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Level 03c, May 2011
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Conductive contamination
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Attention:
Semiconductors and sensitive electronics used in current Information Technology
equipment have allowed for the manufacture of very high density electronic circuitry.
While new technology allows for significant increases or capacity in a smaller
physical space, it is susceptible to contamination, especially contamination particles
that will conduct electricity. Since the early 1990s, it has been determined that data
center environments may 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 very small, and at times not easily seen without the visual aide of
magnifying lenses, this type of contamination can have disastrous impact on
equipment availability and reliability. Errors, component damage and equipment
outages caused by conductive contamination can be difficult to diagnose. Failures
may be at first attributed to other more common factors such as lightning events or
electrical power quality or even just presumed to be defective parts.
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 may be coated with zinc either by a hot
dip galvanize process or by zinc electroplate. The zinc electroplate steel exhibits a
phenomena which appears as whisker-like growths on the surface. These small
particles of approximately 1-2 mm (.04-.08 in.) in length, can break away from the
surface and get pulled into the cooling air stream. Eventually they my be ingested
by the equipment air, settle on a circuit board and create a problem. If you suspect
that you may have this type of problem, contact your IBM Service representative.
Airborne particulates (including metal flakes or particles) and reactive gases acting
alone or in combination with other environmental factors such as humidity or
temperature might pose a risk to the z10 that is described in this document. Risks
that are posed by the presence of excessive particulate levels or concentrations of
harmful gases include damage that might cause the z10 to malfunction or cease
functioning altogether. This specification sets forth limits for particulates and gases
that are intended to avoid such damage. The limits must not be viewed or used as
definitive limits because numerous other factors, such as temperature or moisture
content of the air, can influence the impact of particulates or environmental
corrosives and gaseous contaminant transfer. In the absence of specific limits that
are set forth in this document, you must implement practices that maintain
particulate or gas levels that are consistent with the protection of human health and
safety. If IBM determines that the levels of particulates or gases in your
environment have caused damage to the z10 IBM may condition provision of repair
or replacement of z10 or parts on implementation of appropriate remedial measures
to mitigate such environmental contamination. Implementation of such remedial
measures is a customer responsibility.
Chapter 2. Environmental specifications
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