GB651780A - Improvements in or relating to electrical connections and circuits and their manufacture - Google Patents

Abstract

651,780. Printed circuits. STANDARD TELEPHONES & CABLES, Ltd. June 25, 1947, No. 16779. [Class 36] An electrical circuit comprises a plurality of superimposed insulating sheets which are bonded together by heat and pressure to form a laminated unit, at least one of the sheets having conductive paths formed from metallic paste printed or otherwise deposited thereon. Fig. 1 illustrates a circuit, the conductors of which are deposited on sheets of insulation such as resin-impregnated paper, in the manner shown in Fig. 2, like references indicating the same points of the circuit. The top sheet carries no conductors, but is provided with holes for giving access to the conductor terminals on the lower sheets. The second and third sheets, which are also provided with holes where necessary, have conductive lines formed thereon, the circuit terminations L, M, S, &c. being brought to the edges of the sheets and enlarged as at L<SP>1</SP>, M<SP>1</SP>, S<SP>1</SP>, &c. The fourth sheet carries the valve heater leads which are formed of metal tapes threaded through slits in the sheet. The bottom sheet is left plain. The sheets are then stacked in the order shown and moulded in a heated press into a laminated unit. The heat and pressure also improves the conductivity of the deposited conductors. The unit is then provided with terminal tags at the exposed circuit terminations on the edges of the unit, and other components are positioned and soldered to the conductor terminals G, H, K, &c. to which access may be had through the apertures in the insulating sheets. A valve holder -is then inserted in the central aperture. More complicated circuits such as radio receivers may be made by this method, and the units may be bent or folded into any desired configuration. Connection may be made between superposed. points on different sheets by removing the insulation between the conductors at such points and applying solder around the holes so formed. After moulding, the conductors at these points can be soldered together. The parts of the circuit at which soldered connections are to be made preferably have a layer of metal such as copper deposited electrolytically thereon. Insulation may be increased by inserting insulating sheets between the conductor carrying sheets. Resistances inductances and condensers may be made in the same manner as the conductors if desired, using suitable conductive or resistance pastes. Specifications 4681/03, [Class 36], 569,388, [Group II], 624,149 and 639,591, [Group XXXV], are referred to.