Experimental research on Sn99.0/Ag0.3/Cu0.7 lead-free soldering paste and its board-level packaging joint reliability

For the increase market demand of low- Ag lead-free solder paste, a rosin-based halogen-free flux which is suitable for low-Ag lead-free solder past Sn99.0/Ag0.3/Cu0.7 has been developed. Its board-level package printing and reflow process adaptability. The printing quality of the solder joints were tested using 3D Microscopic examination method, and the gas cavity of the sold joint were evaluated with X-RAY. The board-level product components drop testing, vibration testing and temperature cycling test have been carried out. The electrical reliability of the tested products used as the joint´s evaluating condition. Experiments show that the solder paste´s melting point and wettability meet the actual products requirements. The solder paste has a good printing quality. There is no collapse and bridge phenomenon for the joint. The joint porosity meet requirements of IPC-A - 610D <;25%. Through the drop, vibration and the temperature cycling tests, the solder joints have no peel off, and the electrical function is favorable.