Fatigue Prediction of Electronic Packages Subjected to Random Vibrations

Abstract

In modern automotive control modules, mechanical failures of surface-mounted electronic components such as microprocessors, crystals, capacitors, inductors, transformers, ball grid array packages (BGA), quad flat packages (QFP), and chip-scale packages (CSP) are major road blocks in the design cycle and reliability of the product. This paper presents a general approach for failure analysis and fatigue prediction of electronic component like QFPs under automotive vibration environments. The mechanical performance of this package was studied through a finite element modeling approach for a given vibration environment in an automotive application. The vibration simulation provides system characteristics such as modal shapes, modal frequencies, and dynamic responses, including displacements and stresses. By using the results of vibration simulation, fatigue life is predicted based on Miner's cumulative damage ratio and the three-band technique. Detailed (local) model of the lead wire joint is built to correlate the system level model to obtain solder stresses. On the test vehicle, a 160-pin gull-wing lead plastic QFP was chosen to illustrate this approach for failure analysis and fatigue life prediction. From the analysis, it was found that the life used up by the lead wires was 11.6% of the 4-h vibration test.