Design of accelerated corrosion tests for electronic components in automotive applications

Two new accelerated laboratory corrosion tests for electronic components in automotive applications have been developed, based on the use of metallic copper as a meter for corrosivity. The accelerated tests are designed so that they reproduce the same kind of corrosion effects as observed with exposure of copper in real vehicle environments. The test cycle that best simulates the corrosion characteristics of an engine compartment is composed of the following steps: a) exposure to neutral salt spray for 2 h; b) drying at 23°C and 50% RH for 22 h; c) exposure to a test atmosphere of 1.5 ppm NO₂ and 0.5 ppm SO₂ at 25°C and 95% RH for five days; d) drying at 23°C and 50% RH for one day. The predominating corrosion products of copper, formed both during service exposure and in the accelerated test, are Cu₂O and Cu₂Cl(OH)₃, with a small amount of sulphur-containing corrosion products in the form of sulphates. In terms of corrosivity of copper, a test duration of six weeks corresponds to 7.5 years of exposure in the reference engine compartment selected for this study. The test cycle designed for the passenger compartment contains the steps: a) exposure for five days to a test atmosphere of 10 ppm NO₂ and 95% RH at 35°C, followed by b) drying at 23°C and 50% RH for two days. In this case, Cu₂O is the predominating corrosion product. In terms of corrosivity of copper, a test duration of four weeks corresponds to 7.5 years of exposure in the reference passenger compartment of this study