Electronics > Beginners

Truly antistatic bag?

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Mr. Scram:
The problem is that there could be a significant charge without much visibly happening. The answer is using a meter like Dave has used in a number of his videos on ESD. They're fairly expensive meters but can occasionally be snagged on Ebay for a fraction of their original cost. They're comparatively rare though.

Mr. Scram:

--- Quote from: KL27x on May 29, 2019, 07:53:42 pm ---The pink ones are anti-static, too. They protect from outside ESD just as much as the silver ones. The foil bags have a coating of plastic that makes them not much different than the pink ones at ESD protection. The internal conductive foil protects the contents of a silver bag from induced currents, not ESD. It's "EMP protection."

--- End quote ---
That's not what Dave explained in his video. The pink ones are treated not to generate ESD, but won't stop parts inside from being zapped through the bag by an external charge.

KL27x:
Yeah, ok. The pink ones can't stop ESD discharge through the bag, but they dissipate surface charge. Which makes them antistatic bags, but not ESD shielded/proof bags? 

Not being completely ESD-proof doesn't mean they aren't giving significant protection from ESD, either. Dave has a pretty hard time to kill the chip through the bag using his piezo sparker right across the chip. I think it provides significant protection. As Dave says, the air gap and insulation is there. And dissipative coating makes the contents less likely to be the recipient of an ESD in the first place. Plus cardboard box. But  :-// 10kV can spark across 1cm of air... ok. The box is several cm of air. If the chips got in there in good shape, they are gonna come out in good shape.

A (maybe bigger?) problem with a regular plastic bag is an unprotected chip like a FET or a laser diode sliding around in there can die from static/triboelectric buildup. 

kcs:
It is not worth for me to buy specialized tools and test if material has antistatic properties or not as it is one time purchase.

I found it extremely hard to purchase small quantity of wide (>1 m) antistatic bubble wrap or shielding film. I thought I was lucky when I found one listed on eBay.

So, watch out for "antistatic" bags and bubble wraps sold on eBay. Just because it is pink, it does not make it antistatic.

ejeffrey:

--- Quote from: KL27x on May 29, 2019, 08:33:10 pm ---Yeah, ok. The pink ones can't stop ESD discharge through the bag, but they dissipate surface charge. Which makes them antistatic bags, but not ESD shielded/proof bags? 

--- End quote ---

Yes.  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.  That is why everything that goes inside the silver bag needs to be static dissapative (or anti-static).  Hence the pink bags, bubble wrap, foam, etc.  They are safe to use as packaging inside the protected area.

It is the same thing with an ESD workstation.  You don't want to bring materials into the work area that can hold a static charge into the ESD safe area.  So when you receive your box from digikey, you are supposed to unpack it *outside* the ESD work area, then bring the silver bags (and only the silver bags) to your workstation, then open and unpack them there.    Likewise, non-ESD sensitive parts like resistors and capacitors should still be packed in static dissapative bags so that you can safely bring them into your ESD workspace without damaging other components.

Of course this is all the ideal practice.  It is important for production areas, or when working with high sensitivity devices like laser diodes and GHz amplifiers.  What you do in your home workshop is up to you. 

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