TAB inner-lead bond process characterization for single-point laser bonding

Characterization of new equipment and processes is necessary prior to initiation of a production effort using a developing technology, such as tape-automated bonding (TAB). In this paper, results are presented for a set of experiments used to characterize a process for performing inner-lead bonding (ILB) using a continuous-wave (CW) laser. Three key parameters were selected for initial analysis: the force exerted by the bonding stylus; the laser power; and the on-time of the laser. Using a Box-Behnken statistical design for the experiment, an efficient set of tests was derived. Four sets of experimental samples were fabricated, to be used for the as-fabricated testing, high-temperature aging, and thermal cycling; only the as-fabricated results are reported here. Using a Design-of-Experiments software package for the PC, a quadratic equation was derived from the data explicitly defining the relationships among the three parameters and relating them to bond strength. Through a rearrangement of the existing data, an additional correlation was derived for lead misalignment. Using the techniques of surface response methodology, a response surface was created, showing the optimum operating region for the ILB process based on the parameter range chosen. Initial operating parameters are reported for continuous-wave laser bonding