GB932210A - Improvements in and relating to printed circuits - Google Patents

Abstract

932,210. Printed circuits. DIELEKTRA A.G. Dec. 2, 1960 [Dec. 12, 1959], No. 41486/60. Class 37. The individual conductors of a printed circuit board are formed from metal foil clad to both sides of an insulating material and are separated from each other on the surface by etched grooves and at the edges of the board by notches; the metal foil on each side of the board being conductively connected by metallizing the cut edges of the insulating material between the two sides. A panel is punched from a sheet of insulating material 1 clad on both sides with metal foil and in the same process holes and apertures are punched in the panel where desired ; the insulating material being of any suitable material examples being given in the Specification. The cut edges of the panel are sensitized with a graphite or silver-powder layer 3, and then stacked in a copper electroplating bath where the cut edges are plated with a layer 4 of copper. The panels are then printed in negative form by a photographic method with the desired wiring pattern so that only the eventual separations between the conductors are covered with a plating resist; and are again immersed in a plating bath so that the parts not covered with the resist are electroplated with a different metal 7, Fig. 2, to that of the foils and the metallized cut edges; the different metal being preferably silver or nickel. After washing and drying the panels the resist is removed and the panels etched to form separations 6 in any known way. The board is completed by punching out notches 5 in the edges of the panel. If a different metal is used for metallizing the cut faces to that of the metal foil the panel may be photo-printed in positive form and also after metallizing the cut faces the notches for separation of the conductors on the edges may be cut out and only then is the printing and etching or printing in negative form, plating with the other metal and etching carried out. Figs. 5 and 6 (not shown) show a circular printed circuit with radially extending conductors. If a similar pattern is used on both sides of the boards the conductors may be closed in themselves and not interconnected. It is also possible not to have annularly closed conductors but to have a closed circuit which transcribes the panel as many times as there are radial conductors on the surface. Specification 758,688 is referred to.