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      08-20-2011, 11:40 AM   #19
First Lieutenant

Drives: 2006 330i E90
Join Date: Aug 2011
Location: So Cal

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The most common coating used in high end electronics is parylene. It is a good insulator (dielectric) to prevent local arcing- other common insulators do not go down conformally and eventually cause local arcing over time as the insulation degrades. Parylene has low vapor pressure but may evaporate over time. Also, if there is a black-colored material underneath the electronics module, where it is bolted and welded, it is most likely a thermal interface. It is normally used if the housing is plastic (a metal housing won't need it). Do you see any degradation of the interface material, if it is present?