| 摘要 |
PURPOSE:To improve solderability of a semiconductor device by a method wherein an Sn or Sn alloy film is convered up to the specified thickness on the surface of a projecting lead, and an organic film to melt or to dissolve at the practical soldering temperature is formed thereon to the specified thickness. CONSTITUTION:At a semiconductor device provided with leads projecting outside from a sealed body, an Sn or Sn alloy film is covered to 0.1-3mum thickness on the surfaces of the projecting leads. An organic film to melt or to dissolve at the practical soldering temperature is formed thereon to 0.1-50mum thickness. The reason why the covering thickness of the Sn or Sn alloy film is limited to 0.1-3mum, it is because corrosion resistance and solderability are also reduced in proportion to reduction of covering thickness. When covering thickness is less than 0.1mum, sufficient solderability can not obtained, and when thickness exceeds 3mum, the above-mentioned effect attained owing to formation in a thin film is lost. Thickness of the organic film is made to 0.1-50mum, desirably made to 0.5-20mum, and when thickness is less than the lower limit, protective action is insufficient, and solderability is deteriorated. Heat shock, solder-bridge, etd. according to formation in small type, formation in high density can be dissolved.
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