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Written by Mike Buetow and Chelsey Drysdale   
Tuesday, 01 October 2013 04:50

Assembly Materials

“Evaluation of Solder Pastes for High Reliability Applications”
Authors: Scott Anson, Ph.D., Michael McLaughlin, and Abner Argueta; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
Abstract: This study examined SnPb37 alloy with SnPb37 components and with SnAg3.0Cu0.5 (SAC 305) components for mixed-alloy reflow. Water-soluble and no-clean chemistries were evaluated. A design of experiments approach was employed to examine solder balling and slump resistance. Additional experiments examined print quality utilizing automated solder paste inspection (SPI) in terms of bridge resistance, CSP and 0201 insufficient resistance, and response to a 45-minute print pause. Assemblies were also built to check for yield, joint quality and voiding. The result is a holistic approach to solder paste testing that includes weighting of numerous factors to assess solder paste performance and robustness. (SMTA International, October 2013)

“Pb-free & Halogen-free Solder for High Reliability Applications”
Author: Ian Wilding; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
Abstract: The performance of a Pb-free solder alloy specifically designed for high-temperature thermal cycling is discussed. Also documented: challenges and breakthroughs in developing halogen-free or “zero halogen” solder fluxes compatible with the alloy. (SMTA International, October 2013)

PCB Reliability

“Conductive Anodic Filament (CAF) Performance of PWB Materials Before and After Pb-free Reflow”
Author: Joe Smetana, Kim Morton and Thilo Sack; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
Abstract: As a follow-up to previous work published in 2011, the High Density Packaging Users Group consortium evaluated an additional 12 materials in two constructions each for hole-wall to hole-wall conductive anodic filament performance. The materials tested include two high Tg phenolic FR4 materials, six halogen-free FR-4 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 show 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 explained the reason for the CAF improvement in many materials after reflow that was first identified in the prior work. The 106 glass effect previously identified was confirmed. 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 glass fibers. (SMTA International, October 2013)

This column provides abstracts from recent industry conferences and company white papers. Our goal is to provide an added opportunity for readers to keep abreast of technology and business trends.

Last Updated on Tuesday, 01 October 2013 18:43
 

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