Influence of the Cu substrate surface energy on lead-free solder paste wetting properties

Dewetting is the phenomenon in which the molten solder withdraws from a surface that has been previously wetted, resulting in a typical combination of dewetting regions and irregularly shaped solder droplets. It is known from literature that key factors which influence on this phenomenon are high interfacial tension between alloy and wetting surface, thermodynamics of the wetting process and inadequate Cu substrate surface energy. In the paper will be presented results of Cu substrate surface energy determination and its influence on lead-free solder paste wetting properties. These results will allow better understand the reason for dewetting phenomenon of lead-free solder pastes.