Study on bonding process parameters affecting Cu bump shape based on design of experiment Method

Three parameters, bonding time, bonding force and ultrasonic energy were chosen as three controlled factors. By using an L9(34)orthogonal array the copper stud bump solder joints which have 9 different combinations of process parameters were designed. The numerical models of 9 copper stud bumps were developed using the ANSYS/LS-DYNA. By using the element of SOLID164 finite element the shaping process was simulated to get the copper stud bump diameter and height under the nine different process parameters combinations. Copper stud bump diameter and height were analysed through range analysis and variance analysis. The result shows that of the three process parameters, the copper height was affected by bonding time, bonding force and ultrasonic energy in a descending order and the copper diameter was affected by bonding force, bonding time and ultrasonic energy in a descending order. With 95% confidence, bonding time and bonding force has a significant effect on the copper height whereas ultrasonic energy has little; bonding force and ultrasonic energy has a significant effect on the copper diameter whereas bonding time has little.