Shock and Dynamic Loading in Portable Electronic Assemblies: Experimental Results

The development of portable electronics poses design challenges when evolving new designs for high strain-rate life cycle loading, such as in drop events, blast events, vibration, ultrasonic process steps, etc. This paper discusses an experimental investigation of the transient response of a portable electronic product and its subassemblies to dynamic mechanical loading encountered in drop and shock conditions. The portable electronic product tested in this study consists of a circuit card assembly and a battery pack supported in a two-piece plastic housing with a separate battery compartment. Dynamic loading, consisting of various shock profiles, is applied using an electrodynamic shaker. A number of drop tests are also conducted on a drop tower. Fourier transform technique (FFT) is utilized to analyze the dynamic response of the printed wiring board and the plastic housing in the frequency domain. Tests at the subassembly level are used to study the dynamic response of the individual constituents. The nonlinear interactions due to dynamic contact between these subassemblies are then investigated through shock and drop testing at the system level. These results will be used in a subsequent study to investigate the ability of finite element models to accurately capture this transient response of complex portable electronic assemblies under shock and drop loading. The long-term goal of this combined study is to demonstrate a systematic modeling methodology to predict the drop response of future portable electronic products, so that relevant failure modes can be eliminated by design iterations early in the design cycle.