I have some 1.25 mils Al wire bonding chip on board process. After epxoy-based encapsulation, I do some aging test. How can I "see" or prove that there is a "wire break" exist due to the tension of thermal cycling? How can I know the failure is caused by die, die attached paste, wire bonding, encapsulant, popcorn, or thermal mismatch? Could someone please list some of theanalysis methods and providers?