Delamination and crack were considered as significant failures in electronic packaging. For these circumstances, Modified Crack Closure Integral method was tested and applied to determine crack growth rate and for the purpose to understand failures. TQFP package was successfully verified by using the method. A PBGA package was modeled for thermal distribution and moisture concentration in order to calculate vapor pressure acted on crack. The energy release rate was the main concern among fracture parameters, which had been proven fully related with vapor pressure and crack length ratio in popcorn cracking.