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Effects of bismuth on growth of intermetallic compounds in Sn-Ag-Cu Pb-free solder joints

Authors :
Xun-qing Shi
Guo-yuan Li
Source :
Transactions of Nonferrous Metals Society of China. 16:s739-s743
Publication Year :
2006
Publisher :
Elsevier BV, 2006.

Abstract

The effects of Bi addition on the growth of intermetallic compound (IMC) formation in Sn-3.8Ag-0.7Cu solder joints were investigated. The test samples were prepared by conventional surface mounting technology. To investigate the element diffusion and the growth kinetics of intermetallics formation in solder joint, isothermal aging test was performed at temperatures of 100, 150, and 190 °C, respectively. The optical microscope (OM) and scanning electron microscope (SEM) were used to observe microstructure evolution of solder joint and to estimate the thickness and the grain size of the intermetallic layers. The IMC phases were identified by energy dispersive X-ray (EDX) and X-ray diffractometer (XRD). The results clearly show that adding about 1.0% Bi in Sn-Ag-Cu solder alloy system can refine the grain size of the IMC and inhibit the excessive IMC growth in solder joints, and therefore improve the reliability of the Pb-free solder joints. Through observation of the microstructural evolution of the solder joints, the mechanism of inhibition of IMC growth due to Bi addition was proposed.

Details

ISSN :
10036326
Volume :
16
Database :
OpenAIRE
Journal :
Transactions of Nonferrous Metals Society of China
Accession number :
edsair.doi...........8dd975e2b897246aa9416baeb22995f7