Wetting properties, recrystallization phenomena and interfacial reactions between laser treated Cu substrate and SAC305 solder

Effect of laser treatment has been studied on the wetting ability of Cu substrate during soldering with SAC305 solder paste. The contact angle of molten solder drops on Cu substrate changes when the substrates treated with different Nd:YAG laser powers. The correlations between the extraordinary change of wetting angle and the surface interaction between the melt pool of solder alloy and Cu plates are studied. A texture formation was found in the laser treated Cu substrate, which supports the diffusion of the Sn atoms. The thickness of Cu3Sn interface layer is increasing with increasing laser power helping the formation of Cu6Sn5 phase, and resulting a better metallic bonding in solder joints.