Patent GB-1217621-A (GB)
Title: Circuit assembly
Inventor: CUZNER DAVID EVERARD
IPC: H01L23/467
Filed: 1968-02-13
Abstract: 1,217,621. Circuit assemblies. INTERNATIONAL BUSINESS MACHINES CORP. 13 Feb., 1968, No. 7012/68. Heading H1R. In a circuit assembly in which a plurality of printed circuit cards are mounted in a spacedapart relationship in a supporting structure, the circuit cards being each provided with an aperture through which an expandable tube extends to supply cooling air to the cards, the tube is removable from the assembly. The assembly comprises a central air distribution box of square cross-section, Fig. 1 (not shown), and four sub-assemblies projecting one from each face of the central distribution box. Each subassembly comprises an air distribution tube 11, Fig. 3, communicating with the air box and formed of four printed circuit boards 32 provided with rows of apertures for allowing the passage of air, Fig. 9 (not shown). The tube 11 extends through aligned apertures of a plurality of apertured printed circuit cards 12 to 17, cards 12 to 15 carrying a plurality of micromodules and providing the interconnection therebetween. Printed circuit cards 16, 17 do not carry modules but are connected by tape cables and connectors 18, 19 to interconnecting cards in other adjacent sub-assemblies. Each printed circuit board 32 of the tube 11 is provided with a backing plate 80 to which an expanding force is applied by an expanding device which comprises two rubber bushes 90 free to move along actuating bolt 84 in each of which is embedded the ends of four equally spaced radially extending struts 91 push fitted into rubber-lined sockets 92 in the backing plates 80. In an unloaded position the struts 91 are held at an angle to the radial plane so that the tube 11 can be inserted through the cards 12 to 17. After insertion the boards 32 of the tube 11 are expanded by screwing the actuating bolt 84 into the nut 85 in the central air box so that the boards 32 are pushed outwardly into contact with connector 71 which forms one side of a rectangular connector assembly, one of which is located on each face of printed circuit cards 12 to 17. The sub-assemblies are each releasably supported by a supporting structure comprising four power buses 62 which are bolted at one end to the central box. Stubs 60 at each corner of a card 12 to 17 are clamped to respective ones of the four busbars 62 by suitable clamps, which are constructed so that when released they can be withdrawn along the bus-bar to permit withdrawal and reinsertion of any one of the cards without disturbing the others. The air distribution tube is withdrawn before the withdrawal of a card. Cooling air is blown from the central air box down the tube 11 through the apertures in the backing plates 80 and printed circuit boards 32 and in the spaces between baffles 38 mounted adjacent printed circuit cards 12 to 17 carrying modules 22 which include integrated circuits mounted on a substrate and encapsulated in a metal can in thermal contact with the integrated circuit. Metal extension pins of square crosssection project from the upper surface of the can and improve the exchange of heat between the module and cooling air. Reference has been directed by the Comptroller to Specifications 1,128,939 and 1,128,940.