Effect of Different Surface Finishes on Micromechanical Properties of Sac 0307 Solder Joint using Nanoindentation Approach

A Physical and mechanical properties of solder joints on printed circuit boards (PCB) depend on the solder materials and PCB surface metallization. Advances in research and development of lead-free solder materials provide an opportunity to produce solder joint with high reliability. PCB/Cu is a PCB without surface finish used as control sample while the other two, PCB/ImSn (immersion tin) and PCB/ENiG (electroless nickel immersion gold) have been chosen in order to study the solder joint stability. Solder joints on different surface finishes are exposed to high temperature storage (HTS) at 175 degrees C for 1000 h in order to investigate the micromechanical properties changes. Nanoindentation test provides localized micromechanical properties. The hardness changes of SAC 0307 solder joint after HTS is 66 MPa for PCB/Cu, 107 MPa for PCB/ImSn and 45 MPa for PCB/ENiG. PCB/ENiG has shown the minimum changes of micromechanical properties compared to PCB/Cu and PCB/ImSn. The show that PCB/ENiG provides the high stability of micromechanical properties after subjected to HTS at 175 degrees C for 1000 h.