The Investigation of Reactions between Liquid Phase Sn-Ag-Bi-In Lead-Free Solder and Copper Substrate

• Main Authors: Ming-Hsun Chen, 陳銘訓
• Other Authors: Tseung-Yuen Tsen
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/t9vg7y

碩士 === 國立臺北科技大學 === 材料科學與工程研究所 === 96 === This thesis investigated the phenomenon of the reactions between Sn-Ag-Bi-In lead-free solders and Cu substrates. Two lead-free solders, 84Sn3Ag3Bi10In and 89Sn3Ag3Bi5In, were used to investigate the liquid-solid state reactions. The addition of indium and bismuth decreases the melting point of 84Sn3Ag3Bi10In and 89Sn3Ag3Bi5In to 203 and 212℃, respectively. Two layers of intermetallic compounds, Cu6Sn5 and Cu3Sn, formed between the solders and the substrates. The results revealed that In atoms did not dissolve in the intermetallic compounds to replace Sn atoms. Besides, some Cu6Sn5 spalled and many fine Sn-Ag-In particles dispersed in the solders. The growth rate constant and the growth exponent could be deduced from the calculation of the thickness of the intermetallic compounds. The fitted results revealed that the growth exponent n equals to 1/3 and suggested a ripening controlled process during reflow. The apparent activation energy could be calculated by Arrhenius equation and that of the growth of Cu6Sn5 and Cu3Sn was 48.3 kJ/mol and 55.1 kJ/mol, respectively. The composition of the intermetallic compounds that dispersed in the solders was analyzed by electron probe microanalysis. The results suggested that the fine particles mainly areζphase that were composed of Sn, Ag, and In atoms with large miscibility range. The ζ phase is the solid solution of ζ (Ag4Sn) and ζ (Ag3In), which both have the crystal structure of HCP. Sn and In dissolved more in the dispersed particles with increasing reflow time. No In signal could be detected in the intermetallic compounds at the interfaces during reflow.