Hollow Fibers in Printed Circuit Boards Induce Reliability Degradation

Hollow Fibers in PCB, MCM-L, and PBGA Laminates May Induce Reliability Degradation A. Shukla, M. Pecht, J. Jordan, and K. Rogers CALCE Electronic Packaging Research Center University of Maryland, College Park, Maryland 20742 D. Jennings Collins Commercial Avionics Cedar Rapids, Iowa 52498

Abstract
The presence of hollow fibers in laminates used in printed circuit boards, multichip module laminated substrates, and plastic ball grid arrays has a potentially significant impact on reliability. Hollow fibers are vacuous glass filaments in E-glass laminate reinforcements and are seen as a reliability problem since they can provide paths for failure mechanisms such as conductive filament formation. This paper discusses the manufacture of woven fabric laminates and the cause of hollow fibers. Experiments conducted to assess the occurrence of hollow fibers in laminates are then presented along with the key reliability issues.