We have studied the effects of chlorine dioxide fumigation on the reliability of electronic equipment using personal computers as examples of current commercial systems. Unit and subunit failure were objectively defined by standard commercial software. After the initial one-day exposures to the fumigation conditions, the systems were tested to assess impacts and retested monthly for six months. Cumulative failures of decontaminated systems were many times higher than unexposed systems and increased progressively for the harshest fumigation conditions. Failures occurred in electronic, mechanical, optoelectronic, and thermal subsystems. Failure mode and root-cause analyses were performed on a blind sample of systems. Corrosion of metals and degradation of organic materials were predominant causes of failure. Metal corrosion continued to progress well after the initial exposure.

Cu corrosion in mixed flowing gases (MFG) has been widely studied. However, most of these studies have been carried out using conditions which were designed for accelerated tests simulating North America and Western Europe. More and more equipment are being deployed to emerging markets such as Asia Pacific and China, Eastern Europe, and the Middle East, where they are subjected to much more corrosive environments than those typically seen in North America and Western Europe. There is a need to understand the corrosive conditions in the emerging markets and come up with an accelerated test for products to be deployed in those conditions. In this work, we investigated the corrosion products on test Cu coupons exposed to harsh conditions by a combination of several analytical techniques. This work allowed us to establish a procedure for quantifying corrosion products and led to insights about corrosion mechanisms for copper in highly corrosive environments. Results showed that the corrosion of copper in the highly corrosive MFG testing condition (containing H2S, SO2, Cl-2, and NO2) leads mainly to the formation of copper sulfide (Cu2S) at the exposed surface, with the presence of a thin, buried cuprous oxide (Cu2O) layer sandwiched between Cu2S and copper substrate. The thickness of the corrosion products increases linearly with the exposure time. (C) 2009 The Electrochemical Society. [DOI:10.1149/1.3258288] All rights reserved.

Pure copper samples were exposed in an environmental chamber for 2, 4, 7, 15, and 30 days at 90% relative humidity, 40 degrees C, and 4 ppm hydrogen sulfide (H2S). Samples were subsequently subjected to microscopy and microanalysis using different techniques: scanning electron microscopy, energy analysis dispersive X-ray spectroscopy, X-ray diffraction, focused ion beam (FIB), and secondary ion mass spectroscopy. The corrosion samples were cross sectioned and the different corrosion layers were imaged using FIB. After 30 days exposure the predominant corrosion products were copper sulfide (Cu2S) and cuprite (Cu2O). Once the Cu2S reached a minimum thickness, the rate of growth of the layer became parabolic due to the limiting Cu+ diffusion through a thickening film. As the layers reach a critical thickness (similar to 1000 nm) internal stresses and defects in the corrosion layer allow virtually free access of H2S and O to the underlying layers, consequently accelerating the film growth. (c) 2007 The Electrochemical Society.