Reduced Relative Humidity (RH) Enhances the Corrosion-Limited Lifetime of Self-Heated IC: Peck’s equation Generalized

Since the early 1980s, highly accelerated stress tests (HAST) have been used as an industry-standard method to qualify the correlated moisture-enhanced, and temperature-accelerated electrochemical bond wire failures of non-hermetically packaged Integrated Circuits (IC). In this regard, empirical Peck’s equation has traditionally been used to translate the HAST failure rates to the corresponding failure rates under application-specific use conditions. Unfortunately, this use-condition lifetime projection is challenging because self-heated ICs correlate relative humidity (RH) and temperature (T) in a way that is not explicitly accounted for by Peck’s equation. Here, we develop a predictive and self-consistent reliability modeling tool that: (i) explicitly accounts for the intermittent IC self-heating data collected from laptop/device/cellphone users’, moisture ingress in the filler tunable epoxy molding compounds (EMCs), and Cu-Al bond wire corrosion in an integrated way; (ii) demonstrates how the asymmetry between on and off-state heating leads to dramatic suppression of the effective RH experienced by an integrated circuit; and most importantly, (iii) identifies that the corrosion of Cu-Al bond wire occurs in spikes during the on-off transition when both RH and T are high. Our integrated, self-consistent predictive Multiphysics model provides deep insights into the Cu-Al bond wire failure and suggests a pathway to application-aware Generalized Peck’s equation relevant for self-heated ICs under arbitrary operating conditions.