QUESTION - Anti-static bags

[pcm81]

This may be a stupid question,  but are mylar bags considered to also be anti-static? Seems like anti-static bags just have some conductive material added to them, while mylar has a full layer of aluminum as a shield.

[jpanhalt]

Are you concerned specifically about Mylar or just any plastic?

Digikey uses these: http://documents.staticcontrol.com/pdf/Dri-Shield-3400-Moisture-Barrier-Bag.pdf
Note that the plastics (both Polyester/Mylar and polyethylene) are designed to dissipate static.

[m k]

Depends how you treat the word.
If goal is no statics and it's achieved then it doesn't really matter.

But some stuff may also need other covers.
Like a non-conductive Faraday's cage or UV shield.

[pcm81]

We use anti-static bags at work for storing sensitive equipment. I have mylar vacuum bags at home on a roll that i can make any length bag from. Just dawned on me that mylar may be equivalent to esd bag in a pinch when correct size esd bag is not available. Hence the question.

[pcm81]

Are you concerned specifically about Mylar or just any plastic?

Digikey uses these: http://documents.staticcontrol.com/pdf/Dri-Shield-3400-Moisture-Barrier-Bag.pdf
Note that the plastics (both Polyester/Mylar and polyethylene) are designed to dissipate static.

So, as i recall from my ESD training, the esd bag is meant to be a Faraday cage, while the materials inside, pink bubble wrap, are designed not to build up static from motion (dissipative). Mylar seems to be a faraday cage as well...

[m k]

Back in the day components were in pink and greasy plastic bags and Mylar was used for bigger modules.
Nowadays I've got little things in Mylar also, price is down I guess.

I would treat them equal if ESD is the issue.

[m k]

Dang, I've thought it's Mylar if there is aluminum.

[TimFox]

"Mylar" is a registered trademark of DuPont for polyethylene terephthalate (PET polyester) plastic, and other manufacturers have similar trademarks for their product. 
Polyester plastics are available in a wide range of construction, including plain, metalized, etc., some of which (but not most) have anti-static properties.
Anti-static bags are available in several plastics, including the familiar pink polyethylene bags.

[Siwastaja]

Mylar is trade name for a type of PET (polyethylene terephthalate), which is a type of polyester. Such plastics "as is" are highly static generating.

ESD safe products are ESD safe. Look up for the difference between static dissipative and static shielding materials.

They can use any plastic, including Mylar. The key is in the added conductive ingredients.

Color is just color. Its a poor indicator. A real static dissipative bag has words "static dissipative" or similar printed to it.

[jpanhalt]

In post #4, the TS mentions making individual bags from a roll.  I came across a large roll of static dissipative PE very cheaply.  It's about 2" flat.  That is how I store most of my SMD parts that are sensitive (attached).  I single staple holds the top folded over but allow access with tweezers when needed. 

[pcm81]

In post #4, the TS mentions making individual bags from a roll.  I came across a large roll of static dissipative PE very cheaply.  It's about 2" flat.  That is how I store most of my SMD parts that are sensitive (attached).  I single staple holds the top folded over but allow access with tweezers when needed.

According to ESD training my company provides, the bags you are showing will not protect the components inside. The pink bags have no EM shielding properties. Per our rules, we would use pink bags to store sets of components and then have many sets in a larger ESD (metallic color) bag.

[jpanhalt]

No disagreement.  That's why I called them static dissipative.  They are not static shielding.

[Shock]

[m k]

In post #4, the TS mentions making individual bags from a roll.  I came across a large roll of static dissipative PE very cheaply.  It's about 2" flat.  That is how I store most of my SMD parts that are sensitive (attached).  I single staple holds the top folded over but allow access with tweezers when needed.

According to ESD training my company provides, the bags you are showing will not protect the components inside. The pink bags have no EM shielding properties. Per our rules, we would use pink bags to store sets of components and then have many sets in a larger ESD (metallic color) bag.

How they can be used if double bag is a must?

Last time I got a full tube of chips the tube was in metal coated bag.
Clearly a standard procedure.

Back in the day our on-hand component storage had grounded frame with a banana jack and user had a wrist wrap.
The room had also a conductive anti-static floor and users had conductive anti-static shoes and so on.

[Siwastaja]

Static shielding pack alone is always good. Static dissipative pack alone is not. A particularly nasty ESD event from an external source can go through the dissipative pack, it's just that if these dissipative packs rub against each other, they won't cause ESD events by themselves so are safe inside shielding packs.

[jpanhalt]

RE: EEVblog #247 Anti-Static Bag Myth Revisted[sic]
I watched twice and am not sure what the conclusion was.  It seems to me that Dave showed static-dissipative bags (PE) do protect a CMOS device from static under pretty strenuous test conditions.  The momentary failed function of the chip could have been due to charge build up on the CMOS gates or slow start of the signal source.  After a short time, though it worked.

Then in the final experiment after fiddling with the chip in the bag, he was able to produce a permanent failure when arcing directly across the pins.  At the end he said a similar experiment with the static-protective Mylar bag gave protection.
1) That experiment wasn't shown, but I do trust Dave did it.
2) Did Dave test whether the PE bag was punctured by the pins during all of the manipulations?  Similarly, was the Mylar bag tested for punctures?  Was it subjected to the test as many times as the PE bag was?
3) The piezo spark unit was not very reproducible.  What about a using a handheld Tesla coil as is used for leak detection? (My least concern.)

I would draw an analogy to Kevlar vests worn by many law enforcement officers.  They are not "bullet proof," but they certainly are worth the protection they do offer.

[Shock]

The conclusion was you need both dissipative and shielded protection against ESD. The bags are only as good as the manufacturers specifications, as in your analogy you can get fake bags and vests.

Those other questions are pointless. Dave also didn't drive a truck over the bag, but what about a truck? This is why you contact suppliers and manufactures and request the specifications.

You will find in ANSI ESD specs the testing procedure is clearly defined, Daves test was to show what doesn't work and misconceptions, and not testing to a standard or rating.

[jpanhalt]

The conclusion was you need both dissipative and shielded protection against ESD. The bags are only as good as the manufactures specifications, as in your analogy you can get fake bags and vests.

If that is what Dave intended to show, it was not shown.

[Shock]

Noone cares what you think.

[wraper]

I see al lot of smart talk about what is a proper ESD bag and that mylar bag can be anything. Did anyone actually google a "mylar bag"? Normally it's a bag with aluminium layer in it.
EDIT: Basically it's the same thing as ESD moisture barrier bag but marketed for storing food.

[wraper]

The conclusion was you need both dissipative and shielded protection against ESD. The bags are only as good as the manufacturers specifications, as in your analogy you can get fake bags and vests.

Those other questions are pointless. Dave also didn't drive a truck over the bag, but what about a truck? This is why you contact suppliers and manufactures and request the specifications.

You will find in ANSI ESD specs the testing procedure is clearly defined, Daves test was to show what doesn't work and misconceptions, and not testing to a standard or rating.

I don't need specifications to know that a steel jar is electrically conductive and protects internals against ESD, even though it has no such specifications.

[TimFox]

I do need specifications (or a visual inspection) to see if a given Mylar product includes a metal layer.
My Mylar envelopes for photographic materials do not.

[m k]

Outside is then covered but how is the inside?
What if it's a used bag and last time there were Scotch tape wrapped in Scotch tape.

[Cerebus]

This video will tell you everything you need to know about anti-static bags. It's a talk by Dan Anderson the original designer of the pink poly anti-static bag. It's well presented and Dan is entertaining.

Don't watch if you're the type to be triggered by the attitudes of a bald middle-aged 1970's medallion man; but if you are, you probably have a sociology lecture to get to anyway* so you won't have the time.



*Yes, yes you do. University is not all about smoking weed in the halls of residence, you really do need to go to those lectures, although if all you're going get at the end is a sociology degree you could save yourself a lot of time by just buying a packet of Andrex or Izal ("The Calvinist's Choice"). 

[Siwastaja]

Did anyone actually google a "mylar bag"? Normally it's a bag with aluminium layer in it.

You demonstrate the danger of using inexact language - it's highly domain specific. Some electronic designers could use "mylar" for shortcut name for the ESD shielding bags, but others won't, I have actually never heard anyone saying that! The point is, it's just ... wrong. Mylar is well defined term, look it up. It's a brand name, yes, and I could accept calling other similar PET films "mylar" as well, but adding aluminium to belong as a part of the name is a stretch!

For me, "Mylar" defaults to the polyester material itself, definitely with no aluminium layers in it; the opposite to you. I.e., the correct meaning. This is because I have bought products branded as Mylar, like Mylar film as a roll-ware, and some photography things. In electronic packaging, I just have never heard it at all.