Adhesive stabilised and pure flip chips on various substrates under thermocycling

The paper presents numerical simulations and experimental investigations of flip chip modules having silicon, alumina ceramics, polyimide or polyester foil, or epoxy glass laminates as substrate material under thermo cycle test conditions. Some of the flip chip modules were stabilised additionally by filling the remaining gap between chip and substrate with an epoxy underfiller. The presented results concern the stress distribution in the joints as basis of their shape optimisation for the modules without underfiller as well as the evaluation of the metallographic cross-sections of the joints before and after the thermo cycles. Both, the simulations and the experiments, lead to the unambiguous result: The flip chip modules can be made reliable enough for industrial application in all cases with the help of the underfiller.