METHOD OF TREATING COPPER CIRCUIT ON INNER LAYER PRINTED WIRING BOARD

摘要

PURPOSE:To treat a copper circuit on an inner layer printed wiring board to obtain a multilayer printed wiring board good in adhesion of the copper circuit, without causing haloing. CONSTITUTION:An inner layer printed wiring board is immersed in a water soln. of sodium chlorite composed of sodium chlorite 92-112g/liter and sodium hydroxide 35-45g/liter at a weight ratio of 2.0:1-3.2:1 to form a copper oxide film of 80-160mg/dm<2> on the copper circuit of this wiring board. Then, it is immersed in a week acidic water soln. to reduce the film thickness of the copper circuit of the wiring board to 3.2-33.6mg/dm<2> whereby the weight ratio of the film after the immersion in the week acidic water soln. to that after the immersion in the sodium chlorite water soln. ranges between 0.04 and 0.21 to 1.