Packaging for Electrostatic Discharge Protection

As mentioned above, sensitive electronic products require protection from electrostatic discharge (ESD). In unmodified plastics, ESD is a significant problem, since the nonconductive nature of plastics causes them to easily accumulate static charges. Consequently, when plastic packaging is used for sensitive devices, it must be modified to make it less susceptible to charge buildup, and to provide for dissipation of any charges that are created. Both of these are accomplished by providing a conductive path for electrons. 

The most common way to alter the susceptibility of the plastic to static charge accumulation is to add to it some component that attracts and retains a thin layer of surface moisture, and at the same time weakly ionizes it. The ionized water provides the needed conductive path so that static charges will dissipate. The additive can be applied to a surface layer in the material, can be distributed through the bulk of the material, or can even be conhned in an inner layer of a coextruded material. Antistatic additives that are commonly used include ethoxylated amines, quaternary amines, and ethoxylated amides. 

Antistatic packaging materials come in a variety of forms, including Him, foam, bubble wrap, and containers. ESD films in heat-shrinkable form are designed to minimize static generation by friction within the bag, as well as transmission of static charges from outside the bag. These materials are often tinted pink as a visible signal of their antistatic properties. 

An alternative to the use of additives is selection of plastics that are inherently static-dissipative. While such materials are still largely experimental, one promising alternative is polyamide ethylene oxide block copolymers. 

Think of examples of the use of (a) loosefill, (b) molded foam cushions, and (c) foam-in-place cushioning systems. 

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