lug being provided with a through passage through which a screw may slide.

6. Mounting means substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings.

7. A pair of end plates for use in a module of the said type and adapted for fitment between a pair of castellations, said end plates each being provided with similar castellations whereby a module designed to accommodate a plurality of printed circuit boards and absorbers in a transverse orientation is convertible to accommodate a plurality of printed circuit boards and absorbers in a longitudinal orientation.

8. An end plate for use in a module of said type which has castellations on one end face, said end plate being adapted forfitment between castellations on the side faces of the module and having castellations corresponding with the castellations on said end face whereby printed circuit boards and absorbers are supportable by the castellations of the end face and plate longitudinally of the module.

9. An end plate for a module of said type or a module of said type when modified in accordance with claim 8, substantially as hereinbefore described with reference to Figure 3 of the accompanying drawings.

10. A module having a removable tray including electrical connectors into which the printed circuit boards or power pack of the module may be inserted to make electrical connection therewith, each lateral edge of the tray being resiliently urged against a supporting surface of the module by a plate arranged on the side thereof remote from said supporting surface, each plate being urged towards the tray by a plurality of resilient means.

11. A module as claimed in claim 10, including also resilient means at at least one end thereof.

12. A module as claimed in claim 10, in which the resilient means are coil springs accommodated in recesses in a member arranged beneath said plate.

13. A module as claimed in any one of claims 10 to 12, in which means are provided for fixing the tray in the module.

14. A module as claimed in any one of claims 10 to 13, in which seal means are provided between an end plate of the tray and the module, the end plate closing off an aperture in the module for receiving the tray.

15. A module substantially as hereinbefore described with reference to Figures 1 to 3 of the accompanying drawings.

16. Fixing means for holding a member in a module of said type, the fixing means comprising two pairs of co-operating slides arranged on either side of the member the abutting surfaces of the slides being inclined such that relative longitudinal movement of said members results in an increase in the transverse dimension of the pair of slides, which increase is utilised to fix said member against the end of the module or the face of a castellation.

17. Fixing means as claimed in claim 16, in which one of said slides is fixed relative to the module and the other is movable and screw means interconnecting said movable slide and the module provide said longitudinal movement.

18. Fixing means substantially as hereinbefore described with reference to the Figures 4 and 5 of the accompanying drawings.

19. Any novel subject matter or combination including novel subject matter herein disclosed, whether or not within the scope of or relating to the same invention as any of the preceding claims.

New claims or amendments to claims filed on 26th January 1984 Superseded claims ALL New or amended claims:

1. A module of said type having a removable tray including electrical connectors into which the printed circuit boards or power pack of the module may be inserted to make electrical connection therewith, each lateral edge of the tray being resiliently urged against a supporting surface of the module by a plate arranged on the side thereof remote from said supporting surface, each plate being urged towards the tray by a plurality of resilient means.

2. A module as claimed in claim 1, in which the resilient means are coil springs accommodated in recesses in a member arranged beneath said plate.

3. A module as claimed in claim 1 or claim 2, in which means are provided for fixing the tray in the module.