THIN FILM WIRING SHEET, MULTILAYER WIRING BOARD AND THEIR PRODUCTION

• Main Authors: SHOJI FUSAJI, TOGAWA HIDEO
• Format: Patent
• Language: English
• Published: 25.02.1997
• Edition: 6
• Subjects: ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; ADHESIVES; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; CHEMISTRY; DYES; ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS; METALLURGY; MISCELLANEOUS APPLICATIONS OF MATERIALS; MISCELLANEOUS COMPOSITIONS; NATURAL RESINS; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; PAINTS; POLISHES; PRINTED CIRCUITS; USE OF MATERIALS AS ADHESIVES

PROBLEM TO BE SOLVED: To suppress the curling by providing the wiring layers on the opposite sides and arranging an adhesive layer of polymer material and a low thermal expansion layer of polymer material symmetrically in the vertical direction. SOLUTION: A low thermal expansion polyimide precursor solution is applied onto the surface of a copper foil 102 and heated. An adhesive polyimide precursor solution is then applied thereon and heated. It is then imidized to obtain a first insulation layer 11 comprising a first low thermal expansion polyimide layer 103 and a first adhesive polyimide layer 104. Subsequently, a through hole 105 is filled with copper by electrolytic copper plating thus forming a first via wiring 115. A copper plating layer 106 is then etched to form a first wiring pattern 107. Similarly, a second insulation layer 12 is formed on a second pattern 109 and a via wiring 116 is obtained by electroless plating while a third wiring pattern 134 is obtained by etching. With such a method, a high density high performance multilayer wiring board can be produced at high yield without taking many days.