High frequency wire bonding for PBGA package, a process optimisation approach

摘要

In a plastic BGA package, the glass transition temperature of 170-215 deg C for bismaleimide triazine (BT) substrate puts an upper ceiling to the usable wire bond temperature. To compensate for the limitation in thermal energy, high frequency thermosonic bonding was proposed and successfully demonstrated for plastic BGA wire bonding. Design of experiment (DOE) and response surface methods (RSM) for process optimisation were used; bonded areas were also analysed using scanning electron microscope (SEM). Of the four major bonding parameters investigated, ultrasonic power and bond force appeared to be the most important control factor for wire pulls and ball shear force optimisation. The results show that bonding at low temperature is viable with the use of high frequency transducer wire bonder.