Connector reliability testing using salt spray

In this study a salt spray test was used to compare the reliability of electrical connectors from two different manufacturers. The difference between connectors was in the coating materials of the connector pins. Manufacturer A used tin for the outermost coating layer, nickel for the second layer, and brass for the pin material. Manufacturer B also used tin for the outermost coating and brass for the pin material, but copper for the second coating layer. The test was executed according to SFS-ISO standard. The connectors were placed in a salt spray test chamber for 2000 hours. The test consisted salt spray operation modes of 300 and 1100 hours and a period of 600 hours when the chamber was halted between the salt spray operation modes. During testing the connectors were measured using continuous real-time measurements. A 10% increase in the measured voltage was used as a failure criterion. Significant differences between the manufacturers could be found related to materials during testing. Cross sections were analyzed by means of a microscope and a scanning electron microscope (SEM). An elementary analysis was performed to determine the material changes. The pin itself is made of brass, which contains copper and zinc. In the elementary analysis of the untested connector it was observed that the brass contained about 65 wt% of copper and 35 wt% of zinc. The elementary analysis of the damaged connector revealed that the damaged area contained 95 wt% of copper and 5 wt% of zinc. The disappearance of zinc in the damaged connectors can be explained by dezincification.