リード線溶接における Sn ウィスカ発生メカニズムに関する研究

抄録

  This paper describes the mechanism of Sn whisker growth in the welding leads of aluminum electrolytic condenser. Such whiskers are crystalline, have lengths of several microns to several millimeters, and can occasionally result in device failure. The leads used for aluminum electrolytic condensers are composed of Sn- and Cu-plated Fe and Al wire by arc-stud welding. Observations have shown that the Sn whiskers grow in Al-Sn alloy regions at the welding point, where a three-dimension network of Sn exists as a result of rapid solidification from the melt in Al-Sn alloy. This network is microstructure of rapidly solidified from the melt. This one for the most part is occluded by Al, and has slightly opening to surface. It is considered that the driving force for whisker formation is the compressive stress that is present in the Sn network as a result of the different shrinkage rates of Al and Sn during solidification.