Dielectric Material Characterization for the PCB Pad Cratering Resistance
Authors: Cheng-Chih Chen, Jeffrey Chang-Bing Lee, Dem Lee, Cherie Chen Company: iST- Integrated Service Technology Date Published: 8/28/2017
Abstract: In the study, the cold ball pull test was adopted to determine the resistance to pad cratering of 6 different materials including: high Tg non-filled Phenolic FR4s, high Tg halogen free FR4s and high speed materials groups. The test coupons were designed with a 16 mil nominal pad size onto which a 20 mil SnAgCu ball was attached for pulling. Each material had 5 coupons with 50 pull locations populated to generate data for 250 pulls for the following statistical analysis. The pull strength values obtained can differentiate performance of various materials. Afterward, failure locations were observed by optical microscope from the pad location surface and through cross section to determine failure mode.. We conclude the method is suitable to simulate field failure mode and sufficiently sensitive to differentiate performance of various dielectric materials to resist PCB pad cratering.