An influence of a surface finish of a Cu electrode on joint properties of a lead-free solder joint with Sn-3mass%Ag-0.5mass%Cu has been investigated. As the surface treatment method, Ni/Au electroplating, Au electroplating and organic solderability preservative (OSP) treatments were conducted to Cu electrodes. A heat exposure treatment was conducted at 150°C up to 500h in order to investigate the reliability of the solder joint under heat exposure conditions. Ball shear test was performed to examine joint strength. Microstructural observation was conducted to investigate growth kinetics of a reaction layer formed at a joint interface and microstructural revolution in the solder layer.