METHOD OF MANUFACTURING WIRING BOARD

摘要

A wiring board is manufactured using a method in which holes are opened in a copper layer by laser without excessive load. An upper copper layer (5) undergoes a surface treatment, such as roughing and plating, so that the effective absorption index of the upper copper layer (5) can be greater than that of copper itself. Laser machining is carried out without opening a window in the treated upper copper layer (5). The laser intensity need not be extremely high, as compared to the case where only an upper insulating layer (4) is processed. A major part of the laser energy irradiating the upper copper layer (5) is used to process the upper copper layer (5) and the upper insulating layer (4). The processing ends at a lower copper layer (3) that is not surface-treated, with the result that via holes are formed.