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Lasagne and chips?

Connect, no. 102, September/October 1999, p.3

Biodegradeable circuit boards


TWI has spent half a century trying to make the strongest joint last for ever. This knowledge and experience is now being applied to make things fall apart in a controlled manner once their life is over.

The quest for the ultimate environmentally friendly product could be just around the corner if plans to make electrical goods which biodigest can be fulfilled. Already investigations are underway into making a biodegradeable circuit board. The fundamental principle is that if electronic products include elements which are biodigestible, their disassembly becomes a far simpler matter than at present.

Dismantling redundant goods using biodigestion could be the first step in satisfying forthcoming EU recycling directives. If circuit board material, the substrate to which all active electrical circuitry is attached, could be made from a degradable material, detaching the components becomes a far simpler business.

TWI and BTTG (the British Textile Technology Group) have entered into a collaboration to develop this technology up to industrial demonstrator scale and have applied for a patent.

To illustrate the principle involved in the selection of a PCB material, consider uncooked culinary pasta. It has an inherent stiffness and shear strength to support light electrical components and conductor strip. When the assembly has reached the end of its usable life, immerse it in hot water - the pasta's strength properties disappear and the re-useable parts can be detached. Allowing the pasta to naturally decompose would form the final stage in the breakdown of the product. Of course pasta is not a serious candidate for this application but it demonstrates the principle. Actual candidate materials for biodegradeable circuit boards include proteins (casein and plant extensins) and carbohydrates (cellulosics and chitin) which potentially can perform as well as conventional glass/epoxy circuit boards. Performance characteristics to be assessed include mechanical strength, stiffness and dimensional stability as well as dielectric properties. In addition, it may be necessary to develop associated technologies to allow electrically conductive tracks to be fixed to the biodigestible boards and this area has also been addressed by the team.

It is envisaged that once designers have become familiar with the principles of biodigestion technology, designs of electrical goods could be changed radically to make dismantling and recycling easier.

The investigating team will also be examining the in-service stability of biodegradable boards so that future users can feel confident that the biodegradation process will only occur at the end of the component's life and not before.

TWI and BTTG are currently looking for more collaborating partners to participate in this project. Please contact Roger Wise at TWI (e-mail: ) or Brian McCarthy at BTTG (0161 4458141) to learn more about this exciting opportunity.

For more information please email: