METHOD FOR PRODUCING VIAS IN THE MANUFACTURE OF PRINTED CIRCUIT BOARDS

摘要

IN A PROCESS PRODUCING A MULTI-LAYER PRINTED WIRING BOARD, AN INNER CORE HAVING AT LEAST ONE WIRING PATTERN (3) ON ITS SURFACE AND AN OUTER LAYER OF COPPER FOIL (1) ARE LAMINATED WITH AN ORGANIC INSULATING LAYER (2) INTERPOSED THEREBETWEEN, A VIA HOLE (5) IS FORMED USING A LASER BEAM, AND THE OUTER COPPER FOIL (1) AND THE INNER WIRING PATTERNS (3) ARE ELECTRICALLY CONNECTED TO EACH OTHER BY DEPOSITING COPPER. THE PROCESS IS CHARACTERIZED IN THAT THE OUTER LAYER OF COPPER FOIL (1) HAS A THICKNESS OF NO MORE THAN 1/4.5 OF THE THICKNESS OF THE INNER WIRING PATTERN (3), BUT WILL NOT EXCEED 7ΜM, PREFERABLY 4ΜM. THE HOLE (5) IS FORMED IN BOTH THE COPPER FOIL (1) AND THE INSULATING LAYER (2) SIMULTANEOUSLY BY IRRADIATING WITH A LASER BEAM ON THE OUTER LAYER OF COPPER FOIL (1).FIGURE 1