Evaluation of the anti-corrosion capacity for various electronics by way of accelerated corrosion testing platform

Abstract

Severity levels of air pollutant rich in oxides, chlorides and sulfurs can cause severe corrosion on electronic equipment. Besides, high atmospheric concentrations of sulfur also can be found in wide variety of industries that use electronics. With the more and more severe environmental pollution, especially in regions with high pollution levels, the corrosion phenomenon will also directly or indirectly influence the reliability of electronics. In order to ensure the reliability requirement is enough even if the electronics in severe environment. Therefore, it is very important to evaluate the anti-corrosion capacity for high-end electronics, including datacenter, automotive and medical application. In general, there are two common-corrosive modes of electronic failure due to corrosion. The first one is copper sulfide, e.g. copper creep corrosion on printed circuit boards which is an electrical short failure. The second one is silver sulfide, e.g. silver termination in miniature surface-mounted components which is an electrical open failure. Guidelines from the International Society for Automation (ISA) standard 71.04–2013 and 2011 American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) Technical Committee (TC) 9.9 Whitepaper were used to classify the measured thickness of airborne contaminants into the various severity level rankings by using pure copper and silver coupon exposure. The effects of corrosion are measurable and may be a factor in determining electronic equipment reliability when the air quality is the severity level G2. Therefore, it is necessary to understand the corrosive level in field environment. And also to calibrate the accurate corrosive reaction rate in accelerated corrosion chamber for each test run. Because the sample loading and chamber setup will influence the corrosive reactive rate, even if the same test condition was carried out at test run. iST have developed and integrated an effective accelerated corrosion testing platform, including Flower of Sulfur (FoS), Mixed Flowing-Gas (MFG), Coulometric Reduction (CR) and Failure Analysis (FA). It could provide a rapid, cost-effective and accurate information for relevant material selection to prevent corrosion failure occurrence, even if simulate long-term exposure at in-field environment through accelerated corrosion chamber. In this paper, the accelerated corrosion testing platform was adopted to evaluate the anti-corrosion capacity for various electronic and material, including Printed Circuit Board/ Printed Circuit Board Assembly (PCB/PCBA), Resistor Chip (R-Chip), Light-Emitting Diode (LED) and Conformal Coating. Several analytical methods were used in this work, including, Optical Microscopy (OM), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray spectroscopy (EDX) and Coulometric Reduction (CR). Finally, we can verify anti-corrosion capacity by using the accelerated corrosion testing platform, and also improve their robustness against corrosion in future.