Reliability Research Of Board Level Interconnection System Under Drop Impact Load

With the continuous development of electronic devices toward miniaturization and portability,the size and thickness of electronic product housings have been continuously reduced,making electronic products' ability to withstand impacts weaker.In board-level interconnect systems,solder joints are the most vulnerable parts to damage due to loads.Solder joint failure is the main reason for electronic products and equipment not working properly.During the transportation and use of electronic products,board-level interconnect solder joints are not only subject to drop impact loads,but also subjected to thermal-mechanical coupling(temperaturedrop coupling),which has raised the reliability of board-level interconnect systems higher requirement.Therefore,this article uses the finite element simulation method to study the board-level drop test standard and the reliability of the board-level interconnection system under the thermo-mechanical coupling effect.Drop test is one of the important methods to verify the reliability of solder joints.This article tested the drop test standard Standard 2003 issued by JEDEC(Joint Electron Device Engineering Council)in 2003,and verified the drop impact simulation model through the test strain monitoring results.The ANSYS finite element software was used to compare and analyze the two drop test standards Standard 2003 and Standard 2016 released by JEDEC in 2003 and 2016.The results show that Standard 2003 and Standard 2016 are basically the same in terms of solder joint stress.There are significant differences in amplitude,strain amplitude,strain rate,and decay rate.Standard 2003 produces higher amplitude and strain magnitude,while Standard 2016 produces higher natural frequencies,strain rates,and decay rates.It can be found from the simulation results that the magnitude of the stress is not only dependent on the strain,but also related to the strain rate of the PCB.The strain is small,but the higher the strain rate,the larger the stress.Different power density loads are applied to the solder joints in the board-levelinterconnect system,so that the maximum temperature of the system reaches 50 ?,75 ?,and 100 ?,respectively,and the drop simulation is performed.The influence of thermal load on the reliability of the board-level interconnect system drop impact was studied.The simulation results show that after applying a thermal load to the solder joints,the temperature of the solder joints is higher,the temperature of the edge of the PCB is lower,and the temperature distribution of the PCB is uneven.Compared with a single drop impact,the application of thermal load reduces the first-order natural frequency of the PCB board and reduces the solder joint stress.And as the system temperature rises,the first-order natural frequency and solder joint stress of the PCB are decreasing.The maximum strain at the B1 position in a single drop impact field is smaller than the maximum strain at the B1 position in the thermo-mechanical coupling field.As the coupling temperature increases,the maximum strain at the B1 position in the thermo-mechanical coupling field increases.It was found through the established solder joint life model that as the system temperature increased,the solder joint life was increased.The reason for the analysis was that due to the application of the thermal load,the solder joint temperature increased,the plastic properties of the solder joint were improved,and the solder joint withstand increased ability to drop impact.