High Acceleration Dynamic Methodology for Board-Level Shock Solder Joint Reliability Approach

With the development of the science and technology industry, the trend of miniaturization and multi-function integration in handheld and head-mounted smart glasses has become a more popular topic, in case of devices dropped from a high place will suffer severe acceleration (G) generated by mechanical impact to ground, owing to its body configuration of higher integration density and heavier weight. Meanwhile, the inside electronics might be solder joint damaged because the stresses exceed its solder material ultimate strength, and the electronic motherboard plays an important role of transmission buffer under shock energy. Therefore, board level shock reliability test is taken into account to ensure products quality before the mass production, and industries seek to realize the precisely reliability life prediction methods. In this paper, firstly we focus on the PCB (Print Circuits Board) with 2:1 aspect ratio, attach strain gages to measure the in-plane behaviors and PCB peak deformation in shock duration, acceleration range of 1,500G to 10,000G are taken into consideration with recording the specific shock height, further link the response data into the nonlinear oscillation methodology to come out the equation parameters. The following FEM (Finite Element Method) electronics life prediction model will be cited and verified in accuracy enhancement. In order to deeply understand the PCB instant shock phenomenon, we introduce a high-speed photography technology to conduct non-contact measuring analysis under 10,000G shock energy, obtain PCB out-of-plane peak deformation value, oscillating waves and dynamic shapes. In addition, we show the relationship of PCB dynamic viscous damping system, natural frequencies, accelerations and damping ratios. Finally, this study found out the PCB damping ratio 86% highly increasing from 1,500G to 10,000G. Displayed the achievement of modified FEM constitutive model uses in ANSYS LS-DYNA, accurately approach PCB dynamic behavior, narrow the calculation errors of electronics solder joint life prediction on shock reliability.