Though computer asset recovery facilities have processed more than 120 million pounds of scrap material from obsolete computers, the use of nearly indestructible epoxy adhesives around circuit board components, worth hundreds of dollars apiece, has meant that nearly 80% of printed circuit boards cannot be reused. Cornell’s new adhesive, Terpineol epoxy monomer (Alpha-Terp), seemingly indestructible at first, is designed to break down at 190°C, so that the glue can be dissolved with a common industrial solvent.

“The only other way to break an epoxy’s grip is to smash it with a hammer,” said John Jir-Shyr Chen, one of the researchers at Cornell’s College of Engineering. “And that’s kind of tough on those delicate components. If it proves to be cost effective, safe and can be widely adopted, this material should go a long way toward making computers 100% recyclable.”

In 1998, more than 20 million computers became obsolete and unwanted in America, according to a study by the National Safety Council. At that rate, by 2005, some 55 million computers a year could be discarded in landfills, say the Cornell researchers.

Alpha-terp’s performance has been studied with a variety of analysis techniques, including nuclear magnetic resonance spectroscopy, while applying more and more heat.

“Epoxy compounds in electronics applications have to be super tough because they serve so many functions,” explained Chen. “They must form a hermetic seal to isolate components and connections from the environment and prevent corrosion and contamination. They have to be an electrical insulator. And they have to offer stress relief and enhance the general resilience of the product. Part of that function is coefficient-of-internal-expansion management, because different materials that are located next to each other will expand or shrink at different rates as the product heats and cools.”

“This epoxy seems to have all the attributes for an environmentally sensitive design that calls for an adhesive that can be easily removed and cleaned up,” said Chen. “If this material is adopted in the manufacturing process of computers, their circuit boards will be a lot easier to disassemble for reuse and recycling.”

Funding for the epoxy study was provided by the Semiconductor Research Corporation and IBM.

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