| 摘要 |
PURPOSE:To improve the reliability of electric conduction of a through hole by a method wherein an electroplated copper layer is formed on a land and the inner wall surface of a through hole, by utilizing selective etching property of copper and nickel. CONSTITUTION:A chemical nickel plated layer 7 as a substratum is formed on the whole part containing the inner wall of a through hole 4 and a land 6. By using said substratum 7, a dense electroplated copper layer 9 is formed so as to cover the inner wall surface of the through hole 4 and a land 6. As a result, the formed copper layer 9 possesses density, and maintains almost uniform quality. The formed electroplated copper layer 9 is further coated with a nickel plated layer 7'. In this state, the layer 9 is etched and eliminated together with the chemical nickel layer 7 covering a circuit part, so that the electroplated copper layer 9 is not damaged. Thereby the reliability of electric conduction of through hole is improved. |
