Damage Progression Using Speckle‐Correlation and High‐Speed Imaging for Survivability of Leadfree Packaging Under Shock

Abstract

Abstract: In this paper, a methodology to predict failure of electronics under shock and vibration loads has been investigated. Reliability prediction models have been developed using optical feature extraction techniques for 6‐leadfree solder alloy systems. Solder alloy systems investigated include, Sn1Ag0.5Cu, Sn3Ag0.5Cu, Sn0.3Ag0.7Cu, Sn0.3Ag0.7Cu0.1Bi, Sn0.2Ag0.7Cu0.1Bi‐0.1Ni, 96.5Sn3.5Ag. Previously, Digital Image Correlation (DIC) has been used for measurement of thermally‐induced deformation and material characterisation. In this paper, DIC has been used for transient dynamic measurements, and optical feature extraction. Board assemblies have been subjected to shock‐impact in various orientations including the zero‐degree JEDEC drop and the vertical free‐drop. Transient deformation has been measured using both DIC and the strain gages. Measurements have been taken on both the package and the board side of the assemblies. Accuracy of high‐speed optical measurement has been compared with that from discrete strain gages. Package architectures examined include‐flex ball‐grid arrays, tape‐array ball‐grid arrays, and metal lead‐frame packages. Explicit finite‐element models have been developed and correlated with experimental data. Three models were developed: smeared property models: Timoshenko‐beam models: and explicit sub‐models. The potential of damage identification and tracking for various solder alloys has been investigated. Data on the identification of damage proxies for competing failure mechanisms at the copper‐to‐solder, solder‐to‐printed circuit board, and copper‐to‐package substrate has been presented. Design envelopes have been developed based on Statistical Pattern Recognition (SPR). The design‐envelope is intended for component integration to ensure survivability in shock and vibration environments at a user‐specified confidence level.