| 摘要 |
PROBLEM TO BE SOLVED: To enable fine interlayer connection holes to be bored in a metal foil by a laser beam and a fine wiring to be formed and enhanced in adhesion to a plating copper, by a method wherein a semi-cured insulating adhesive layer is provided onto the roughened surface of the metal foil whose roughness is prescribed. SOLUTION: A semi-cured insulating adhesive layer (thickness: 25μm to 100μm) 5 is provided onto the surface of a metal foil (copper foil) 1 whose roughness is represented by that the number of ridges amounts to 120 or above per reference length of 25 mm. In this case, the semic-cured insulating adhesive material layer formed on the roughened surface of the metal foil 1 contains insulating short fiber material whose diameter is 0.1 to 3μm and average length is 5 to 50 times as long as its diameter. By this setup, interlayer insulating holes smaller than 0.15 mm in diameter can be bored in the semi-cured insulating adhesive layer, a fine wiring can be formed on the insulating adhesive layer, and the insulating adhesive layer can be enhanced in adhesion to a plating copper. |
