AN INVESTIGATION OF KEY FACTORS AFFECTING SOLDER MICRODROPLET DEPOSITION

This paper combines a theoretical model with experimental measurements to elucidate the role of key operating parameters affecting solder mi crodroplet deposition in the electronics manufacturing industry. The e xperimental investigation is used to evaluate the final deposit (bump) shapes and trends predicted by the model. The effects of substrate te mperature, material composition, layer thickness, and thermal contact resistance (including surface oxidation) are delineated. Solder-deposi t shape comparisons between experiments and modeling suggest that the value of thermal contact resistance may change with process parameters , and is probably dependent on the solder phase. It is established tha t inferences regarding the overall shape or solidification times of so lder bumps using limited modeling trends should be made only after car eful consideration of the substrate composition, accurate representati on of the thermal contact resistance, and adequate resolution of the f luid dynamical oscillatory motion and its effects on solidification ra tes. It is shown that modeling tools can be used in conjunction with e xperiments to promote our fundamental understanding of the transport p rocesses in the complex solder jetting technology.