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3.371 Fall 2002 Stephanie Dalquist Brief Proposal The electronics industry, heavy in waste and toxic substances, has been hit particularly hard by efforts to "green" the industry by removing lead from the manufacturing cycle. Known health hazards and bioaccumulation problems of lead have led the electronics industry to focus on the development of lead-free solders for use in printed wiring boards, where for years tin-lead solders have been the standard. Although years of research have led to the wide-spread availability of lead-free solders, the question remains as to whether the life cycle of lead-free solders is actually more environmentally friendly than that of traditional solder. This paper attempts to address these issues, especially with relation to temperature issues in the processing and use stages, and recycling at end-of-life. Outline I. Introduction II. Traditional solder A. Content 1. Lead-tin B. Characteristics 2. Different % qualities, uses III. Lead-free motivations A. Problems 1. Health 2. End-of-use: landfilling, burning bad B. Regulations 1. European WEEE Directive C. Cost D. Competition 1. Consumer perception IV. Lead-free alternatives A. Content 1. Systems B. Characteristics C. Problems 1. Process related a. Higher process temperature i. Different substrates required ii. More energy intensive 2. Life cycle problems a. Use i. Thermal fatigue ii. Metal migration b. Recycling & Take-back i. Contaminant ii. Metal migration 3. Other V. Solder alternatives VI. Conclusions References Bauer, B. and Grusd, A. “Lead Free: It’s about time and a little bit of temperature.” US Tech, June 2000. Biocca, P. “Global Update on Lead-free Solders.” Proceedings of Surface Mount International Conference. pp. 705-709. San Jose, CA, 1998. Eagar, T.W. "Typical Chemical Composition Limits of Lead-Tin Solders." 1998. Grusd, A. “Lead Free Solders in Electronics.” SMI97, p. 648-661. Hampshire, W.B. “The Search for Lead-Free Solders.” Proceedings of Surface Mount International Conference. pp. 729-736. San Jose, CA, 1992. Harrison, M. and Vincent, J. “Improved design life and environmentally aware manufacturing of electronic assemblies by lead-free soldering.” Available for download at http://www.lead-free.org/research/index.html Hwang, J.S. “Overview of Lead-Free Solders for Electronics & Microelectronics.” Proceedings of Surface Mount International Conference. pp. 405-421. San Jose, CA, 1992. Kwoka, M.A. and Foster, D.M. “Lead Finish Comparison of Lead-Free Solders versus Eutectic Solder.” Proceedings of Surface Mount International Conference. pp. 433-436. San Jose, CA, 1994. Nimmo, K. “Review of current Issues in Lead-Free Soldering.” Proceedings of Surface Mount International Conference. pp. 467-475. San Jose, CA, 1997. Richards B.P. and Levoguer, C.L. et al. “An Analysis of the Current Status of Lead-Free Soldering.” UK Department of Trade and Industry Report. May, 1999. Richards B.P. and Levoguer, C.L. et al. “An Analysis of the Current Status of Lead-Free Soldering: One Year On.” UK Department of Trade and Industry Report. May, 2000. Seelig, K. “Understanding lead-free alloys.” SMT Magazine. November, 1997. Smith, E. and Swanger, L.K. “Lead-free solders – a push in the wrong direction?” IPC Printed Cicuits Expo. March, 1999. Stuart, J.A. and Turbini, L. “Towards Quantifying the Effect of Lead Legislation on Electronic Product and Process Design.” IPC High Density Interconnections Conference. Arlington, VA, 1997. Socolowski, Norbert. “Lead free alloys and limitations for surface mount assembly.” Proceedings of Surface Mount International. pp. 477-480. San Jose, CA, 1995. Thwaites, C.J. “Soldering Technology - a decade of developments.” International Metals Reviews, 1984, Vol. 29, No,2, p. 45-74. Vianco, P.T. “Development of alternatives to lead-bearing solders.” Proceedings of Surface Mount International. pp. 725-731. San Jose, CA, 1993. Vianco, P., Artaki, J., et al. "Assembly Feasibility and Reliability Studies of Surface Mount Boards Manufactured with Lead-free Solders.” Proceedings of Surface Mount International Conference. pp. 437-448. San Jose, CA, 1994.
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