Conductive Anodic Filament (CAF) Performance Of PWB Materials Before And After Pb-Free Reflow
Authors: Joe Smetana, Kim Morton, and Thilo Sack Company: Alcatel-Lucent, Viasystems, and Celestica Date Published: 10/13/2013
Abstract: As a follow-up to previous work published in 2011, the High Density Packaging Users Group (HDPUG) consortium evaluated an additional 12 materials in two constructions each for hole-wall to hole-wall conductive anodic filament (CAF) performance. The materials tested include two high Tg phenolic FR4 materials, six halogen free FR4 materials, some of which might also be considered mid-level high speed materials, and four high speed materials. The materials are tested both as built and after Pb-free Reflow at 6X 260°C. Data is presented showing the CAF performance including the impact of reflow, the impact of glass styles on the materials CAF performance and extensive failure analysis. Failure analysis cross-sections are shown that explain the reason for the CAF improvement in many materials after reflow that was first identified in the prior work. Additional data is shown that confirms the 106 glass effect previously identified. One newly identified trend is the generally excellent performance of the halogen free materials in CAF testing, which suggests excellent wetting and bonding of these resin systems to the glass fibers.