CABLE MANAGEMENT
Zinc Whiskers – Bare-Faced Scaremongering? Chinese Whiskers By Paul Courson, UK Managing Director, Cablofil
The idea that there may be something ‘growing’ within the data centre that could potentially cause equipment failure or a short circuit is horrifying to data centre operators. When these growths are so microscopic that they are not only potentially hazardous but also largely invisible, the concept becomes even more unpalatable. In fact, this is not the stuff of data centre nightmares; it’s a phenomenon that was discovered as long ago as the 1940s! Zinc whiskers are tiny, conductive
Explaining the phenomenon of ‘Zinc Whiskers’ and exploring whether the risks that they present to contemporary data centres have been exaggerated.
filaments of zinc that can grow from any metal surfaces that have been electroplated with zinc to provide protection against corrosion. Typically only a few millimetres long (or less!) and a few microns (thousandths of a millimetre) in diameter, these microscopic monsters can conduct tens of milliamperes before melting and the fear is that if they manage to bridge tightly-spaced electrical conductors they can cause electrical shorts. Reportedly, these shorts are often intermittent, causing nuisance glitches that can be hard to identify. Sometimes, however,
zinc whiskers are also cited as the cause of system failures after a permanent short has occurred. The internet is awash with discussions
about the threat of zinc whiskers and concerns are growing about the risks within the data centre sector. However, very little actual research and testing has been done to ascertain what, if any, actual risk exists. Instead, the consensus has been to apply the understanding of whiskers that occur on tin plated surfaces (gained through substantial research) to aluminium coated products. In the data centre environment, the first question is where do these tiny predators come from and, secondly, are they really as much of a risk as the online chat would have us believe?
An unpredictable villain
Part of the confusion and the fear factor behind zinc whiskers is the fact that their growth is varied and unpredictable. There is an incubation period of months, or perhaps even years, followed by a period of growth at rates that can
be as fast as 1mm per year, though typically it is less than this. No-one is really sure why they occur, however, the most common theory is that molecular stresses in the electroplated metallic material cause the zinc to attempt to separate from the steel, producing crystals that grow into zinc whiskers. The usual suspects for harbouring
these villains are the zinc plated undersides of raised access floor tiles and the zinc-plated supports on which they sit. However, these are not the only zinc-plated components that go in to making a data centre: other galvanised metal surfaces can be found in air handling grilles, the cable management system and all kinds of fixings throughout the data hall. Indeed, many electronic equipment suppliers use a zinc-plated chassis within their hardware, mounting slides and other components directly inside and outside of the very electronic items that data centre operators are so anxious to protect. What’s more, these leading suppliers are happy to fully warranty the installation. This, surely, should
The internet is awash with discussions about the threat of zinc whiskers and concerns are growing about the risks within the data centre sector. However, very little actual research and testing has been done to ascertain what, if any, actual risk exists.
Image: Cablofil 30 NETCOMMS europe Volume I, Issue 6 2011
www.netcommseurope.com
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