Solder Dross Recycling: A Case Study

Estimated reading time: 5 minutes

By Simon Norman, EVS International

The world price of solder is at an all-time high, so reducing solder consumption therefore reducing incurred costs should be at the top of every electronics manufacturer's priorities list. On average, EMS companies throw away 75% of their solder as dross. One company worked with their equipment supplier to automate the solder dross recovery process in-house.

By automating the solder dross recovery from their wave soldering process, a company can reduce de-drossing time by up to 80% and solder purchases by up to 50%. Recycle, Reduce, Re-use is set to become as much an industry mantra as smaller, faster, cheaper, as issues such as energy and resource consumption and waste management are pushed to the fore. Contract manufacturer Kimball Electronics found that adhering to these new priorities can result in cost savings.

Kimball Electronics began as The Jasper Corporation in 1950, acquired in 1959 by W.W. Kimball Piano Co., and entering the electronics sector in 1961. In 1983, the company gained a major contract to build keyboards for personal computers and in the subsequent ten years shipped over 19 million units. In 1992, they began producing computer mice, producing over 50 million before the business was taken offshore. In 1985, the company began producing products for the automotive industry.Manufacturing has seen many changes since 1961, with energy output, resource consumption, and waste management integral to modern EMS. "As a company we had a high consumption of solder bars and I felt sure there must be a way in which we could reduce this," said Marla Wineinger, responsible for wave solder. "It is our responsibility to look at reducing costs wherever possible, but as an industry we must all look at reducing the world's resources that we use, too."

Kimball Electronics was putting the dross from their wave soldering machines into a 55-gallon drum and selling it to outside sources for recycling. "I wanted to look into whether it would be possible to deal with the solder dross more efficiently, to ultimately reduce our usage, but also to see whether this could be achieved by bringing the recycling process in-house," said Wineinger. "The process could not impact heavily on our day-to-day production cycle."

Along with the solder dross reduction equipment provider, Kimball evaluated its production and wave soldering processes. Companies which incorporate dross recycling equipment into their production process can expect up to an 80% reduction in de-drossing time and up to a 50% reduction in solder purchases, bringing return on investment (ROI) in the equipment to an average of a few months.

There are added benefits to recovering pure solder from solder dross, such as improvements in process and line productivity. With a cleaner wave pot, manufacturers will experience a significant reduction in shorts and bridging on the board, as well as reduced wave maintenance. The system will provide a consistent wave height and improved solder quality due to reduced oxidation, and users have the potential to dramatically reduce their consumption of nitrogen in the soldering process. Environmental standards to consider, such as ISO14001, are fast becoming mandatory in our industry, and gaining or retaining accreditation is helped significantly by recycling dross at the point of manufacture.

The ISO14001 standard, published in 1996, was pioneered by the British Standards Institute (BSI). It is designed to enable each individual business to create and monitor an environmental management system to suit their particular activity. Application of an environmental management system to ISO14001 will show practical business results in terms of increased efficiency and reduced costs, as well as environmental benefits for the whole community. ISO14001 improves operational efficiency and cost reduction in areas such as energy consumption, waste minimization and primary resource utilization.

By bringing dross recycling in-house with an automated process, Kimball would have an environmental management system with little impact on their routines and workload. The operator would be able to de-dross the wave then prepare for production while the equipment was performing its de-drossing cycle. Working in conjunction with Wineinger, the supplier decided that the most efficient system to match Kimball's needs would need to recover pure solder from both lead-based and lead-free solder dross. The system Kimball vetted was capable of handling up to 20 kg/44 lbs, with the capacity for single operation de-drossing of a large wave soldering machine. An integrated hopper allowed simpler, safer transfer of dross and would speed up Kimball Electronics' de-drossing by up to 50%.

Automated solder dross recovery equipment systems use a hopper to load hot dross, then recover solder into a solder tray in the form of ingots that can be placed back into the solder pots; it then deposits the spent dross automatically to a covered dross bin. Operator intervention is minimal, and processes are self-contained to avoid excessive handling of heavily lead-contaminated dross. Filtration systems are made for these systems that can eliminate smells and noxious fumes. Hopper extraction systems can prevent escape of fumes and dust that may be generated while loading. Chemicals, radiation, additives, or other noxious substances are kept out of the recycling process.

Safety in the workplace is paramount, not only for the operating procedure but also for routine maintenance and cleaning functions. Because of the nature of the process, extensive safety features must be built into solder dross recovery systems to protect against misuse. Ergonomics, simple instructions, and machine construction all contribute to a recovery process's safety.

In the last three years, Kimball Electronics introduced three systems at their U.S. plant and two in Mexico. "We can recover waste material from our wave solder process and return it to usable product on-site at the point of manufacture, so we have achieved what we set out to do," said Wineinger, adding that unexpected benefits include reducing the material going into the waste stream, reduced machine set-up time, and lower machine downtime. "We have reduced our administration and improved the working area, with no noxious fumes and a cleaner workshop floor and we have reduced our solder bar usage.

ConclusionThe high cost of solder frequently drives EMS providers to invest in capital equipment that can reduce solder consumption. Lead-free solder is at a 200 to 300% premium over lead solder, and lead-free adoption is spreading. The electronics industry is now switching on to the benefits of ISO14001, with more and more companies actively pursuing efficiency, effectiveness, and cost reduction in their manufacturing strategies.

Simon G. Norman, international director, EVS International, may be contacted at +44 (0) 8451 30 47 33; Fax: +44 (0) 8451 30 47 34; simon@evsinternational.com; www.solderrecovery.com.