| 摘要 |
PURPOSE: To obtain a circuit board at a low cost by directly forming a polyimide film on a copper pattern. CONSTITUTION: A copper plating pattern 2 on a board is subjected to spin- coating with non-photosensitive polyimide precursor of a viscosity of 100 CPS, at a speed of rotation of 100 RPM, for 30 seconds, and curing is performed at 390 deg.C. A non-photosensitive polyimide film 1 formed in this manner is subjected to spin-coating with photosensitive polyimide precursor of a viscosity of 350 CPS, at a speed of rotation of 700 RPM, for 30 seconds, and prebaking is performed at 80 deg.C, for 1 hour. A photosensitive polyimide precursor film is exposed to UV rays and developed. Thus viaholes 3 are formed. After the viaholes are formed, the surface of photosensitive polyimide 5 formed by curing at 390 deg.C is subjected to dry etching. Thereby the nonphotosensitive polyimide film 1 left in the bottom part of the viaholes 3 is eliminated, and viaholes capable of electric continuity with the copper plating pattern of the upper layer are formed. |
