Molten droplet solder bumping as a new type bumping method is developed in recent years. In this paper, the basic process and phenomenon of this method was investigated. The interfacial reaction between 63Sn37Pb droplet and Au/Ni/Cu pad was analyzed by SEM, that morphology of intermetallic compounds at interface is strongly influenced by initial temperature of solder ball. Results of the calculation have shown: initial temperature of solder ball was the main factor for bump fabrication. The pad temperature field was analyzed using finite element method (FEM).