Iodine vapour based quality test for coating and potting materials of (power) electronic devices

Abstract

Cracks, penetration paths and adhesion weak spots in coating, potting or mold compounds for electronic assemblies result in a drastic shortening of the service life or the immediate break down. Especially in harsh environments like corrosive gases and humidity, corrosion as well as electric potential driven corrosion mechanisms like electrochemical migration (ECM) or the anodic migration phenomenon (AMP) under high voltage load are to be expected. Harmful gas testing was developed to check the robustness of these mostly polymer based systems. Disadvantages of these tests are complex test setups and long test durations.Addressing these drawbacks, this article presents a HAST quality test using iodine vapour. The test represents a quick alternative to characterize coating and potting robustness on (power) electronic assemblies against harmful gases and humidity. The comparison of the iodine vapour test (IVT) with conventional tests like mixed flowing gas testing (MFG) or the Flower of Sulfur test (FoS) shows that comparable results are obtained but with a significant shorting of testing time in case of IVT. In addition to these results, studies on the development of iodine vapour and humidity temperature over time in dependence of various test parameters as well as case studies are discussed.