Simulation Modeling And Mechanism Analysis Of Thermal Fatigue Life Of CSP Packaging Based On PLP Process

CSP(chip size package,or chip scale package),namely chip size package,is one of the most advanced integrated circuit packaging forms at present.CSP packaging based on PLP(panel level package)process has the advantages of higher packaging efficiency,lower cost,lower packaging parasitism and better performance because the size of the panel used is large and there is no need for frame and substrate.It mainly replaces the bonding lead and copper column connection in the traditional integrated circuit packaging process through RDL(redistribution layer)wiring.In the CSP packaging based on PLP process,the solder layer is the key link between the device and the circuit,and its thermal fatigue life has become an important factor affecting the reliability of the device.In this thesis,the CSP packaging based on PLP process is taken as the research object,and the fatigue life of the welding layer under the condition of temperature cycle is simulated and analyzed by using the finite element software ANSYS,in order to obtain the practical simulation results,and optimize the simulation model and fatigue life analysis theory.The specific contents of this thesis are as follows:The tensile strength and thermal expansion coefficient of PCB samples are tested,so that the simulated material parameters are closer to the actual situation.The finite element model of CSP packaging based on PLP process is established,including single chip model and dual chip mode;Anand unified viscoplastic constitutive model is used to simulate the stress and strain of SAC305 welding layer under the temperature cycle condition of-40??125?,and the fatigue life of welding joints is predicted by darveaux welding joint fatigue prediction model based on energy;The fatigue life of welding layer under different support constraints is simulated.Compared with the experimental results,the simulation conditions are more in line with the actual situation;With DFN4 × 4.Compare the solder layer fatigue life of packaging model,and compare whether CSP packaging based on PLP process has advantages in thermal fatigue reliability;The effects of different plastic packaging thickness and different welding layer length on the thermal fatigue life of welding layer are analyzed,and the package size that can improve the fatigue life is found out;According to the simulation and experimental results,the fatigue life prediction model of darveaux solder joint is optimized,and the optimization model which can better simulate the fatigue life of CSP packaging welding layer based on PLP process is obtained.