Disassembly using bioscience

Citation

(2000), "Disassembly using bioscience", Circuit World, Vol. 26 No. 1. https://doi.org/10.1108/cw.2000.21726aad.009

Disassembly using bioscience

Disassembly using bioscience

Keywords Environmentally friendly, Printed circuit boards, Biodegradability

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 under way into making a biodegradable 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.

Makers of electrical and electronic goods are presently bracing themselves for the introduction of EU directives (e.g. WEEE) relating to the elimination of materials such as lead and demands for up to at least 90 per cent recyclability.

Dismantling redundant goods using biodigestion could be the first step in satisfying these recycling demands. If circuit board substrate 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-usable 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 the new biodegradable circuit boards include proteins, for example casein and plant extensins, and carbohydrates, for example cellulosics and chitin. These materials have the potential to 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. The team has also addressed this area.

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.

The principle of designing for disassembly is a relatively new one for industry and for the participating organisations. TWI has spent half a century trying to make the strongest joint last forever. This knowledge and experience are now being applied to make things fall apart in a controlled manner once their life is over.

TWI and BTTG are currently looking for more collaborating partners to participate in this project. Please contact Roger Wise at TWI. Tel: +44 (0) 1223 891162; or Brian McCarthy at BTTG on Tel: +44 (0) 161 4458141 to learn more about this exciting opportunity.