SMTA International Conference Proceedings


A COMPARATIVE ANALYSIS OF LEAD FREE MATERIALS AND PROCESSES USING DESIGN OF EXPERIMENTS TECHNIQUES

Author: Sammy Shina et al.
Company: University of Massachusetts
Date Published: 9/21/2003   Conference: SMTA International


Abstract: The worldwide movement to phase out lead from electronic products presents challenges for companies throughout the electronics supply chain. The University of Massachusetts Lowell has brought together eight Massachusetts firms to collaborate on the manufacture and testing of lead-free printed wiring boards (PWBs). The results of the first set of experiments, published in 2001, showed that zero-defect soldering is achievable with lead-free materials. After thermal cycling, the PWBs were visually inspected and the leads were pull tested for reliability analysis. They compared favorably to a baseline of lead soldered PWBs.

A follow-on design of experiments was created in 2002 and a second set of test PWBs with a wide variety of components was manufactured. Several solder pastes based on Sn/Ag/Cu were used with a variety of PWB surface finishes, and reflowed using either air or nitrogen. Visual inspection results have been completed and published, This paper discusses the results of the pull-testing phase of the project. Future work to be completed includes thermal cycling and subsequent pull testing. Results will be published in future papers at electronics conferences.

Key words: lead-free, design of experiments, PWB soldering, solder joint reliability, interchangeability of leaded and lead free components.



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