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Current leakage failure of conformally coated electronic assemblies

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conference contribution
posted on 16.01.2009, 16:59 by Guangbin Dou, Patrick WebbPatrick Webb, David Whalley, David HuttDavid Hutt, Antony R. Wilson
Conformal coatings are widely used on circuit board assemblies as an attempt to improve reliability and to ensure high insulation impedances, which are for example demanded by low current consumption battery operated RF circuitry. However, components, such as small ceramic capacitors, have occasionally been found to fail in some applications, particularly when covered with a thick silicone conformal coating. This is thought to be due to the diffusion of water through the coating to the capacitor surface where it then combines with solder flux residue, or other organic or ionic contamination left on the components, thereby dramatically increasing the effective component leakage current. The primary objective of this experimental research is therefore to establish a clear understanding of the effects of moisture exposure on the surface insulation resistance (SIR) of conformally coated printed circuit board (PCB) assemblies. This has been achieved through leakage current measurements on multilayer ceramic capacitors during storage in an environmental chamber during testing similar to IPC standards for non-component loaded boards.

History

School

  • Mechanical, Electrical and Manufacturing Engineering

Citation

DOU, G..... et al, 2008. Current leakage failure of conformally coated electronic assemblies. IN: Proceedings of the 2nd Electronics Systemintegration Technology Conference (ESTC), Greenwich, 1st-4th September, vol. 2, pp. 1213-1218

Publisher

© IEEE

Version

VoR (Version of Record)

Publication date

2008

Notes

This is a conference paper and the definitive version is also available at: http://ieeexplore.ieee.org. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.

ISBN

9781424428137

Language

en

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