Method and apparatus for making cylindrical printed circuits

Claim 1

THE METHOD OF MAKING A TRANSPARENT PHOTOGRAPHIC IMAGE CARRIER FOR USE IN FASHIONING CYLINDRICAL PRINTEDCIRCUIT ELEMENTS SUCH AS INDUCTANCE COILS, COMPRISING THE STEPS OF DEPOSITING A THIN COATING OF TRANSPARENT PLASTIC ON A CYLINDRICAL MANDREL, METALIZING THE SURFACE OF SAID PLASTIC COATING, DEPOSITING A LAYER OF PHOTO-RESIST COMPOUND OVER SAID METALIZED SURFACE, EXPOSING SAID LAYER TO LIGHT THROUGH AN IMAGE-CARRYING FILM TO PRODUCE THEREIN A LATENT IMAGE REPRESENTING SAID PRINTED-CIRCUIT ELEMENT, DEVELOPING THE LATENT IMAGE IN SAID PHOTO-RESIST LAYER, ETCHING SAID METALIZED SURFACE TO REMOVE THE SAME IN ALL AREAS THEREOF NOT COVERED BY SAID DEVELOPED IMAGE, COATING SAID ETCHED METALIZED SURFACE WITH A THIN LAYER OF TRANSPARENT PLASTIC, THUS SANDWICHING SAID ETCHED SURFACE BETWEEN SAID FIRST AND SECOND LAYERS OF PLASTIC, MOUNTING SAID COATED MANDREL WITHIN A RIGID TRANSPARENT PROTECTIVE COVER WHOLLY ENCLOSING SAID ETCHED METALIZED SURFACE AND CIRCUMFERENTIALLY ABUTTING SAID SECOND PLASTIC LAYER IN TWO SPACED ZONES, SEALING SAID COVER CIRCUMFERENTIALLY TO SAID SECOND PLASTIC LAYER IN BOTH OF SAID ZONES, AND DISSOLVING AWAY SAID MANDREL.