| 摘要 |
PROBLEM TO BE SOLVED: To optimize soldering by selectively covering an area of lead frame which is to be soldered by gold-plating for visual discrimination of the area. SOLUTION: At solder joint, a layer 106 which is selectively gold-plated by thickness 2-5 nm is provided to prevent surface oxidation of an electric plating nickel layer 104 under it. A mask which covers a part of an electric plating precious metal layer 105 allows gold deposition to start with a limit 106a, so a gold is spot-plated in such area as soldering capability is required. With a thickness in this range, a gold has an assured capability for soldering, while an area plated with gold is visually discriminated from an adjoining palladium or nickel surface where no gold is deposited, which is suitable for automated visual inspection at control of manufacturing process, contributing to assured products. |
