METHOD FOR PRODUCING MULTI-LAYER PRINTED WIRING BOARDS HAVING BLIND VIAS

摘要

An alkaline refractory metal (2) which is insoluble in alkaline etching solutions, is electrodeposited on the surface of copper foil (1), then a thermosetting resin (3) is applied to the surface and semi-cured to obtain a coated copper foil. The coated copper foil is bonded to one or both faces of an inner layer board (5) having wirings (4) on one or both of its faces. Then, the copper foil (1) on a surface of this laminate is removed by alkaline etching, while selectively leaving the alkaline refractory metal layer (2). A laser beam is used to form via holes (6) in both the alkaline refractory metal layer and the thermosetting resin layer simultaneously. With the above method, via holes of the multi-layered printed wiring board can be easily formed using a laser, and adhesion between the outer wirings (8) made from the plated copper (7) and the insulating resin (3) is improved. IMAGE