关键词: 无铅焊料, 金属间化合物, 回流焊, 焊点

Abstract: Taking the soldering of BGA substrate as the research object, the variation trends of intermetallic compound (IMC) thickness and solder jointstrength after multiple reflow soldering between lead-free solder (SAC305) and NiPdAu plating layer are analyzed. The experimental results show that by optimizing the reflow soldering temperature curve between SAC305 solder balls and Ni layer pads, the thickness of IMC layer can be controlled at about 2 μm, and the presence of Pd in the plating reduces the activation energy of (Cu, Ni, Pd)₆Sn₅ growth and inhibits the formation of bad IMC at the same time. After multiple reflows, the microscopic interface and shear strength of SAC305 solder balls and NiPdAu plating layer still maintain a good level. The solder joints still have high reliability after reflow soldering for 3 times.

Key words: lead-free solder, intermetallic compounds, reflow soldering, solder joint