| 摘要 |
PURPOSE:To prevent any change (such as oxidation) in surface condition of solder coat applied in advance to an outer portion of a lead in assembly process for semiconductor device. CONSTITUTION:A heat-resistive protection layer 20 made of polyurethane resin is formed on a solder coat 10 adhered to an outer portion 9b of a lead projected out to the external side of a resin sealing package 14. In mounting of a semiconductor device 70 to a printed circuit board by soldering, a heat resisting protection layer 20 is removed by a chemical such as hydrochloric acid or sulfuric acid. By doing this, the solder coat 10 is covered with a heat-resistant protective layer 20, so that no oxidation nor discoloring occurs even though the lead frame is heated. The solder coat 10 is not oxidized and thus soldering is performed effectively during mounting. Since the solder coat 10 can be adhered in advance, a wet type solder adhesion treatment after the formation of resin sealing package formation can be omitted. |
