Electromigration of Sn-Zn solders in contact with Cu

• Main Authors: Yen-Hsiang Fang, 方彥翔
• Other Authors: Kwang-Lung Lin
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/20790456183159644761

碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 92 === 　　The electro-migration behavior of Cu/Sn-Zn series solder/Cu under a current density of 650A/cm2 was investigated in this work. Meanwhile, the role of thermo-migration was investigated by the thermo-aging experiment. The Sn-Zn series solders investigated include Sn-8.6Zn, Sn-4.5Zn, Sn-2.5Zn and Sn. 　　The SEM and EPMA results obtained showed that, different compounds were formed on decreasing the zinc content of the solder. For high Zn content solder, Sn-8.6Zn, a continuous layer of Cu5Zn8 was observed and the copper layer of cathode side were consumed greatly after a current stressing for 456 hours. In the case of Sn-4.5Zn, Cu5Zn8 was further formed in the matrix near the cathode side. However, for the Sn-2.5Zn solder, Cu5Zn8 was found in the matrix and Cu6Sn5 was found at the interface. For pure Sn, Cu6Sn5 and Cu3Sn were found in the matrix and at the interface after a current stressing of 216 hours, respectively. Under the thermo-aging test, Cu5Zn8 was just found at the interface of Sn-8.6Zn and Sn-4.5Zn. 　　Under the thermo-aging test, the copper diffused along the grain boundary to react with zinc. It can be observed that under the action of the electric field, the atoms diffused to react with zinc through the grain.