Influence of material combinations on delamination failures in a cavity-down TBGA package

In this study, we have examined the occurrence of different failure types depending on the compound and die-attach material choice in a cavity-down tape ball grid array (TBGA) package. Qualification of the different products is performed by temperature cycle tests to trigger the different failure modes. Samples are decapped to examine the occurrence of passivation crack, wire shift, and/or wire break. Scanning acoustic microscope measurements are performed to examine the occurrence of delamination. Meanwhile, a parametric three-dimensional finite element model is developed to predict the delamination driving stresses for the different material combinations in the cavity-down TBGA package. In some combinations of compound and die-attach, the package performed poor with only one combination without failures. The results of the finite element calculations indicated the possibility of interfacial delamination for different material combinations. Our results show that the reliability of the cavity-down TBGA package is strongly depending on the material combinations, and the developed simulation models can be used to assess the possibility of delamination failures as the consequence of using different material combinations. Using these simulation techniques, cost- and time-expensive reliability tests can be reduced to a minimum.