ESD Systems - Questions And Answers

Is it critical for a static shielding bag to be sealed shut? What if a "used" one (already opened) is just folded over and under? - Anonymous

For used bags, it is highly recommended that the user perform some type of bag integrity testing on an ongoing basis. For brand new bags from reputable vendors, the integrity of the bag should be in tact and not needing testing. Either way, if a high quality film was used to manufacture the bag then it should perform as specified by the manufacture and any specifying standards.
Bags can be rendered useless by leaking side seals or holes in the bag.
As long as ESDS device is maintained in a “continuous conductive enclosure” the bag will provide the electrostatic shielding protection that the device needs.

If the product is totally surrounded by the package which I believe means either heat sealed or folded and closed then the contents should be adequately protected from ESD. If the contents are going to be stored for any period of time and or are sensitive to corrosion, the bag should be heat sealed. This is the ultimate protection for the device inside. Folding the opening over onto the bag and securing it with either an ESD label or our ESD protective Yellow opaque tape with symbols will ensure the contents are protected (sealed against ESD but not moisture).

NOTES: The EAI 541 is the most common static shielding specification the spec attempts to determine the shielding ability of bags. They do not heat seal or fold over the bags opening.

ESDA S11.31-1994 STANDARD also does not mention that the bag is heat sealed or folded over.

ESD 541 Standard (soon to be published) does not mention anything about folding or heat sealing either.

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