A PoF based methodology to assess the reliability of a sensor module operating in harsh industrial environments

Abstract

This paper presents the use of physics of failure based methodology in combination with finite element analysis (FEA) to assess the reliability of electronic assemblies. Mechanical loads such as vibration and shocks are one of the important causes behind electronic assembly failure and understanding behavior of the PCB and components under vibration is crucial to assess the reliability of the product. In this paper, a condition-based monitoring sensor used in high-speed industrial machines is selected to perform a vibration analysis. First step of the reliability assessment is the failure mode and effect analysis (FMEA) which is a systematic and pro-active method to identify where and how system may fail and analyze the impact of the failures. FMEA study identified the critical components in sensor design such as a supercapacitor, a 40 pin QFN package, a LGA Network module and a standard battery. Finite element model of sensor assembly is built with a commercial software MSC Apex. Modal analysis extracts the first natural frequency as 256 Hz and shows mode shapes for the assembly. Harmonic analysis concludes that supercapacitor is the most vulnerable component under vibration and supercapacitor solder joints as well as leads may see a mechanical fatigue throughout the operation. Estimated fatigue life of the supercapacitor leads and solder joint is > 30 years and lifetime estimations are based on the lifetime model developed in house. It is pertinent to note that combination of FMEA and finite element analysis provides a quick and an efficient way to assess the reliability of the sensor module in its early design stages.