Effect of Different Ag Content on the Structural and Mechanical Properties of Sn15Bi Solder

 Yu Ding,1,*Email 

Fengjiang Wang,1

Yulin Li,1

Kaipeng Wang1 

1Provincial Key Laboratory of Advanced Welding Technology, Jiangsu University of Science and Technology, Zhenjiang 212003. China.

Abstract

Sn-Bi becomes one of the most potential solders due to its low melting point. In order to improve the function of SnBi solder, Ag is added to it. The microstructure of Sn15Bi solder consisted of primary β-Sn, Sn-Bi solid solution and Bi phase which precipitated along the grain boundary, while the bulk of Bi and many fine Ag3Sn phase appeared in SnBiAg solder matrix., The solders’ melting points were tested by DSC. With the Ag content increased, the melting point decreased. When the content reached 2wt.%, The melting point was 204.383℃, which was about 4% lower than the original solder; the wetting performance was tested by a wetting balancer, when the wetting temperature increased, the wettability got enhanced. Comparing the maximum wetting force and zero-crossing time ,  when the Ag content was 2wt.%, the wettability was the best; The analysis of the thickness and growth rate of the IMC showed, The thickness of the IMC increased with the increase of aging temperature and  time. However, when the Ag content exceeds 1wt.%, the growth rate slowed down in later stage of aging process, because Ag3Sn phase was formed above Cu6Sn5 gradually. Ag3Sn became a barrier, blocking the diffusion of Cu-Sn.

Effect of Different Ag Content on the Structural and Mechanical Properties of Sn15Bi Solder