摘要 |
PURPOSE:To make inner leads finer without hindrance and to intensify the adhesibility of the inner leads to an etching stopper in a lead frame forming method in which a lead frame is formed by using a lead frame forming material having a three-layer structure composed of a thick Cu layer for forming outer leads and thin Cu layer for forming inner leads respectively formed on both surfaces of an Al layer which becomes the etching stopper. CONSTITUTION:A lead frame material comprises a copper base 1, which is coated by physical vapor deposition with an Al layer 2 on one side and a Cu layer 3 on the other side. |