Paste. Ball Production Process Improvement To Improve The Yield

This thesis investigates how to improve the production reliability and yield when the lead-free solder used in production welding process. In order to protect the Earth's ecological environment, the EU will be implementation the Restriction of the use of certain hazardous substances in electrical and electronic equipment (RoHS) on July 1,2006, it will forbid the electrical and electronic products which contained lead enter the EU market, compare with lead-free solder and lead solder, lead-free solder with a high melting point, solder wetting performance is poor, it easily lead to solder joint product of self-calibration capability, tensile strength, shear strength cannot meet the requirements, so some process need be improvements, the last of the thesis focuses on two cases about the Voids in Solder Joints and poor ball co-planarity.The thesis is focus on the two kinds of defects, the Voids in Solder Joints and poor ball co-planarity. Voids generated by the evolution of volatile ingredients of fluxes and solder pastes and insufficient time to escape. much more voids in solder joints is poor performance for production, The current IPC-610-D specification allows a maximum of 25% voiding by area; this thesis describes that we can optimize the temperature profile and improve the paste viscosity to reduce voids occurred; poor ball co-planarity caused many product rejected, we can optimize the solder paste printing quality, Reflow temperature profile and cooling rate to improve the chip co-planarity, the goal improve from 0.1% to 0.05%. It should be improve the product yield.