ALBUQUERQUE, N.M. — Low-residue soldering processes with results confirmed by a government-industry task force managed by Sandia National Laboratories are saving the electronics industry time and money while reducing pollution.
Texas Instruments reports that since it received permission to use low-residue soldering for work done under more than 60 military contracts, it has reduced its materials processing costs for printed circuit boards by 96 percent. Texas Instruments was one of nine companies and military organizations that collaborated with the U.S. Department of Energy in the task force evaluation. The task force was organized by Sandia, a DOE multiprogram national laboratory.
Conventional processes for soldering printed wiring boards use an activated rosin-based flux prior to soldering to remove oxidation. Oxidation also is prevented by doing the soldering in a sealed nitrogen chamber. The rosin-based flux leaves a tacky residue that previously was removed with ozone-depleting chlorofluorocarbon (CFC) solvents. It has been estimated that solvents used to clean electronic equipment accounted for 24 percent of the consumption of CFCs in the United States.
Low-residue processes eliminate the need for these CFC cleaning solvents by using a mild organic acid as the fluxing agent. These organic agents, such as the common food additive adipic acid, leave little residue and require no cleaning.
When the Low-Residue Soldering Task Force was organized in 1993, low-residue processes were being used for commercial applications, but the Department of Defense required that use of the low-residue processes to manufacture military equipment be negotiated on a contract-by-contract basis. The task force was charged with evaluating these processes for general use in manufacturing military electronic components.
Sandia researcher Ron Iman chaired the task force, which consisted of 17 core members and a team of more than 100 people from 17 companies, three military services, and 12 laboratories and technical centers.
The task force tested low-residue processes at four manufacturing sites — Texas Instruments, Hughes Electronics, Alliant Techsystems, and AlliedSignal’s Kansas City Division. Each company used low-residue processes to produce 80 test printed wiring boards. After extensive testing, the task force concluded that these boards were as good as those manufactured by using rosin flux.
For confirming the value of the low-residue soldering processes, the task force was recognized with the U.S. Environmental Protection Agency’s 1995 Stratospheric Ozone Protection Award. Stephen O. Anderson, deputy director of the EPA’s Stratospheric Protection Division, called the task force’s findings “one of the most important soldering reports of the decade.”
Besides Sandia and the four companies, other organizations participating in the task force were the Naval Air Warfare Centers in China Lake, Calif., and Indianapolis, Ind.; Army Missile Command in Huntsville, Ala; the Air Force Materiel Command at Wright-Patterson Air Force Base, and the Electronics Manufacturing Productivity Facility.
Jeff Koon, a Texas Instruments process engineer who served on the task force, says Texas Instruments is now using a low- residue process in its production facility in McKinney, Texas. Using the process is saving more than $300,000 annually in materials costs, Koon says. It also is simpler to use and saves time in the production process.
Koon says the low-residue process is friendlier to the environment in several ways. It eliminates the need for CFCs and other noxious cleaning materials, and it significantly reduces the amount of lead dross produced during the manufacturing process.
Sandia has been collaborating with industry in researching environmentally friendly soldering processes for several years. Iman says the task force built upon this research and research by other organizations in evaluating the low-residue processes.