The minimization of risks and impacts to the environment associated with the treatment and disposal of end-of-life electronic and electrical equipment is certainly part of that challenge. The European Union concern was expressed in the directive that has become known as WEEE. Waste Disposal Design for the environment (DfE) is a great start on the answer to the mounting waste disposal problem. The current lead/bromine frenzy began with a draft document from the European Union Commission, Directive on Waste from Electrical and Electronic Equipment - the famous WEEE, mentioned above. The 1998 second draft absolutely banned lead in solder and bromine in epoxy. The fourth draft, recently issued, has postponed those absolute bans. The U.S. Mission to the European Union has proposed a new guiding principal: Design for the Environment, along with "horizontal" consideration of each potential source of pollution, instead of absolute bans from the top. It's in tune with the main thrust of the WEEE directive on recycling. The lead and bromine bans were always peripheral to this main thrust of the WEEE Draft, which became greatly exaggerated as the news traveled across the Atlantic. A research project1 at Brunel University in the UK quantifies the big picture for Europe, and by extension for the U.S.
Electronics contribution to total waste is relatively small; it's also a very small portion of potentially hazardous waste. Tables 1 and 2, courtesy of Dr. Malcolm Warwick, offer some revealing insights.
Solder Lead in solder, whether the common 63% tin/37% lead <183o eutectic and alternative alloys have been extensively discussed in the IPC Forum leadfree@ipc.org and in many other forums. Summarizing: • Lead in paint from building demolition debris has been going into landfills for over 75 years. The first few inches of soil in the U.S. contain lead from gasoline. • Between the late 70s and the late 80s, the average level of lead in the blood of American children declined 75%. • The metal alternatives to lead in solder are also toxic at some level2. • The compounds of lead, especially the most common, lead oxide, have very low solubility, almost eliminating the risk to water supplies. • Establishing new market channels, standardizing, performing all the required reliability and stress tests for alternative solders, coping with all the compatibility problems and learning how to use them with comparable yield losses constitutes a multi-billion dollar levy on the world electronics industry. • Most eutectic temperatures for alternative no-lead alloys are over 30 (higher than for 63/37. This subjects semiconductors and other components to unknown stress effects and causes more energy expenditure in manufacturing processes. • Most alternatives exhibit more voids and lower wettability. Putting it all together, it's a reductio ad absurdum argument against lead in solder. Start with the correct thesis that lead is bad, then examine its use in solder, its essential role in a nearly $1 trillion electronics industry. There is only one possible conclusion: lead in solder is the best option there is. Bromine Bromine in epoxy resin for printed circuit fire retardation is similarly a victim of guilt by association. Some brominated compound fire retardant additives do release poisonous fumes, such as those commonly used in polyurethane foams. But the TBBPA used in printed circuits reacts with the epoxy and becomes part of the polymer backbone. Its combustion products are not toxic. At the PC EXPO in San Diego, Calif., in April, several informative papers illuminated the issues. Marcia Hardy of Albemarle presented an extremely well researched and documented paper that also discussed the burning of printed circuits along with other waste. She may have exonerated bromine, but certainly raised questions about chlorine from non-electronic sources. Another paper, this one delivered by Marc Hein of Isola Laminates, a user of TBBA, confirmed the main thesis of non-toxicity along with cost-effectiveness.
Bottom Line Some good has come from the enormous effort to replace lead in solder and bromine in epoxy. But the exercise of going to the conceptual brink of necessity to actually do it has been traumatic for most of the electronics industry. But then, that's what it takes, sometimes, to see things in a new light. Some worthwhile material research has resulted in important new materials. For example, Hitachi Chemical, Toshiba Chemical and Isola have developed new laminates that also happen to be halogen-free. And to quote Dr. Jenny Hwang, "During the course of lead-free solder R&D, fundamentals in solder materials have advanced." Some of the alternatives may well turn out to be useful for specific applications. Furthermore, recycling has moved to the center of our collective consciousness.
References
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