Study on interface of Sn-Ag-Zn lead free solder with low silver content

Abstract

Abstract The interface reaction between Sn-1Ag-1Zn low silver alloy solder and different substrates was studied. After aging at 200 ℃, a double-layer IMC structure is formed at the interface. Cu5Zn8 and Ag3Sn are formed from Cu substrate to solder in turn. The morphology of interface Cu5Zn8 has no change with aging. After aging for 100 h, the thickness of Ag3Sn is only about 4 μ m, and the IMC of bilayer structure blocks and suppresses each other. After Sn-1Ag-1Zn solder is welded to Cu substrate with Ni barrier layer, Ni3Sn4 layer is formed on the surface, and its thickness increases slowly with aging time at 200 ℃. After aging for 1000 h, the thickness of Ni3Sn4 layer is only about 1 μ m, and the morphology is smooth. There is no aggregation of other alloying elements near the interface and IMC which destroys the reliability of the interface is formed. The Ni barrier layer has a good barrier effect.