Method of making a die for stamping out circuit boards

Abstract

Abstract A PROCESS OF MAKING AN IMPROVED DIE FOR STAMPING OUT FROM A FOIL SHEET CIRCUIT BOARD ELEMENTS ONTO A SUBSTRATE. THE PARTICULAR DIE CONFIGURATION MADE BY THIS PROCESS IS A "MODIFIED FLAT FACE DIE," WHEREIN THE MIDDLE PORTION OF AN INDIVIDUAL DIE ELEMENT IS MODERATELY RECESSED. THE PROCESS IS AS FOLLOWS: (A) FIRST A CONVENTIONAL FLAT FACE DIE, COMPRISING FLAT FACE DIE ELEMENTS WITH INTERVENING RECESS AREAS, IS FORMED; (B) THE RECESS AREAS ARE FILLED WITH AN ACID-RESISTING EPOXY, AND A PHOTO-RESIST IS APPLIED OVER THE EPOXY IN A MANNER TO OVERLAP THE OUTER EDGE PORTIONS OF THE DIE ELEMENTS SO THAT THE MIDDLE PORTION OF EACH DIE ELEMENT IS EXPOSED; (C) THE DIE IS PLACED IN AN ETCHING SOLUTION TO FORM A MODERATE RECESS IN THE MIDDLE PORTION OF EACH DIE ELEMENT, WITH SHOULDERS BEING FORMED ALONG THE OUTER PORTIONS OF EACH DIE ELEMENT; (D) THEN THE ACID-RESIST MATERIAL IS REMOVED, AND THE DIE SURFACE IS AGAIN ETCHED FOR A SHORT PERIOD OF TIME; (E) THE EPOXY FILLER IS REMOVED. IN A FIRST EMBODIMENT, THE DIE IS ETCHED THE SECOND TIME ONLY ENOUGH TO ROUND OFF THE INNER EDGE OF EACH SHOULDER OF THE DIE ELEMENT TO LEAVE FLAT FACE SHOULDER PORTIONS ON THE DIE ELEMENT. IN A SECOND EMBODIMENT, THE INNER PORTION OF EACH OF THE TWO SHOULDERS IS ETCHED AWAY TO LEAVE A KNIFE EDGE AT THE OUTER EDGES OF EACH DIE ELEMENT. TO PROVIDE THE ANTI-RESIST COATING WHICH OVERLAPS THE OUTER PORTIONS OF THE DIE ELEMENTS AS DESCRIBED IN STEP (B) ABOVE, AN ACCURATE PHOTOGRAPHIC REPRODUCTION IS MADE BY PLACING THE FLAT FACED DIE IN A DEVELOPING SOLUTION AND PRESSING A FULLY EXPOSED FILM AGAINST THE DIE. AFTER THE FILM PORTIONS EXPOSED TO THE DEVELOPING SOLUTION ARE DEVELOPED, THE FILM IS PLACED IN A FIX SOLUTION TO MAKE A PHOTOGRAPHIC REPRODUCTION. THEN A POSITIVE IS MADE FROM THIS REPRODUCTION AND THIS POSITIVE IS PLACED AGAINST AN UNEXPOSED FILM AND LIGHT IS DIRECTED THROUGH THE POSITIVE ONTO THE FILM. SIMULTANEOUSLY THE REPRODUCTION IS ROTATED LATERALLY TO A VERY MODERATE EXTENT WHILE MAINTAINING THE SAME ORIENTATION OF THE REPRODUCTION, SO THAT THE TRANSPARENT PORTIONS OF THE REPRODUCTION (CORRESPONDING TO THE RECESS AREAS OF THE DIE) ARE WIDENED MODERATELY TO MAKE A MODIFIED REPRODUCTION. THEN AN ACID-RESIST COATING CORRESPONDING TO THE TRANSPARENT AREAS IN THIS MODIFIED PATTERN IS PLACED ON THE DIE FACE SO AS TO FORM THE PHOTO-RESIST COATING USED IN STEP (B) ABOVE.

Inventors

• 👤 W Weglin

Bibliographic Details