ELECTRONICS Lead-free future
Purchasing the latest electronic gadget inevitably means increasing the amount of electrical waste produced as the old ones are discarded. And the small individual lead content of each piece of equipment adds up to a big problem, which a researcher at the University of Oslo believes he may be on the way to solving
ILLUSTRATION: INGRID VEE/UIO
The sketch above shows how ALD technology works, here for the deposition of Al2O3. A molecule (trimethylaluminium) carrying aluminium is introduced into a reaction chamber and saturates the surface. Excess trimethylaluminium is removed from the chamber, before water is introduced and reacts in the same way. The process is repeated until the desired thickness is achieved
D
espite the advent of lead-free soldering techniques,most smartphones and other electrical or electronic products still contain small amounts of the toxic heavy metal lead.While this doesn’t sound like a
big problemon its own, when there aremany billions of such products, either in daily use or gone astray, the totalmounts up to a very large sum. The environmental authorities in the EU/EEA,
the USA and several other countries, have agreed to limit the use of lead in electrical and electronic equipment. Productsmust contain nomore than 0.1 per cent by weight of lead in order to be approved for CEmarking, according to current regulations (though there are exceptions, especially when there are no alternativematerials to be found). “In practice, it is not possible to limit or stop the
use of lead in such products if you don’t have other materials that can deliver the same benefits without being significantlymore expensive,” says researcher
46 /// Environmental Engineering /// August 2017
HenrikHovde Sønsteby. “Therefore, at the Department of Chemistry at the University of Oslo (UiO), we are trying to develop newmaterials that can replace the lead-containingmaterials.” Sønsteby is basing his work onmaking thin films
of amaterial that has the potential to replace lead in electrical and electronic products. Thematerial contains sodium, potassiumand oxygen in addition to themetal niobium, and has no known harmful environmental effects. “Strictly speaking, thematerial isn’t completely
new, but it has been difficult to produce it in a form that can be used in applications. But now we have solved this problemby using a technique called atomic layer deposition (ALD).We are now able to make thin films with potassiumand sodiumas important ingredients, which is something nobody else has been able to do earlier,” Sønsteby explains. The background for Sønsteby’s research is that we are buying evermore electrical and electronic
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