Conductive filament formation in printed circuit boards: effects of reflow conditions and flame retardants

  • Bhanu Sood
  • Michael Pecht


Conductive filament formation, a major cause of failures in printed circuit boards, is an electrochemical process that involves the transport of a metal through or across a nonmetallic medium under the influence of an applied electric field. With an increasing potential to market “green” electronics, environmental and health legislations, and the advent of lead-free and halogen-free initiatives, newer types of printed circuit board materials are being exposed to ever higher temperatures during solder assembly. The higher temperatures can weaken the glass-fiber bonding, thus enhancing conductive filament formation. The effects of the inclusion of halogen-free flame retardants on conductive filament formation in printed circuit boards are not completely understood. Previous studies, along with analysis and examinations conducted on printed circuit boards with failure sites that were due to conductive filament formation, have shown that the conductive path is typically formed along the delaminated fiber glass and epoxy resin interfaces. This paper is a result of a year-long study on the effects of reflow temperatures, halogen-free flame retardants, glass reinforcement weave style, and conductor spacing on times to failure due to conductive filament formation.


PCBs Print Circuit Board Hollow Fiber Conductive Filament Path Formation 
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The authors would like to thank the more than 100 companies and organizations that support research activities at the Center for Advanced Life Cycle Engineering at the University of Maryland annually.


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Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  1. 1.Center for Advanced Life Cycle Engineering (CALCE)University of MarylandCollege ParkUSA
  2. 2.Center for Advanced Life Cycle Engineering (CALCE)University of MarylandCollege ParkUSA

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