Health Monitoring for Damage Initiation & Progression during Mechanical Shock in Electronic Assemblies

Abstract

Electronic products may be subjected shock and vibration during shipping, normal usage and accidental drop. Highstrain rate transient bending produced by such loads may result in failure of fine-pitch electronics. Current experimental techniques rely on electrical resistance for determination of failure. Significant advantage can be gained by prior knowledge of impending failure for applications where the consequences of system-failure may be catastrophic. This research effort focuses on an alternate approach to damage-quantification in electronic assemblies subjected to shock and vibration, without testing for electrical continuity. The proposed approach can be extended to monitor product-level damage.In this paper, statistical pattern recognition and leading indicators of shock-damage have been used to study the damage initiation and progression in shock and drop of electronic assemblies.Statistical pattern recognition is currently being employed in a variety of engineering and scientific disciplines such as biology, psychology, medicine, marketing, artificial intelligence, computer vision and remote sensing [Jain, et. al. 2000]. The application quantification of shock damage in electronic assemblies is new.Previously, free vibration of rectangular plates has been studied by various researchers [Leissa 1969, Young 1950, Gorman 1982, Gurgoze 1984, Wu 2003] for development of analytical closed-form models. In this paper, closed-form models have been developed for the eigen-frequencies and mode-shapes of electronic assemblies with various boundary conditions and component placement configurations. Model predictions have been validated with experimental data from modal analysis. Pristine configurations have been perturbed to quantify the degradation in confidence values with progression of damage. Sensitivity of leading indicators of shock-damage to subtle changes in boundary conditions, effective flexural rigidity, and transient strain response have been quantified. A damage index for Experimental Damage Monitoring has been developed using the failure indicators.The above damage monitoring approach is not based on electrical continuity and hence can be applied to any electronic assembly structure irrespective of the interconnections. The damage index developed provides parametric damage progression data, thus removing the limitation of current failure testing, where the damage progression can not be monitored. Hence the proposed method does not require the assumption that the failure occurs abruptly after some number of drops and can be extended to product level drops.

First Principles Estimation of Shock Tube Tests on Nanoreinforced Composite Materials

“…developed an approach for analyze the shock damage initiation and progression, based on closed-form energy models, explicit finite elements, and statistical pattern [6]. Using a linear acoustic plane wave assumption, Li and Hua approximately solved the transient vibration of an elastic laminated composite cylindrical shell with infinite length exposed to an underwater shock wave [7].…”

On using robust Mahalanobis distance estimations for feature discrimination in a damage detection scenario

“…It is a covariance-weighted squared measure of the distance (as opposed to, say, the unweighted Euclidean distance) that a candidate outlier feature set is from the central tendency of the baseline feature set. Researchers have used the MSD with multivariate feature sets such as transmissibility spectral lines, 6 autoregressive model errors or coefficients, 8 ultrasonic guided wave features, 9 power spectral densities peak shifts, 10 energy signatures from wavelet decomposition, 11 and unit influence lines, 12 among many other studies.…”

High strain rate constitutive behavior of SAC105 and SAC305 leadfree solder during operation at high temperature

“…High speed data acquiring system has been built to measure transient deformation of lead free materials at high strain rate. In the past, Digital Image Correlation (DIC) has been widely used to measure full field displacement and strain, when electronic products exposed to drop and shock events (Lall [2008(Lall [ 19 , 2009 ]). In this study, the high strain rate properties of Sn1Ag0.5Cu (SAC105), Sn3Ag0.5Cu (SAC305) lead-free solder alloys at high temperatures have been measured.…”