Sn-Ag-Cu lead free solder SMT process

In this paper several design of experiment are used to evaluate the SnAgCu alloy, the procedure of these experiment are done through normal surface mount process such as screen printing and reflow. In this study, component like BGA is used to simulate normal SMT process. The first investigation topic is screen printer parameter. The study of printing parameter includes which how to evaluate the printing results and compares the results with traditional printing process. The second topic is reflow profile. The reflow profile is a very import issues in lead free solder because of higher peak temperature that will impacts the components and PCB. In the study of reflow profile, an important part of the reflow is the inspect criteria of temperature profile. Some test methods like electrical test, cross-section, X-ray inspection, peeling test, were used to examine solder joint quality. The study compares the differences of SnAgCu solder with Sn/Pb solder (traditional reflow profile). Printed circuit board is an important part of the entire solder joint system. Two types of test board surface finish, Ni/Au surface finish and OSP surface finish, were studied for the effect on the solder joint quality. Furthermore, the study also compares the difference of atmosphere, air and nitrogen, in SnAgCu soldering process.