Methods for producing printed circuits

Claim 1

THE METHOD OF PRODUCING A PRINTED CIRCUIT WHICH INCLUDES THE STEPS OF: (A) PRINTING A REPRESENTATION OF A CIRCUIT TO BE PRODUCED UPON THE ETCHABLE METALLIC SURFACE OF A LAMINATE IN A MEDIUM ABSORBENT TO A THERMOPLASTIC POWDER FORMING A SOLDERING FLUX RESIST AFTER FIRING BY MEANS OF AN OFFSET PRINTING PLATE CARRYING SAID REPRESENTATION, (B) DUSTING THE PRINTED SURFACE WITH A ROSIN-BASED THERMOPLASTIC POWDER FORMING, AFTER FIRING, A RESIST WHICH WILL ALSO FUNCTION AS A SOLDERING FLUX, (C) REMOVING THE POWDER NOT ADHERING TO THE ABSORBENT MEDIUM, (D) HEAT FUSING THE ADHERENT POWDER TO FORM A SOLDERING RESIST PATTERN, (E) HOT ETCHING THE EXPOSED METALLIC SURFACE WITH AN ETCHANT HAVING A SUFFICIENT TEMPERATURE TO CAUSE THE EXPOSED METALLIC SURFACE TO BE REMOVED AND TO SOFTEN THE RESIST SUCH THAT IT WILL EXTRUDE AROUND THE CIRCUIT TO BE PRODUCED, THUS PREVENTING UNDERCUTTING OF THE REMAINING METALLIC SURFACE OF THE CIRCUIT, AND (F) SOLDERING COMPONENTS TO SAID REMAINING METAL WHILE SAID RESIST IS STILL IN PLACE.