A Comparative Analysis of Lead Free Materials and Processes Using Design of Experiment Techniques
Lead Free Reliability Test Results
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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.