Pan Pacific Symposium Conference Proceedings


Authors: Sammy Shina, Ph.D., et al.
Company: University of Massachusetts
Date Published: 1/26/2010   Conference: Pan Pacific Symposium

Abstract: The New England Lead-free Electronics Consortium is a collaborative effort of New England companies spanning the electronics supply chain, created by the University of Massachusetts Lowell in 1999 and sponsored by the Toxics Use Reduction Institute and the U.S. EPA. The consortium has completed and published the results of three phases of manufacturing and testing of lead-free Printed Wiring Boards (PWBs) with the goal of achieving zero-defect lead-free soldering processes with comparable or superior reliability to that of leaded solder processes.

In this fourth phase of testing, which began in 2007, several simulated conditions of assembly and rework processes were evaluated in a matrix of multiple levels of components, PWB lead free surface finishes and solders, and compared to a baseline of leaded equivalent materials and processes. Both Through Hole (THT) and Surface Mount (SMT) Technologies were evaluated.

All quality and reliability testing was performed with industry standard methodologies, using specially trained production inspectors for the quality evaluation, and extreme thermal cycling and vibrations for reliability testing.

Our results indicate that with proper selection of currently available (2009) materials and finishes and careful control of the assembly processes, successful lead free assembly and rework can be achieved. Comparison of different strategies for rework, and recommendations for least copper dissolution for THT technology processes are discussed in chapter 6 of a book [1] published by the authors. Reliability testing showed inflection points for leaded versus lead free reliability that is currently being investigated through means detailed later in this paper.

Key words: Lead Free, Visual Inspection, Rework, Reliability testing, Thermal Cycling, Design of Experiments

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