A new low-Ag lead free solder alloy and the reliability

This paper introduces a new low-Ag lead free solder alloy which possesses lower cost and higher performance. Also, the new alloy shows some satisfactory properties in solderability, HTS aging resistance, thermal cycling resistance, Shear strength, vibration shock aging and electromigration resistance. Experiments results indicated that both Ni and Bi elements in the low-Ag lead free solder alloy could enhance the solderability and aging resistance. Especially, addition of proper Bi element in the new solder alloy could improve the wettability between solder and pad, decrease the melting point of solder. Adding proper Ni elements in the new solder alloy could restrain the growth of IMC and refine grain size. According to the microstrcture morphology and fracture surface analysis, there is no honeycomb existence in the novel solder alloy after HTS aging and fine IMC grains exist in. Farther, fine grain size enhances the electromigration resistance, thermal shock resistance and shear strengthen.