Micro-morphology of intermetallic compounds in rapid solidification Sn2.5Ag0.7Cu solder alloy and its effects on performance of solder joint

Rapid solidification Sn2.5Ag0.7Cu solder alloy ribbons were produced by single copper roller process with SP009A semi-automatic nonmetal series fabricate machine, and the micro-morphology and properties of intermetallic compound (IMC) were studied by JSM-5610LV scanning electronic microscope and energy spectrum analyzer. Through the analysis on the microstructure and shear fracture of the soldering joint, the influence mechanism of IMC on the toughness of soldering joint was studied. The results show that, in solder joint by using rapid solidification solder alloy, small size β-Sn tight arrangement at the interface can effectively inhibit the growth of IMC Cu6Sn5, and the IMC Cu6Sn5 and Ag3Sn in the supersaturated solid solution with small size and dispersive distribution massively precipitate as the second phase particle confounding with the primary phase during the solidification process to form fine eutectic structure in the soldering beam, and the toughness of soldering joint is improved.