Simulation research on gold stud bump forming

Abstract

Gold stud bump process provides a good solution for high-power LED's package, which can meet many requirements that the existing methods cannot achieve. To begin with, it is 100% lead-free packaging. Then, it can ensure LED's junction temperature. Next, it can run in pulse, high power or continuous condition. In the end, it is compatible with SMT, and it can bear the reflow temperature three times using lead-free solder. In order to ensure a good operation in the fabrication process, we need to design some key parameters on Gold Stud Bump forming. These parameters include bonding pressure, ultrasonic energy, bonding temperature, bonding time and transverse shearing stress in the process of cutting off gold wire using capillary. This paper processes a dynamic simulation by finite element method. In the simulation process, every gold stud bump contour changes and the process of the change of stress and strain can be observed in real time. Then, the no-contact measured data in the same condition are obtained by experiment. Next, discrete points' data of gold stud bump sample surface are acquired according to the corresponding calculations. Following the data are converted to an appropriate structure that Solidworks software can identify and imported to Solidworks software, a three-dimensional shape model is rebuilt. The corresponding simulation result is compared with the key section's data of the gold stud bump which obtained from the rebuilt model slice. The simulation result of gold stud bump is revised by the error. Finally, we can get an effective simulation finite element model on gold stud bump forming. It will provide theoretical support for choosing suitable process parameters to form a gold stud bump.