Research on the Reliability of Board Level Interconnect Solder Joints under Thermal-Mechanical Coupling

In this paper, through the method of finite element simulation, different power density loads are applied to solder joints in the board level interconnection system to make the maximum temperature of the system reach 50°C, 75 °C and 100°C respectively, and then the drop simulation is carried out to study the reliability of the board level interconnection solder joints under thermal-mechanical coupling. The simulation results show that compared with single drop impact, the application of thermal load reduces the 1st eigenfrequency of PCB and reduces the solder joint stress. With the increase of system temperature, the 1st eigenfrequency of the PCB and the solder joint stress is decreasing, but the solder joint life is increasing. The stress analysis in the height direction of the solder joint found that the bottom surface of the solder joint connected to the PCB board is the location of the largest stress on the solder joint. It is inferred that when the board level interconnection system is impacted by drop, this position will be damaged first.