Thermal Conductivity Simulation of Sintered Nano-Silver for High-Power Electronic Devices

Under the working conditions of high-power electronic devices, the heat generated by electronic chips has been attracting much attention to be designed and optimized to be transferred using various methods. Die-attach materials with higher thermal conductivity are preferred to efficiently dissipate the heat generated during chip operation. Optimal thermal management ensures the operational capacity of electronic devices, especially under harsh working scenarios, and improves the reliability of high-power electronic chips for long-term and reliable service. Previous studies have shown that porosity and pore distribution have significant impacts on the heat transfer performance of sintered materials with mesoscale defects. In this paper, a mesoscale finite element model is established to evaluate the thermal conductivity of sintered nano-silver in a typical double-sided cooling packaging structure for high-power modules, exploring the effects of porosity and pore distribution on thermal conductivity. This provides a theoretical guideline for improving the mechanical reliability of electronic packaging materials and structures. Based on the Fourier's law, the thermal conductivity of sintered nano-silver materials is theoretically estimated. To further improve the prediction accuracy in practice by considering mesoscale defects, two boundary conditions (heat flux-in and heat flux-out) are applied in the mesoscale finite element model of the die-attach materials, and the accuracy of the predicted thermal conductivity is verified. Finally, by incorporating additional parameters into the finite element model, the influences of pore characteristics and arrangement on the heat transfer performance of the sintered nano-silver material are discussed and summarized. The results show that pores significantly hinder heat transfer within the material, and heat concentration around the pores causes the temperature gradient inside the sintered layer to become inhomogeneous, leading to uneven thermal expansion and deformation. Therefore, it is recommended to optimize the sintering process and parameters to achieve a more uniform pore distribution and lower porosity. This improvement is crucial for enhancing the heat dissipation of high-power electronic devices, particularly under harsh operating conditions.