Talk:Antistatic bag
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How badly can a board be damaged by a static discharge? Is it at all safe to keep them not in anti static bags? —The preceding unsigned comment was added by 198.22.121.110 (talk • contribs).
- Ordinary (non anti-static plastic bags) are very potent static discharge generators. I'd much sooner leave my board unbagged than slip it into a normal polyethylene bag. And even a tiny static discharge can render your board dead; it only takes one critical circuit getting zapped to death.
- Atlant 00:57, 26 May 2007 (UTC)
[edit] Inacuracy re faraday cages
The Pink (and sometimes green) bags are strictly speaking known as low-charging bags. That is, they do not generate any static themselves, however they do not incorperate a faraday cage and so do not protect a PCB from electric fields which can induce a potential difference and therefore current flow. As such they should not be used for PCBs, only for cable assemblies etc. I will try and find some sources to back me up before adding this information to the article.192.93.164.23 15:30, 26 September 2007 (UTC)
[edit] Open bag
I'd say an opened bag provides protection similar to that of a closed bag, for the same reason that a metal cylinder gives protection similar to a closed cage. Provided that the discharge is at the bag/cylinder/cage, not at the object inside. In all these cases, what happens is that the charges of the metal tend to redistribute until they succeed to cancel out any externally applied field. This should mean for the example of discharge on a metal cylinder, there will (a) be charges moving through the system (the discharge current) and (b) a redistribution of the "static charges" (electrons of the metal) in a way that causes electric field strength to be zero inside the tube. Correct me if I'm wrong, but this should mean an open ESD bag gives very good protection for any discharge at the bag (not if it's at the object inside).
Also, I'd think the fact that the shileding has a low resistance in itself should give protection, for example if the ESD source can be modeled as 1kV + 1kohms and an object is protected by a semi-open metal object with 1ohm resistance, then the voltage division by itself should bring the E field down by a fcator 1000.
Some discussion is welcome --88.131.22.138 (talk) 10:34, 8 January 2008 (UTC)
-You may be correct that an open bag can still protect from static discharges, however it will not protect a board from electric fields, which can induce a p.d. on the board and hence cause damage with no physical contact from any source. My knowledge of this is only based on a recent training course however, so an authoritative reference source would be useful (192.93.164.23 (talk) 07:36, 26 February 2008 (UTC))
Reply to comment: According to the well-known book on ESD by Dangelmayer (isbn 0-412-13671-6, page 369), electric fields are in reality never a problem. And I also think an open bag does protect against fields depending on the direction of the field vs the place of the bag hole. For example if the bag is like a cylinder and the field is perpendicular to the cylinder. Or a more useful example: any open bag, as long as the object inside it is well hidden, i e not close to the opening (the "lightning conductor" effect will also make sure any discharge in such a case finds it way through the bag, not the object to be protected) --88.131.22.138 (talk) 10:31, 11 March 2008 (UTC)
