Electronics > Beginners
Truly antistatic bag?
KL27x:
^Agreed.
But I am gonna challenge this one sentence.
--- Quote ---The silver bags provide a barrier that protects the things inside the bag from static discharge outside the bag. The bag doesn't protect its contents against static buildup inside the bag.
--- End quote ---
I would think the silver ones have more or less the exact same antistatic dissipative surface treatment as the pink ones. If I have a handful of IC and no proper tube, I put them naked in the silver bags.
Wikipedia
--- Quote ---Conductive antistatic bags are manufactured with a layer of conductive metal, often aluminum,[3] and a dielectric layer of plastic[2] covered in a static dissipative coating.[6] This forms both a shield and a non-conductive barrier, shielding the contents from static charge via the Faraday cage effect.
--- End quote ---
I don't like the last sentence.
... shielding the contents from static charge electrostatic discharge via a Faraday cage. Protection from low voltage/curent by dielectric properties of PET. And protection from surface charge buildup by virtue of dissipative coating.
Interesting:
--- Quote ---In addition, they have a limited shelf life, as the metal substrate can deteriorate over time.
--- End quote ---
I would have thought the antistatic coating would be what wore off/out.
Illusionist:
I always thought the metalised, silver bags (which are usually metalised Mylar® (a polyester from Dupont)) are mostly intended to be vacuum and heat sealed to protect the contents from moisture.
I've received a lot of component samples packed that way, with instructions to bake before soldering if opened for too long beforehand or if the packet was compromised.
The aluminium layer between the polyester sheets is a moisture and air barrier. The polyester itself is surprisingly bad at that. The be static dissipative, the bags still need a surface coating.
It's also used to seal food for long term storage for the same reasons. Off topic, but yesterday I opened a 5kg bag of barley that I sealed that way myself seven years ago. It's still perfect.
ejeffrey:
--- Quote from: KL27x on May 29, 2019, 09:38:55 pm ---^Agreed.
But I am gonna challenge this one sentence.
--- Quote ---The silver bags provide a barrier that protects the things inside the bag from static discharge outside the bag. The bag doesn't protect its contents against static buildup inside the bag.
--- End quote ---
I would think the silver ones have more or less the exact same antistatic dissipative surface treatment as the pink ones. If I have a handful of IC and no proper tube, I put them naked in the silver bags.
--- End quote ---
Yes, my point was that _if_ you need to put other packaging materials (bags, foam, bubble wrap) inside the shielding bag, you want that to be static dissipative, otherwise it could damage your components and the outer bag can't effectively protect against that.
Monkeh:
--- Quote from: Illusionist on May 30, 2019, 08:57:51 pm ---I always thought the metalised, silver bags (which are usually metalised Mylar® (a polyester from Dupont)) are mostly intended to be vacuum and heat sealed to protect the contents from moisture.
I've received a lot of component samples packed that way, with instructions to bake before soldering if opened for too long beforehand or if the packet was compromised.
The aluminium layer between the polyester sheets is a moisture and air barrier. The polyester itself is surprisingly bad at that. The be static dissipative, the bags still need a surface coating.
It's also used to seal food for long term storage for the same reasons. Off topic, but yesterday I opened a 5kg bag of barley that I sealed that way myself seven years ago. It's still perfect.
--- End quote ---
The moisture barrier bags are another type again. Standard shielding bags are transparent but silvery or grey - it's a sputtered metal layer, not a full one. It's basically a thin film resistor in bag form. The fully metallised ones are, as you say, moisture barriers.
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