Improving Wire Sweep Performance by Measuring Degree of Cure of Epoxy Mold Compounds

The choice of epoxy mold compound (EMC) for an electronic package is based mostly on how much protection it provides to the active components in the package. But the choice is not a straightforward process. Rather it is mostly trial and error using different assembly parameters to find the most robust material while assembly defects are monitored. One such defect associated to EMC processing is wire sweep, and many studies have shown that it is mainly caused by viscosity changes in the EMC. In this study, samples of EMC in various stages of shelf life and staging times were analyzed for degree of cure using a method called differential scanning calorimetry (DSC). Samples are then processed at assembly for wire sweep measurement. It was found out that degree of cure increases with staging time at different rates for each shelf life. It was also found out that wire sweep did not only increase with degree of cure but it was also found to be predictable with respect to the latter. Using this information, the age and staging limit for each material was identified that would not cause wire sweep issues.

Hardness Test on an Epoxy Mold Compounds of a Quad Flat No Lead Package Using the Depth Sensing Nanoindentation

This study focuses on the effect of stress and load towards hardness at epoxy mold compounds (EMCs) of a Quad Flat No- Lead (QFN) package using indentation technique. A series of three points bending cyclic test were performed with four different loads between 60 N to 120 N on QFN package. The nanoindentation with the maximum load of 300 mN was indented at five locations that perpendicular to the stress line on EMCs of QFN package after three points bending cyclic test were performed. The findings showed that the mean value of hardness was varied with load and stress. Higher load and stress were found to be not affected by hardness of EMCs. From the results, it is believed that the applied load and stress not play a role towards the hardness of EMCs. A polynomial relationship was plotted and shown that correlation of coefficient (R2) between stress and hardness of the studied EMCs was found to be at 97%. Finally, the finding suggested that a close correlation between the stress and hardness since it correlation coefficient gave a higher value with the polynomial relationship.