MANUFACTURE OF MULTILAYER WIRING BOARD

PROBLEM TO BE SOLVED: To reduce the dimensional change in processing stage after multilayering by heat-treating a multilayer wiring board where an inner-layer circuit board and a prepreg are stacked into a multilayer, within the specified temperature range for stacking before circuit processing. SOLUTION: A laminate where both sides of glass base material epoxy resin are covered with copper is processed to make a circuit by etched foil method, and further oxidation treatment is applied to the surface of the copper foil 3 of the circuit. Copper foils are arranged through one sheet each of glass cloth base material epoxy resin prepreg 2 above and below this manufactured inner-layer circuit board 1. This combination constituent material is heated and pressurized at 2.94 MPa and 170 deg.C for 90 minutes in decompressed atmosphere, and then it is cooled for 30 minutes, with this pressure on, so as to make a four-layer board. Heat treatment at 160-180 deg.C for 60 minutes is applied to this four-layer board with a hot blast circulation system of drier. In the range of ±10 deg.C of this laminate formation temperature, the dimensional property can be improved most within the treatment temperature range fit for resin. Accordingly, dimensional change and dispersion are small, and further there is no discoloration of the substrate.