Board Level Drop Test Analysis Based on Modal Test and Simulation

Solder joint reliability in drop test is crucial for handheld systems, such as mobile phone, digital camera, and MP3 player. In recent years, a lot of experiments and simulations have been carried out by researchers to study board level drop test, and many useful results have been obtained. Regarding mechanical simulation and analysis, there are still two challenges: How to design drop test printed circuit board (PCB) based on dynamic simulation and analysis? How to get accurate elastic modulus of PCB, especially damping parameters, as property inputs for drop test simulation? In this study, an approach based on systematic modal tests and analyses is used to address these two challenges. First, modal dynamic simulation is used to design the test board to meet drop test requirements. Second, modal tests are conducted on drop test board in order to validate dynamic simulation and measure structural damping parameters and overall board elastic modulus as well. Adopted directly in drop test simulation, the measured damping parameters and elastic modulus are proved to be accurate. It is verified through comparison between the finite element simulation and real drop test results. With the modal tests and simulation method established here, drop simulation becomes very simple and accurate, and test board design and characterization are also simplified. Thus, considerable drop test experiment and simulation fine tune, and validation work can be saved.