Interfacial reaction between Sn-1Ag-0.5Cu(-Co) solder and Cu substrate with Au/Ni surface finish during reflow reaction

Abstract

In order to clarify the effect of the addition of Co to SAC105 solder, the reaction between solder and Au/Ni surface finish has been investigated, and the joint strength was also evaluated by a ball shear test. After soldering, the interfacial reaction layer in the SAC105 Co solder contained Co, and the chemical composition of intermetallic compounds (IMCs) were identified as (Cu,Ni,Co)(6)Sn(5) and (Ni,Cu,Co)(3)Sn(4) by energy-dispersive X-ray spectrometer (EDX), which significantly differed from that of SAC105 solder. After multiple reflows, the formation rate of the (Cu,Ni,Co)(6)Sn(5) IMC for the Co-added solder slow compared with that of (Cu,Ni)(6)Sn(5) IMC for SAC105 solder. Experimental results clearly indicate that adding small amounts (0.05 wt.%) of Co to SAC105 solder strongly affected the formation of the IMC at the interface. Furthermore, ball shear test results demonstrate that the SAC105 and SAC105 Co solder joints have good joint reliability. (C) 2008 Elsevier B.V. All rights reserved.