Today's powerful DSP based hearing instruments demand both high density and low cost microelectronic packaging solutions. In turn, this demand drives innovation and substantial collaboration among design and manufacturing personnel and suppliers. Conventional design and process envelopes are challenged and new problems arise. Rapid failure analysis and root cause identification are essential in this global, fast-paced development arena. Here we introduce a novel high density multichip module designed for placement onto a flexible, folded hearing aid SMD assembly and discuss the challenges faced by the design team. Delamination, electrochemical migration, and thermal stress failure mechanisms identified during design verification testing are examined, along with the techniques and tools of failure analysis and problem solutions.

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