| 摘要 |
PURPOSE:To prevent the stoppage of plating reaction and the abnormal deposition of plating, by dispersedly supplying an oxygen-containing gas in a fine bubble state into a plating bath at the time of plating the surface of a printed circuit board having fine circuit with Cu by an electroless plating method. CONSTITUTION:At the time of plating the surface of a printed circuit board having fine circuit with Cu into a circuit pattern by an electroless plating method, a printed circuit board 7 is immersed into an electroless copper plating bath 6 composed principally of copper ions, complexing agent for the copper ions, and reducing agent, by which Cu is subjected to electroless deposition onto the surface of the board 7. At this time, the plating bath 6 is supplied via an inlet 5 into a plating tank 1 and discharged via an outlet 4 to undergo circulation, and an O2-containing gas of >=10% O2 content is dispersed in a bubble state of <0.5mm bubble diameter through a gas-dispersing tube 3 provided to the bottom of the plating tank 1 via a gas-feed tube 2 at a rate of >=1% expressed in terms of 1atm. based on the volume of the plating bath. By this method, the plating bath is free from autolysis and its composition is always stable, and even a fine circuit can be accurately formed by Cu plating.
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