Effect of Moisture in a Non-conductive Glue on the Electrical Performance of a Cavity Package

This study discusses the experimental evaluation and simulation done on a cavity package to understand how moisture in a non-conductive (NC) glue found accidentally dripped on two adjacent conductive bond wires, contributed to a leakage problem encountered. In the experiment, a certain amount of glue was intentionally dispensed on two adjacent conductive wires and moisture was introduced to the package in a humidity chamber before leakage test was performed. Leakage test was also done after subjecting the package to dry baking process. In addition, a finite element analysis (FEA) simulation of the diffusion of moisture into the NC glue was conducted to further understand the moisture absorption of the glue with respect to time as well as the impact of glue size.Evaluation results showed that when moisture was introduced to the package, electrical leakage was observed. Thus, the original problem was replicated. The effect of moisture was further confirmed by subjecting the unit to dry baking process to drive out the moisture inside the package. The initial electrical leakage problem of the package was gone as if the package recovered its original state or performance confirming the effect of the NC glue on this kind of package. This study showed that foreign materials introduced by way of NC glue drippings in a cavity package can cause electrical leakage problem in the presence of moisture contrary to the general assumption that the NC glue is harmless because it is not electrically conductive.