Sintered nano-silver die-attach materials have been widely used in high-power electronics packaging because of their high thermal and electrical conductivities. In this study, we characterized the tensile properties of sintered nano-silver particles over a range of strain rates and temperatures, and established the constitutive models. First, 50 nm nano-silver particles were sintered at 275 °C for 50 min as test samples, and their tensile tests were conducted under a dynamic thermomechanical analyzer (DMA Q800) and an IBTC 300SL in-situ mechanical test system respectively with different strain rates and ambient temperatures. Then, both Anand and variable-order fractional models (VoFM) were adopted to analyze the obtained stress-strain data and we studied their fitting accuracy and applicability. The results showed that: (1) The Young's modulus of the sintered nano-silver particles decreased with increasing temperature. In addition, the tensile strengths declined under lower strain rates and higher temperature conditions; (2) both the Anand model and VoFM characterized the tensile stress-strain properties of the sintered nano-silver material well. Compared to the Anand model, the VoFM utilized a simpler formula with fewer parameters and higher precision.@en

In high power electronics packaging, sintered silver nanoparticle joints suffer from thermal-humidity- electrical-chemical joint driven corrosion in extreme environments. In this paper, we conducted aging tests on sintered silver nanoparticles under high-temperature, high-humidity, and high-sulphur conditions. The results show that: (1) the sample under the dry high-sulphur conditions at a high temperature exhibited the highest degree of sulphidation; (2) Reactive force field (ReaxFF) molecular dynamics (MD) simulations of sintered silver nanoparticle sulphidation revealed the sulphidation layer was formed by silver atoms upward migration. This work paves the way for further investigation on sintered silver nanoparticles corrosion considering multi-physics coupling effects.

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In high-power electronics packaging, nano-silver sintering technology has been widely applied due to its excellent electrical and thermal conductivity and its low-temperature packaging and high-temperature operation. In this study, 50-nm nano-silver particles are sintered at 275°C for 50 min and placed under a dynamic thermomechanical analyzer (DMA Q800) with three strain rates (0.001%s-1, 0.01%s-1, and 0.1%s-1) and seven ambient temperatures (-40°C, 0°C, 25°C, 60°C, 120°C, 150°C, and 185°C). Both the variable-order fractional constitutive model and Anand model are adopted to characterize the tensile behaviors of sintered nano-silver particles. The results show that (1) the tensile strength of sintered nano-silver particle samples declines under the lower strain rate and higher temperature; and (2) both the variable-order fractional model and Anand model can well represent the tensile mechanical properties of sintered nano-silver. According to the root mean square error (RMSE) calculation, the fitting accuracy of the variable-order fractional model is slightly better than that of the Anand model. Furthermore, the variable-order fractional model involves fewer parameters, which makes it easier to fit than the Anand model.

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