Research Of Electrochemical Corrosion Behaviors Of Lead-free Solders

Lead-free has become the developing tendency in electronic packaging and other related welding technology because lead and its compounds are harmful to human and environment. As we known that Sn-Ag-Cu lead-free solders have become the preferred succedaneum for their excellent physical properties and heat stability, so they are used worldwide as a new generation of representation. While Sn-Zn-Cu lead-free solders have the similar melting point with lead-contained solders, the researches on the corrosion behavior of them have been put on the topic gradually. Based on the structure of both solders, this paper explores the influences of different environmental conditions, temperature and adding elements on solder corrosion behavior by electrochemical analysis method and material analysis technique. A feasible suggestion to optimize component of solders is made when putting attention to improve the combination properties. And helpful data about the solders corrosion is expected to gain for application of them.The results are as follows:1. The corrosion rate and current density of Sn-Ag-Cu lead-free solders are sensitive to temperature, but it is not for corrosion potential;The corrosion rate is increased with increasing temperature for all solders; Corrosion resistance is affected more obvious for adding Ag element than Cu added at all experimental temperature.2. The complex form of general and local corrosion is occurred for Sn-Zn eutectic solders, so the corrosion rate is so fast;The corrosion form of Sn-Zn-Cu solders is same with Sn-Zn eutectic solders, but the corrosion potential is increased for adding Cu element and the corrosion potential is increased with the increasing content of Cu element for Sn-9Zn-xCu; The corrosion form is changed from local corrosion to general corrosion because of adding Cu element, thus corrosion resistance of Sn-9Zn-xCu is improved accordingly.