Evaluation of the Anti-Sulfur Corrosion Capacity for Chip Resistor and Conformal Coating by Way of Flower-of-Sulfur (FoS) Methodology

IT equipment is prone to sulfur corrosion-related failures in data centers with high levels of atmospheric pollution and with high relative humidity levels commonly found in the fast-growing computer markets of Asia. The main atmospheric pollutants are sulfur-bearing gases and oxidizing gases such as ozone and nitrogen oxides. In general, there are two solutions to solve the threat of sulfur corrosion in the industry. Frist one is corrosive-gaseous contamination controlling in field environment. Second one is improved the robustness against sulfur corrosion of electronics hardware. However, gaseous contamination limits for the reliable operation of electronic equipment cannot be specified clearly in terms of the concentrations of gaseous contaminants in the air since the metal corrosion is a complex process. Therefore, it is very important to classify the robustness against sulfur corrosion of electronics hardware for high-end electronics hardware application, especially for datacenter, automotive and medical.In general, there are several methods to elevate the anti-sulfur corrosion capacity of electronics hardware, including noble metal and conformal coating application. For example the typical chip resistor can be replaced the silver electrode with a noble metal as anti-sulfur chip resistor. Besides, conformal coating is a system-level solution which can protect the board and component to prevent the sulfur corrosion occurrence. In this paper, the international standard of EIA-977 FoS test was adopted to evaluate the anti-sulfur corrosion capacity for chip resistor and conformal coating. EIA-977 FoS test is latest sulfur corrosion qualification for the electronic passive components exposure to atmospheric sulfur which was published in 2017. Several analytical methods were used in this work, including, high resolution 3D X-Ray Microscope (3D X-Ray), Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray spectroscopy (EDX). Finally, we can verify the anti-sulfur corrosion capacity for chip resistor and conformal coating by using the Flower-of-Sulfur (FoS) Methodology.