| 摘要 |
PROBLEM TO BE SOLVED: To obtain a high-density printed wiring board, where a well-shaped pattern which is formed by the use of very fine wire that has proper adhesion to a copper foil on a thin copper foil plated copper plated board. SOLUTION: An ultrathin copper foil (b) which is provided with a through- hole and/or a blind via hole and whose outermost copper foil is 5μm or below in thickness is used; an electroless copper plating (c) of thickness 0.1 to 3μm is deposited on the thin copper foil (b). Then an electroplating copper layer (d) of thickness 0.5 to 3μm is formed thereon; a plating resist layer (f) is provided; then an electroplating copper layer (d) 6 to 30μm in thickness is deposited thereon, the plating resist layer (f) is separated, and the thin electroplating copper layer (d); and the electroless copper plating layer (c), and the ultra thin copper foil layer (b) are removed by dissolution, so that a pattern satisfying a formula, line/space = 40/40μm or below, can be obtained. Therefore, a undercutting of copper pattern hardly occurs, and a high-density printed wiring board equipped with a wiring pattern superior in adhesion to a copper foil can be obtained.
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