Reply the concerning about the failure analysis method

    As we know that the samples from substrate side has been grounded down to be thinner, it has resulted in an uneven surface. Due to this uneveneess, when you removed the chip from the top side, the microbump pad may not all to be exposed at the same surface level. This non-uniformity could potentially affect the open short test results as they probably not to make the consistent contact with their corresponding counterparts.

    The thickness of the samples after removing chip also is very concerning. Cold mounting may not be suitable for extremely thin samples. This method cannot precisely targeted to the desired positions or it does not compromise the sample's structural integrital. The air bubbles or voids may form during embedding process, affecting subsequent analysis. It should be more risky than previous PFA proposed by PTI.

    I confirmed with PTI related person, PTI did not have available test kits with fine probe. Anyway,  I still asked these questions to Shinko Japan, we are still waiting their answers. I can predict the answer is not promising.