Abstract:

Improper storage is one factor than can precipitate failures in electronic products, especially in a hostile environment. In this case study, failures were observed in the propulsion logic modules on trains that were stored in Taiwan for nearly 3 years. Failure analysis was conducted to identify the root cause of IC failures. External inspection showed that contaminants were deposited on the external lead frames. The failure modes in the ceramic packages were observed to be open metallization, although both visual inspection and scanning electron microscopy revealed no trace of corrosion or damage to the die surface. Internal inspection of the plastic dual-in-line packages (P-DIP)s revealed damage to the metallization and glassivation on the die surfaces, and contaminants were found at the failure sites. The major failure mechanism was ionic corrosion, probably caused by high humidity as well as the presence of contaminants in the storage environment or from the device themselves.

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