What Not to Do with an ESD Shielding Bag
Replacement circuit boards or other ESD sensitive items should be handled by the grounded operator or be on a grounded mat. Since the ESD sensitive item comes packaged in an ESD (metal-in or metal-out) shielding bags, many people believe they should continue to use the bag. Some place the shielding bag on the grounded mat and then place the ESD sensitive item on the shielding bag.
Others use the shielding bag in the style of a pot holder when handling the ESD sensitive item. Both of these practices are wrong. The ESD worksurface mat ideally should be 1 x 10^6 ohms and less than 1 x 10^9 ohms, the later being the required limit for worksurfaces per ANSI/ESD S20.20. This is at least 1,000,000 ohms, but less than 1,000,000,000 ohms. The required limit for a Wrist Strap System, that is while being worn, per ANSI/ESD S20.20 is less than 3.5 x 10^7 ohms (or less than 3,500,000 ohms or 35 megohms). The shielding bag likely has a higher resistance, typically 10^10 ohms for metal-in shielding bags) so the path to ground would be higher (since it is resistance in series).