| 摘要 |
PROBLEM TO BE SOLVED: To provide a lead frame of a three-layer structure capable of being easily formed by electric plating without necessity of a complicated step such as a vapor depositing or the like and enhancing reliability with a low cost. SOLUTION: The lead frame comprises an etching stop layer made of a nickel metal layer such as, for example, a nickel-phosphorus alloy layer having a thickness of 0.04 to 70μm formed between an outer lead constituted of copper or copper alloy layers each having a thickness of, for example, 35 to 300μm and an inner lead constituted of a copper layer having a thickness of, for example, 0.2 to 30μm thinner than that of the outer lead. The frame has three-layer structure having the etching stop layer made of the nickel metal as an intermediate layer, and the nickel metal has strong etching resistance against etching of the copper or copper alloy. Thus, the structure can effectively prevent an influence of selectively etching the outer lead to the thin copper layer for forming the inner lead. Hence, since it is adapted to formation of fine leads, the fine leads can be formed.
|
