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Teledyne API – Model T700 Dynamic Dilution Calibrator A Primer on Electro-Static Discharge
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Use metallic anti-ESD bags for storing and shipping ESD sensitive
components and assemblies rather than pink-poly bags. The famous, pink-poly
bags are made of a plastic that is impregnated with a liquid (similar to liquid laundry
detergent) which very slowly sweats onto the surface of the plastic creating a
slightly conductive layer over the surface of the bag.
While this layer may equalizes any charges that occur across the whole bag, it does not
prevent the build up of static charges. If laying on a conductive, grounded surface, these
bags will allow charges to bleed away but the very charges that build up on the surface
of the bag itself can be transferred through the bag by induction onto the circuits of your
ESD sensitive device. Also, the liquid impregnating the plastic is eventually used up
after which the bag is as useless for preventing damage from ESD as any ordinary
plastic bag.
Anti-Static bags made of plastic impregnated with metal (usually silvery in color)
provide all of the charge equalizing abilities of the pink-poly bags but also, when
properly sealed, create a Faraday cage that completely isolates the contents from
discharges and the inductive transfer of static charges.
Storage bins made of plastic impregnated with carbon (usually black in color) are also
excellent at dissipating static charges and isolating their contents from field effects and
discharges.
Never use ordinary plastic adhesive tape near an ESD sensitive device or to
close an anti-ESD bag. The act of pulling a piece of standard plastic adhesive
tape, such as Scotch
®
tape, from its roll will generate a static charge of several
thousand or even tens of thousands of volts on the tape itself and an associated
field effect that can discharge through or be induced upon items up to a foot away.
06873B DCN6388