Thin multi-layer circuit board and process for fabricating the same

Abstract

A process for fabricating thin multi-layer circuit boards which allow the electrical conduction of remodeling pads to be easily cut do not use etching for gold, avoid the lift-off method for forming a thin chromium film on the wiring pattern layer, allow a defective wiring pattern layer to be removed, and which uses uniform heating of the substrate, from the back side thereof, at the time of pre-baking. A barrier metal (60) is excluded from a portion where the electrical conduction of a remodeling pad (62b) is to be cut (FIGS. 1 to 16). Alternatively, gold-plating resist is formed in order to avoid the etching for gold (FIGS. 17 to 19). Alternatively, a thin chromium film is formed in advance by etching on the wiring pattern layer (FIGS. 27 to 33). Alternatively, a metallic barrier film (122) is formed on each of the wiring pattern layers so that the wiring pattern layer can be removed without affecting other wiring pattern layers (FIGS. 36 to 42). Alternatively, the substrate is disposed over a heat-accumulating block (138) adjacent thereto so that it is uniformly heated from the back side thereof during the pre-baking.