Moisture resistance of thin film electrical insulation A comparison of test methods

Abstract

A wide variety of tests purports to show the ability of magnet wire to stand up to water. The results show that the contribution of hydrolytic attack on the polymer itself is insignificant in salt water bath failures. Samples with similar dielectric strength and resistivity give vastly different results in salt water. Failures in water immersion tests occur, not because of the attack of water, but because of its availability as a conductor. This conductor seeks out flaws and weak spots in the film, shorting them to ground or to other flaws.