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After grounding the ESD mat and wearing the properly grounded anti-static wrist strap, what is the correct process to take the contents out of the static-shielding bag and take it onto the antistatic work surface (ESD mat) and why?

(The content of the bag I have in mind is a pcb, in specific a single-board computer).

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Antistatic precautions mean you should never move a device through a large potential difference.

Once you and the ESD mat are connected to ground, they are at the same 0v potential. Take hold of the bag, this bring it and its contents to 0v. Now you can open the bag and handle the devices with anything that's also at 0v. This includes fingers, or conductive things you are holding. So metal tweezers, 'antistatic' pliers that have special conductive plastic handle covers, cotton gloves (which retain enough moisture to be slightly conductive) but NOT tools with insulating handle covers or plastic gloves.

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  • \$\begingroup\$ Great comment about not using non-conductive tools. \$\endgroup\$ – TimB Apr 5 '18 at 16:32
  • \$\begingroup\$ Why does holding the bag bring me and the content to equal potential "safely" (I mean, what is the brief theory behind this)? \$\endgroup\$ – ForeverNoob Apr 5 '18 at 16:52
  • \$\begingroup\$ Holding the bag brings you and the bag to the same potential because your body is conductive. The human body has a resistance between 100k Ohms for dry skin to as low as 1k Ohms for wet and sweaty skin. The wrist strap and anti-static mat are, for comparison, is typically grounded through a 1M Ohm resistor in order to limit current and prevent electrical shock should high Voltage finds its way on ground. \$\endgroup\$ – TimB Apr 5 '18 at 18:50
  • \$\begingroup\$ Does this mean that the charge travels from the inside of the bag to its outside and onto me (or the other way around, depending on the potential), but it does so in a slower way, so as to avoid an ESD? Because if the bag is closed, the charges inside the bag are not supposed to "get out" of it. Or do I miss something? \$\endgroup\$ – ForeverNoob Apr 5 '18 at 21:51
  • \$\begingroup\$ I see your question now. No, the bags are not conductive between the inside and outside. They only act as a Faraday cage to contain any charge build up on the outside preventing it from conducting into the bag and the contents. This is why you shouldn’t use anti-static bags with holes as it allows for a possible charge flow between from the outside to the inside, if a pin of the board is poking through and making contact with both sides of the bag. The inside of the bag and the contents should have no charge because you took anti-static precautions then putting the contents into the bag. \$\endgroup\$ – TimB Apr 6 '18 at 2:19
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You may lay the bag on the anti-static mat to place the bag at the same potential as the mat (although you will do this by handing the bag with your wrist strap on). Then, open the bag, remove the contents while wearing your wrist strap, and place the contents on the anti-static mat.

Do not take the board out of the bag without a wrist strap on, and walk it over to the anti-static mat. The act of walking with the board out of the bag can build up static charge. This will then cause a discharge when you place it onto the anti-static mat, possibly causing damage. Wear your properly grounded wrist strap every time you handle the board out of the bag, and only place it on a properly grounded anti-static mat grounded to the same potential as your wrist strap.

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