ESD Systems - Questions And Answers

I need to store and protect my circuit boards and am looking at some ESD bags. What type of bag should I choose or need? - Anonymous, Boston, MA

There are three basic ESD control characteristics for Bags:
- Low charging, antistatic - reduces tribocharging generation of charges
- Dissipative or conductive - able to remove charges to ground
- Shielding - creates a Faraday Cage & limits the penetration of an electrostatic field and attenuates an electromagnetic field resulting from an electrostatic discharge.

Pink Poly is topically treated and has only a temporarily low charging, antistatic characteristic.
Statfree® Ultra Clear ESD Barrier Bags are permanent low charging and dissipative, appropriate for packaging ESD susceptible items within an ESD protected area, as well as packaging non-ESDS items to be brought into an ESD protected area.

Statshield® Transparent ESD Shielding Bags have all three ESD control characteristics and are low charging, dissipative, and shielding, appropriate for storing or transporting ESDS outside an ESD protected area.
Statfree® Ultra Clear ESD Barrier Bags provides superior ESD protection and is better value than pink poly bags. Pink poly is often a poor choice as it:

1) will tribocharge generating static charges to greater than 300 volts
2) contains in the film amine compounds that will contaminant sensitive parts attacking and corroding solder joints.
3) is dependent on humidity and will lose its ESD protective properties as the environment becomes dryer
4) has ESD electrical properties that are not permanent; “treatment” migration to surface can be transferred to persons or parts eventually the becomes insulative.

Pink poly bags only limit tribocharging. Not being dissipative, whatever charges are generated will be on the bag as an isolated insulator [even when place on a properly grounded ESD worksurface, charges will not be removed to ground]. Not being shielded, the contents will not be protected from electrostatic fields, external charging or ESD events to the package. In some cases, the protective properties of the pink poly bags are temporary and may bleed out over time, rendering the bag high charging as well as contaminating the contents.

A fundamental ESD control principle of ANSI/ESD S20.20 is “Transportation of ESDS items outside an Electrostatic Protected Area requires enclosure in static protective materials; low charging and static discharge shielding materials are recommended.” Per Paragraph 6.2.4.2. Packaging Guidance, “The objective of ESD protective packaging is to prevent a direct electrostatic discharge to the ESDS item contained within and allow for dissipation of charge from the exterior surface. In addition, the packaging should minimize charging of the ESDS item in response to an external electrostatic field and triboelectrification. Packaging materials may outgas, contaminate or shed particles that may cause production-related problems. It is important that the Organization evaluate ESDS protective packaging materials for process, storage and environmental compatibility.

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