Reliability Analysis Of Three Packaging Modules Using A Multi-physics Coupling Method

Electronic product is used in many fields. The size of electronic packaging decreases while its input power increases, therefore, much heat would be generated. High temperature would have a bad influence on the performance of electronic packaging, even burn the electronic products. Meanwhile, due to the mismatch of CTE(coefficient of thermal expansion), high temperature gradient would cause thermal strain and stress, leading to crack, and delamination. Therefore, it is very important to investigate the reliability of electronic packaging. Electronic packaging is a multi-disciplinary field. In this paper, based on theoretical study, numerical analysis and experiments, the reliability of several types of electronic packaging were analyzed by using multi-physics coupling method.The fluid-thermal coupling method was discussed. The maximum power loss is 131W which was obtained by electric simulation. It was then used as an input load in the fluid-thermal coupling analysis. The results showed the traditional cooling method cannot meet the requirement of thermal management. Therefore, a micro channel inside the Cu base plate was designed. The simulation results showed when the inlet velocity was 10m/s, the junction temperature of the chip maintained at 100℃. Therefore, the micro channel was found to have good heat dissipation ability.Thermal-stress coupling method was investigated. And this method was used in the reliability analysis of TSV(Through Silicon Via) under thermal cycling load. The influence of copper flange pad and shape of solder joint on the reliability were analyzed. The results showed the lower copper flange height leads to a more reliable TSV. Regarding to the shape of solder joint, TSV has good reliability when the shape of the solder is cylinder. As the radius of the solder increases, its reliability decreases. Also it was found the maximum stress was located at the interface between Si and SiO2. The influence of each material size on the reliability was determined by Finite Element Analysis. And the height of Cu affects the maximum stress most. Based on the analysis above, the size of TSV was optimized and the maximum stress was reduced from 72.5MPa to 67.7MPa.Finally, the importance of fluid-thermal-stress coupling method was analyzed. For the conventional simulation method, when H increase from 5W/m2*K to 10W/m2*K, the maximum temperature decreases from 165.38℃to 70.387℃. A fluid-thermal-stress coupling method could avoid the random selection of heat transfer coefficient, and the resulting distribution of temperature and stress would be more accurate. To verify the validity of this method, an experiment was conducted. The temperature difference between the simulation and experiment is less than 10%, which indicates that this coupling method is valid. Then this method was used in the reliability analysis of PBGA(plastic ball grid array), the results showed the heat transfer coefficient is different at different locations.The work in this thesis could provide some guidance to the reliability analysis and design process of typical electronic packaging.