| 摘要 |
PROBLEM TO BE SOLVED: To obtain a sound board nonsusceptive to the effect of a pin hole by coating the board, including the part of an insulator exposed through the pin hole, with copper through electroless plating while covering the exposed part completely thereby making the entire surface of the board highly conductive. SOLUTION: An insulator film, e.g. a polyimide film, is coated on one side or both sides thereof with copper by 0.05-0.5μm as an underlying metal layer by dry plating, e.g. vacuum deposition, to produce a board. The part of the insulator film on the board exposed through the pin hole by dry plating is then rendered hydrophilic using an inorganic alkaline solution of potassium hydroxide or an organic alkaline solution of hydrazine, for example, and the board is subjected to a catalyst imparting processing required for electroless plating over the entire surface thereof and a catalyst is imparted to the surface of the insulator film and the surface of the underlying metal copper layer. Subsequently, the surface of the substrate is coated with copper through electroless plating in order to make the entire surface of the board highly conductive.
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