Abstract:The web AuSn solders and AuSn/Ni joints were prepared by a rolling-annealing method and reflow process, respectively. The effects of the reflow time on the microstructure and the shear properties of the AuSn/Ni joints were investigated. The results show that the molten temperature and chemical composition of the AuSn solder prepared by rolling-annealing method are close to those of the common Au-20Sn eutectic alloy solder. The AuSn/Ni joint formed a fine lamellar eutectic ζ-(Au, Ni)5Sn+δ-(Au, Ni)Sn microstructure after reflow at 330 °C for 30 s. After reflowing for 60 s, a thin and flat layer of (Ni, Au)3Sn2 intermetallic compound (IMC) was formed with some needle-like (Ni,Au)3Sn2 intermetallics. Keeping increasing the reflow time, the (Ni, Au)3Sn2 IMC layer and intermetallics grew significantly. The shear strength of AuSn/Ni joints was improved with reflow time at the beginning, up to the best shear strength of 12.49 MPa at the point of 90 s, and then went down again with further increasing the reflow time.