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Phase III - Reliability Testing Results of Surface Mounted Lead Free Soldering Materials and Processes, 2005

  Article published in SMT magazine related to TURI's Lead-Free work. The world-wide movement to phase out lead from electronic products presents many challenges for companies throughout the electronics supply chain. The University of Massachusetts at Lowell has brought together many Massachusetts/New England 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. Following 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 was made and tested in 2003. Three lead-free solder pastes based on Sn/Ag/Cu alloys were reflowed using either air or nitrogen with five PWB surface finishes, four component types with two types of component finish. Visual inspection and pull-testing were performed and published as completed in APEX, SMTI and IEEE conferences. This paper summarizes the testing results and introduces further research plans in volume manufacturing of lead free PWBs for the phase III testing sponsored by the EPA. Download PDF file (388.79 kB)

Developing and Analyzing Lead-Free Soldering Processes for Printed Wiring Boards. 2000.

  TURI Technical Report No. 52. Researchers on this project formed an industry-led "UMASS Lead-Free Consortium" (the Consortium) of local and national companies to evaluate various emerging alternatives to lead-based solders and finishes. The consortium members donated expertise, time, materials and equipment to this project. The various alternatives to lead-bearing materials, surface finishes and manufacturing processes were evaluated as factors in a set of designed experiments, and compared the results to a baseline of standard leaded processes and materials, using the quality characteristics of visual, mechanical and thermal testing criteria. The Manufacturing Research Laboratory facilities at UMASS Lowell were utilized to test and analyze the performance of alternatives based on the principles of Design of Experiments. Results were analyzed using statistical techniques resulting in determining whether a particular factor was significant to the quality characteristic being measured. A theoretical percent contribution to the total quality characteristic was calculated for significant factors. Download PDF file (307.96 kB)

Arsine Source Replacement for the Growth of Gallium Arsenide via MOCVD. 1993.

  TURI Technical Report No. 8. This feasibilty study involves the systematic evaluation of arsenic containing reagents that could potentially replace arsine gas from the process and manufacturing of microwave semiconductor diodes. The reagent would act as an input substitution in the Semiconductor Materials Laboratory at the Burlington Facility of M/A-COM. Download PDF file (635.29 kB)

Evaluation and Implementation of No-Clean Solder for Surface Mount Technology. 1997

  TURI Technical Report No. 40. This study addresses the implementation of no-clean solder pastes for a small contract manufacturing situation. The issues regarding the cleaning of electronics are discussed as well as the mechanics of the no-clean materials involved. A general methodology for implementation was generated along with a research implementation methodology. Following the research implementation methodology, materials were qualified against industry standards for acceptability. Matrix experiment methods were utilized to model the manufacturing equipment at an actual small contract assembly house in Massachusetts. Results led to the statistical examination of their equipment and yielded the important factors involved with each piece of equipment. Optimization techniques were utilized to recommend the best settings for the manufacturing equipment, and the settings found were tested on a real world product of the contract assembler. The results obtained were excellent and the customer has subsequently changed the requirements of that particular product to be assembled exclusively using no-clean solder pastes. An economic analysis was also completed to determine the cost savings that would be realized if conversion was completed at the contract assembly house. Download PDF file (5.30 MB)

Cupric Chloride Etch Regeneration. 1997

  TURI Technical Report No. 45. Tri-Star Technologies, located in Methuen, Massachusetts, has one of the world's largest facilities offering in-house printed circuit board design, fabrication and assembly, from prototype through production volumes. Their state-of-the-art, 120,000 square foot facility provides a "one-stop shop" for a full range of on-site services and expertise, providing the customer with the advantage needed in today's competitive marketplace. In its continuous efforts to implement toxics use reduction (TUR) and pollution prevention, Tri-Star Technologies evaluated, adopted and installed an electrolytic regeneration technology to reduce the amount of spent cupric chloride etchant generated. By making electrolytic regeneration an integral part of the process, Tri-Star is able to reuse the etchant and sell the recovered copper. This technology replaces the chemical regeneration system previously used, while reducing costs, worker exposure to hazardous materials, and environmental impact. TriStar has achieved many prior successes with TUR, including an 86%reduction in volatile organic compounds through the addition of a double-sided solder mask screening unit, a reduction in sulfuric acid use on the auto pattern plate line, and the elimination of bath contamination on the copper deposition line. Download PDF file (402.63 kB)