Conductive contamination

Contaminants that conduct electricity need to be reduced in data center environments.

Semiconductors and sensitive electronics that are used in current information technology equipment allow for the manufacture of high-density electronic circuitry. Although new technology allows for significant increases or capacity in a smaller physical space, it is susceptible to contamination, especially contamination particles that conduct electricity. Since the early 1990s, it was determined that data center environments might contain sources of conductive contamination. Contaminants include carbon fibers, metallic debris such as aluminum, copper and steel filings from construction, and zinc whiskers from zinc-electroplated materials used in raised floor structures.

Although small, and at times that are not easily seen without the visual aid of magnifying lenses, this type of contamination can have disastrous impact on equipment availability and reliability. Errors, component damage, and equipment outages that are caused by conductive contamination can be difficult to diagnose. Failures might be at first attributed to other more common factors such as lightning events or electrical power quality or even presumed to be defective parts.

Zinc whiskers

The most common conductive contamination in raised-floor data centers is what is known as zinc whiskers. It is the most common because it is frequently found on the underside of certain types of access floor tiles. Typically, the wood core style floor tile has a flat steel bottom. The steel might be coated with zinc either by a hot-dip-galvanize process or by zinc electroplate. The zinc electroplate steel exhibits a phenomena that appear as whisker-like growths on the surface. These small particles of approximately 1 - 2 mm (0.04 - 0.08 in.) in length can break away from the surface and get pulled into the cooling air stream. Eventually they might be ingested by the equipment air, settle on a circuit board, and create a problem. If you suspect that you might have this type of problem, contact your IBM® Service representative.

The following figure shows light reflection from zinc whiskers.