QUESTION - Anti-static bags - Page 1
Forum section: electronics / beginners

author: pcm81
author_rank: Regular Contributor
timestamp: February 08, 2022, 12:25:36 am
content: 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.

author: jpanhalt
author_rank: Super Contributor
timestamp: February 08, 2022, 07:55:36 am
content: Are you concerned specifically about Mylar or just any plastic?Digikey uses these:http://documents.staticcontrol.com/pdf/Dri-Shield-3400-Moisture-Barrier-Bag.pdfNote that the plastics (both Polyester/Mylar and polyethylene) are designed to dissipate static.

author: m k
author_rank: Super Contributor
timestamp: February 08, 2022, 11:45:46 am
content: 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.

author: pcm81
author_rank: Regular Contributor
timestamp: February 08, 2022, 02:42:05 pm
content: 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.

author: pcm81
author_rank: Regular Contributor
timestamp: February 08, 2022, 02:45:54 pm
content: Quote from: jpanhalt on February 08, 2022, 07:55:36 amSo, 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...

author: m k
author_rank: Super Contributor
timestamp: February 08, 2022, 02:53:42 pm
content: 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.

author: m k
author_rank: Super Contributor
timestamp: February 08, 2022, 03:51:30 pm
content: Dang, I've thought it's Mylar if there is aluminum.

author: TimFox
author_rank: Super Contributor
timestamp: February 08, 2022, 04:53:18 pm
content: "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.

author: Siwastaja
author_rank: Super Contributor
timestamp: February 08, 2022, 04:56:05 pm
content: 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.

author: jpanhalt
author_rank: Super Contributor
timestamp: February 08, 2022, 05:12:52 pm
content: 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.

author: pcm81
author_rank: Regular Contributor
timestamp: February 08, 2022, 11:51:36 pm
content: Quote from: jpanhalt on February 08, 2022, 05:12:52 pmAccording 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.

author: jpanhalt
author_rank: Super Contributor
timestamp: February 09, 2022, 12:45:33 am
content: No disagreement. That's why I called them static dissipative. They are not static shielding.

author: m k
author_rank: Super Contributor
timestamp: February 09, 2022, 11:17:01 am
content: Quote from: pcm81 on February 08, 2022, 11:51:36 pmHow 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.

author: Siwastaja
author_rank: Super Contributor
timestamp: February 09, 2022, 12:04:01 pm
content: 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.

author: jpanhalt
author_rank: Super Contributor
timestamp: February 09, 2022, 01:33:33 pm
content: RE: EEVblog #247 Anti-Static Bag Myth RevistedI 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.

author: Shock
author_rank: Super Contributor
timestamp: February 09, 2022, 02:18:42 pm
content: 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.

author: jpanhalt
author_rank: Super Contributor
timestamp: February 09, 2022, 02:22:05 pm
content: Quote from: Shock on February 09, 2022, 02:18:42 pmIf that is what Dave intended to show, it was not shown.

author: Shock
author_rank: Super Contributor
timestamp: February 09, 2022, 02:22:49 pm
content: Noone cares what you think.

author: wraper
author_rank: Unknown
timestamp: February 09, 2022, 02:37:22 pm
content: 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.

author: wraper
author_rank: Unknown
timestamp: February 09, 2022, 02:47:55 pm
content: Quote from: Shock on February 09, 2022, 02:18:42 pmI 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.

author: TimFox
author_rank: Super Contributor
timestamp: February 09, 2022, 02:57:28 pm
content: 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.

author: m k
author_rank: Super Contributor
timestamp: February 09, 2022, 07:18:44 pm
content: 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.

author: Cerebus
author_rank: Super Contributor
timestamp: February 10, 2022, 02:52:00 am
content: 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").

author: Siwastaja
author_rank: Super Contributor
timestamp: February 10, 2022, 08:25:02 am
content: Quote from: wraper on February 09, 2022, 02:37:22 pmYou 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.

author: Siwastaja
author_rank: Super Contributor
timestamp: February 10, 2022, 08:29:35 am
content: Quote from: jpanhalt on February 09, 2022, 01:33:33 pmIt's not surprising.People always make the same mistake; getting confused if a test shows thatfailure rate is not 100%, for a product or procedure which sole purpose is to make the failure rate say below 0.00000001%.You usually can't see "the point" by simple tests, at all.Given some luck, the tested chip might have survived even without any packaging at all.Practically, the dissipative packs are so much better than any random plastic bags. But, if an assembly company handles specifically sensitive parts (like some RF MOSFETs), in thousands, the ESD procedures need to be to the letter. Failure of 1% of the units after 6 months of use would be a disaster.

author: wraper
author_rank: Unknown
timestamp: February 10, 2022, 08:54:39 am
content: Quote from: Siwastaja on February 10, 2022, 08:25:02 amIt's not about what "Mylar bag" can possibly mean in all possible cases but about what OP actually asks.

author: Siwastaja
author_rank: Super Contributor
timestamp: February 10, 2022, 09:01:04 am
content: Oh yes, OP said they happen to have bags with aluminium, so there is no confusion this time. We can assume the OP is talking about ESD shielding bags, thanks to that clarification.But, if we don't correct OP's terminology, the risk of OP continuing to talk about "mylar bags" when theyactuallymean "ESD shielding bags" is high, and this has at least two practical consequences:* Confusion in further communications,* Someone (OP themselves, or someone else) getting the wrong kind of bags.Also, I wouldn't use Mylar food storage bags for storage of ESD sensitive part, even if they have aluminium layer. Proper ESD shielding bags are not expensive, they also have printing which tells you they are static shielding / moisture barrier bags. And you usually accumulate those bags anyway when ordering from component distributors, and they can be reused for many many times.Indeed if you just google "Mylar bag" you mostly get image results of foil bags but that being said, most of the results actually do not contain the string "Mylar bag", Google is just finding products described as "Mylar foil bag", "Foil bag", "Mylar barrier bag" etc. These added words make a big difference!I don't understand your motivation here. I'm sure OP posted the question exactly to gain understanding about the types of bags and the terminology. It's not that we are correcting the wrong assumptions and terminology out of malice, quite the opposite.

author: Cerebus
author_rank: Super Contributor
timestamp: February 10, 2022, 07:07:52 pm
content: Quote from: Siwastaja on February 10, 2022, 08:25:02 am'Mylar' is the DuPont trade name for [Biaxially oriented] PolyEthylene Terephthalate (BoPET) film. Another trade name for it is Melinex. In the UK plastics trade 'Mylar' has tended to be used as a generic for the plain film, and 'Melinex' as a generic for the mirror finish aluminised version of the foil as Melinex had the first commercially available mirror finish aluminised version. The use of 'Melinex' as a generic seems to have fallen out of fashion, at least, I haven't heard it used in years, but it used to be a commonplace.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: February 10, 2022, 09:59:59 pm
content: I want to know what kind of bags they used in "Warehouse 13"They seemed to contain all sorts of bad stuff

author: jpanhalt
author_rank: Super Contributor
timestamp: February 10, 2022, 10:08:19 pm
content: Quote from: Wallace Gasiewicz on February 10, 2022, 09:59:59 pmEEVBlog a reality show. Special effects are very limited.

author: wraper
author_rank: Unknown
timestamp: February 11, 2022, 09:46:54 am
content: Quote from: Siwastaja on February 10, 2022, 09:01:04 amI'm pretty sure op asked:QuoteHence if the "Mylar" bags he has can be used as ESD bags, not about correct terminology.