High temperature lead-free solders. (News Briefs).Several industries have identified needs for solders that perform reliably at ever-higher temperatures, temperatures which approach the melting point melting point, temperature at which a substance changes its state from solid to liquid. Under standard atmospheric pressure different pure crystalline solids will each melt at a different specific temperature; thus melting point is a characteristic of a substance and of the industry-standard tin-lead eutectic alloy eu·tec·tic alloy n. An alloy that is generally brittle, easily melted, and subject to tarnish and corrosion, used primarily in dental solders. ([T.sub.m] = 183[degrees]C). For instance, automotive under-the-hood microelectronics are subject to higher ambient temperatures due to low hood profiles (less air circulation) and the need to place assemblies, such as engine control modules, near the point of application to reduce wiring harnesses. Such harsh environment applications require solders with melting points higher than that of tin-lead eutectic in order to achieve the required reliability. In addition, recent legislative and marketing pressures in Europe and Japan have pushed U.S. manufacturers to pursue lead-free solders for all microelectronics applications, leading to the double challenge of developing high temperature, Pb-free solders. This year the National Center for Manufacturing Sciences (NCMS NCMS National Center for Manufacturing Sciences NCMS National Classification Management Society NCMS National Compliance Management Services, Inc. NCMS North Carolina Masters Swimming NCMS North Canton Middle School (North Canton, OH) ) completed the 4 year High Temperature Fatigue Resistant Solder Project with the assistance of NIST (National Institute of Standards & Technology, Washington, DC, www.nist.gov) The standards-defining agency of the U.S. government, formerly the National Bureau of Standards. It is one of three agencies that fall under the Technology Administration (www.technology. . The goal of the project was to determine whether highly reliable, non-toxic, cost-effective substitutes could be found for industry-standard high lead and Sn-Ag eutectic solders in harsh environments. NIST played a leadership role in this research project, chairing the Alloy Task Group and providing definitive, timely phase diagram phase diagram, graph that shows the relation between the solid, liquid, and gaseous states of a substance (see states of matter) as a function of the temperature and pressure. data and critical analyses needed for evaluating candidate solders. NIST also coordinated the final analysis of the data, the determination of conclusions and recommendations, and the writing of the NCMS final report. Six lead-free solder compositions were identified that exhibit fatigue performance during cycling up to 160[degrees]C of a wide range of surface mount components which is superior to the industry standard eutectic Sn-Ag alloy. In addition, seven lead-free alloys cycled with ball grid array “BGA” redirects here. For other uses, see BGA (disambiguation). A ball grid array (BGA) is a type of surface-mount packaging used for integrated circuits. packages through 40[degrees]C to 125[degrees]C strongly outperforming Sn-Pb eutectic solder. The High Temperature Fatigue Resistant Solder Project was summarized in an invited article in Advanced Materials and Processes, April 2001, written by NIST staff. In addition, a technical paper presented by NIST was selected as one of the five best papers out of 58 presented at the TMS TMS Transcranial Magnetic Stimulation (alternative medicine for depression) TMS Test Match Special (sports - cricket) TMS Texas Motor Speedway TMS Transportation Management System TMS Toyota Motor Sales 2001 Annual Meeting Symposium on Recent Progress in Pb-Free Solders and Soldering Technologies. CONTACT: Frank Gayle, (301) 975-6161; frank.gayle@nist.gov. |
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