摘要 |
A flexible wiring board are formed by growing metal bumps using a mask film patterned by photolithography. Fine openings can be formed with good precision, therefore, fine metal bumps can be formed with good precision because laser beam is not used to form opening in a polyimide film. After metal bumps have been formed, the mask film is removed and a liquid resin material is applied and dried to form a coating, which is then cured into a resin film. The coating can be etched at surface portions during coating stage to exposed the tops of metal bumps. |