The inadequacy of the traditional power law formula in predicting the growth kinetics of intermetallic compounds at the interface of solder joints in microelectronic packaging

The growth of intermetallic compounds (IMC) at the interface of solder joints in microelectronic packaging is one of the most critical factors affecting the long-term reliability. Traditional studies have shown that IMCs growth curves follow a power-law relationship with an exponent of 1/2 or 1/3 approximately. However, limited research has been conducted to validate the effectiveness of this formula in predicting IMCs growth. Consequently, we investigated the growth kinetics of IMCs under ultra-long-term isothermal aging conditions. Our findings revealed that the power-law formulas derived from fitting failed to accurately predict the subsequent growth of IMCs beyond the fitting process. This inadequacy was attributed to the initial consideration of the IMCs growth rate as infinite. To address this issue, an improved kinetic growth model of interfacial IMCs layer based on ordinary differential equation modeling is proposed. The effectiveness of the proposed model was validated through experiments conducted by ourselves and other researchers, demonstrating significantly improved accuracy in predicting the growth kinetics of IMCs compared to the traditional approach.