Prof. Pecht's New Article Available Free for Limited Time
Prof. Pecht and Bhanu Sood, former CALCE Test Services and Failure Analysis Laboratory director, have co-authored a new article “The effect of epoxy/glass interfaces on CAF failures in printed circuit boards,” which is now available online for free here until May 22 with Elsevier Press. No sign up, registration, or fees are required to access this article.
Bhanu Sood currently serves as commodity risk assessment engineer for microelectronics packaging and circuit boards with the NASA Goddard Space Flight Center in Greenbelt, Maryland. Sood spent more than 10 years at the University of Maryland and CALCE—working on aerospace, automotive, avionics, medical devices, and telecommunications industry-related failure analysis and reliability assessment.
The article addresses reductions in printed circuit board line spacing and via diameters and the increased density of vias with higher aspect ratios are making electronic products increasingly more susceptible to material and manufacturing defects. One failure mechanism of particular concern is conductive anodic filament (CAF) formation, which typically occurs in two steps: degradation of the resin/glass fiber bond followed by an electrochemical reaction. Bond degradation provides a path along which electrodeposition occurs due to electrochemical reactions. The path can result from poor glass treatment, from the hydrolysis of the silane glass finish, or from mechanical stresses. Once a path is formed, an aqueous layer, which enables the electrochemical reactions to take place, can develop through the adsorption, absorption, and capillary action of moisture at the resin/fiber interface. This paper describes the concerns with CAF and the methods used for analyzing low-resistance failures. A case study is then given which highlights problems that arose on a commercial circuit board material used by a major telecommunications provider.
Please follow this link for the full article as made available, for free, by the publisher.
Published April 4, 2018