EEVblog #247 - Anti Static Bag Myth Revisted

hi why am I wearing the lab coat well it's myth-busting time kind of revisit an old myth I did back right in episode number three it's the pink anti-static bag myth now as the myth goes I'm these pink anti-static bags and also these anti-static tubes anti-static okay in quote marks they're supposed to protect your OCS and well that it really is a myth and I said that back in episode 3 these do not protect your devices at all I can desert my chips straight through this bag and straight through that anaesthetic tube what you need is one of these metal shielding bags now I did in episode three is I just talked about it I didn't actually demonstrate it so I thought I'd do just that for this episode it's really interesting and what prompted me to do this is element 14 slash funnels if you've been following my tweets actually this is how they sent me my chips no proper static shielding bag at all they just sent it in the anti-static tube and the anti-static pink ESD bag not good enough not by a long shot somebody wasn't thinking didn't have their head screwed on but if that happened to the company and you ordered them they were you would find out element 40 would fail an ESD orden their company would be blacklisted and oh all hell would break loose so you've got to take ESD seriously if you're a component distributor and not only just shipping the stuff because that's important but handling in your factory as well now granted they did actually call me up and admitted that yes they're aware of it they screwed up it came from their Singapore factory or something and they're investigating whatever so anyway I thought it would be a real interesting thing to actually do a real test can we see the difference between a proper static shielding bag while these ESD bags let's go the only good thing that this act that this anti-static tube is going to do is that when you handle and move it around the surface itself the plastic surface is not going to build up a static charge because it is actually are treated with an anesthetic and an estate material that actually stops the charge building up on the surface of the plastic and this pink anti-static bag that the element14 parts actually came in is no different to this plastic it's just like a in this case it's probably just like a polyester type bag and it is coated with an anti-static material art hence giving it that pink sort of effect but they don't necessarily always have to be pink white that they can actually be clear like these are tubes now these anti-static bags are also known as static dissipative so if you see it's the same thing static dissipative is effectively the same thing as anti-static so what you need to protect your devices is one of these static shielding bags typically are they'll have like a metal film inside of them and they're they're kind of not quite as see-through as the other bags but once you put your chips inside one of these static shielding bags or a conductive bag you can also get a black bag which is actually conductive that will do exactly the same thing and once your devices are in there they'll throw them around do whatever you want that joins up and you won't be able to actually kill the devices inside but these bags and these chews do absolutely nothing I can walk up to this if I'm charged I can go zap and kill that device right through that bag and that tube so why bother having these bags and these tubes at all if they're no good for protection well the idea is that they do not build up a charge so when you're using them on your SD mat like this or you're in what's called your ESD safe area where everything's grounded you've got your wrist strap on and everything everything on these benches on it in an anti-static area should be our static disappear but it should be anti-static so I can shuttle this around the surface like this and it's not going to build up a charge I can get to bags like this and I actually rub them together like this two bags and they will not actually build up a charge because that's how you build up a charge using the triboelectric effect you get two different materials and you rub them like that you're familiar with that you know walking across the carpet or rubbing your jumper with something with it you know comb things like that you can generate static charge between two surfaces so how are we going to test this well what I've got here is a surface DC voltmeter and this will actually give me a direct readout in thousands of volts ie kilovolts at on any surface that is behind this metal sensor plate on the back so we can actually measure the charge on a surface and also see if any charge gets through these pink ESD bags or the study shielding bag and to generate a spark I've what I've done is I've got one of these little piezoelectric spark generators there it goes like that and we can generate ouch got myself there we can generate a spark and I actually got this out of one of these our butane BBQ light is one of the trigger-based things you pull the trigger and the flame comes out because the spark at the end of this piezoelectric igniter generates the butane come in from here and you can get them out of cigarette lighters and all sorts of things so it's not exactly the best I'd rather use a proper are ESD gun you can actually buy proper guns which actually generate what's called a human body model charge like it's a known designated charge into your device but we don't have that I think this will be a decent substitute let's try it out you need about 10 kilovolts or so rough rule of thumb per centimeter per 10 millimeters to jump across there like that but it depends on the atmospheric conditions and all sorts of stuff okay so let's do some practical demonstrations if we can I've got my surface DC voltmeter here and as I said it measures directly in kilovolt so what you're reading is one point zero zero at kilovolt so that is eight faults at the moment that is displaying and that's relative to one inch below the surface of that plate there so if I reset it as you can see I've got it grounded to my anti-static mat underneath so I'll zoom out here and we can put various things under here and we can actually see the effect of the charge on those surfaces now I'm just standing here I've got my lab coat on not that that matters but I'm not haven't got my wrist strap on at all and there you go 30 30-yard volts that's what might that's what my body's actually at you know your regular bubble wrap that you're no doubt familiar with let's put it under here and see what is just generating many hundreds our five hundred odd volts in this case our negative 500 volts now let's take some mylar wrapping which is from my MakerBot and let's put that under there and have a look at that well look at that two thousand volts three thousand volts huge at generate generating massive voltages on the surface four thousand volts generating massive voltages as I peel that off and the triboelectric effect is that working on that mylar wrapping this is horrible stuff let's take our pink final bag and put that under there look it's generating nothing and that's exactly what you'd expect that's what these anti-static bags are designed to do they're not designed to build up a charge at all no matter how you handle them here's another pink one I'm rubbing them together like this and we can't generate anything at all these what these are doing exactly what they're supposed to do they're anti-static how about a drawer of resistors one of these non anti-static our drawers in non anti-static bags and of course they're not really going to kill the resistors in there but if you put that under there it generates there's hundreds of volts so probably the last thing you want to do is throw your chips directly in one of these non static dissipative non anti-static drawers in fact the good quality component drawers they will be made of a conductive plastic what happens when we get our little spark generator here and we do some stuff under it there we go 11 kilovolts 14 kill volts and that's actually charge building up on the surface of the plate in there so that will actually stay there now and build up and this one only goes to twenty kilovolts maximum there you go it's overloaded so what happens when we stick our static generator inside one of these pink then the funnel pink ESD Bank well let's give it a go bang overloaded there you go we just zapped straight through this pink ESD bag not a problem at all not surprising so let's now try one of these static shielding bags let's put it inside here and see if we can generate the same charge now got to be careful not to touch the bottom plate here because I can actually if I do that with the bag just the bag on its own can actually induce voltage you're not actually supposed to touch that plate so we'll reset that okay I'll try and it's inside the bag I'll try and get it as close as possible to the sensor and there you go it's not generating that's only a couple of millimeters away from the sensor plate and it's generating no charge at all because nothing is escaping that bag and it doesn't matter whether it's from inside out or from outside in you put your devices in here if fully protected and if you're wondering about that anti-static tube well it's not going to do anything either let's it's going to work exactly what the pink is deeb a bang there we go for an hour five thousand volts not a problem now here's an interesting one I've got the digi lint chip kit max 32 poured in here and let's take a look at it what does it come with in the packaging there's this foam on the bottom of it doesn't look like ESD fine to me it's not the pink stuff it's not conductive looks like regular foam let's try it out shall we remove this look at that couple hundred volts right there look that's nasty I can generate in the order of look kilovolts it was going up the kilovolts there that's rather nasty stuff when you don't use proper ESD material now i'm granted a fully populated board like this is pretty robust so the odds of killing it are very small but still that is not proper ESD protection at all crazy look at that for kilovolts and let's try that same thing if you got proper conductive five another problem whatsoever generates nothing and there you go yes it is actually conductive about five K but again with one of these little imbed platforms it comes on to that pink anti-static foam and let's play around with this to our hearts content rub the pins do whatever play around not a problem whatsoever you get this horrible non anesthetic foam stuff look at that thousands of volts so although these static shielding bags will protect any device you put inside it's only if all of the objects including the tubes all the foam material inside is anti-static as well or static dissipative if you put one of these this horrible looking thing inside that can generate thousands of volts if you stick that inside there with your devices is screwed all right so enough of that how about we actually try and kill a chip well I've got a 4000 series up CMOS device here and an MC 145 69 and I've got it just flash in an LED to show that it actually works so what we'll do is we'll start a baseline I switch it off we've got a working chip let's take it out I'll just get rid of that for a second and let's try and kill it shall we this is pretty nasty stuff for a 4000 series CMOS device so this is a real baseline test this is directly on the chip itself and let's put it back just as a reference to see if we can actually kill one of these things and yep there you go bingo dead so we were able to kill it so we've got a baseline let's see if we can do that through various anti-static protection devices so let's actually give this a go I'm going to switch off the power there take the chip out and put it in a anti static tube and let's see if we can kill it generate away moods going over the top surface there oh that's interesting check this out woah look on the scope here - higher voltage is being applied to the waveform generator B and C oops anyway let's take it back down and let's take that out hope I didn't kill my function Jen but it at least knows and what there you go well I don't know we might have killed our function Jen let me night there we go the waveform jens on no we couldn't kill it gonna have to try harder so what we got is our working circuit switch it off take you up chip and i'll put it inside one of these pink ESD bags now because we're dealing with a surface in addition to the air here it's these bays to actually provide a modicum tiny amount of protection just because they're not direct contact and so I'll fold it over like that and that will give us a better path to try and get our spark to jump through the bag which is what we want not over the surface like if I put it like that you'll probably said jump over the surface like that there we go we don't want that we want to go through one day I saw a jump through the bag then didn't jump over it jumped well and truly through that bag which of course is the whole point oh it's supposed to be able to do this but it's going to be harder to destroy this device and it was just when we will do in direct contact or very close to it in free air there we go ha ha we killed it we got it to die through one of these pink ESD bags it was more difficult than it was just in free air that's because it does actually provide some barrier if we had a proper ESD gun we would find it to probably go straight through this really easily but it took a little bit of work there to actually get it to finally kill the device but we did so there you go I'm going to call that myth busted these pink ESD bags and the one the funnier one came in they do not provide protection for your devices they provide a little tiny amount just for the fact that they're actually you know an extra distance away and they're not an air gap but that's that's all they're not designed for ESD protection at all they just won't build up a charge on the surface and I hope we've proven that today would have been better if we had an ESD gun we couldn't kill one within a tube because the distances in there a greater and the wall is thicker if we had a proper ESD gun I have little doubt that we would have eventually been able to kill a device directly through one of these ESD tubes as well and I won't bore you with the details but no I could not kill anything inside one of these static shielding bags and no surprise that's what they're designed to handle they're been tested to do that so once you put your devices in there they're fully protected mythbusted catch you next time you

Channel: EEVblog

Views: 271,303

Keywords: anti-static, static, esd, myth, busting, bag, tube, packaging, wrist, strap, grounding, dc, surface, voltage, meter, measurement, piezo-electric, generator, lighter, Static Electricity, Antistatic Agent

Id: imdtXcnywb8

Length: 18min 10sec (1090 seconds)

Published: Thu Feb 23 2012

Reddit Comments

[u/MrSparkle666]

This seems to be a lot of complaining over nothing. The main issue with transporting MOS devices in plastic bags is the static buildup on the bag itself. Normal plastic containers are notorious for building up static charge, which could easily damage the components when removing them from the bag. The pink bags solve this problem just fine.

This guy seems to be really distressed over the fact that a static discharge can damage a component through the bag, which can happen, but it's just not all that common in a real world situation where safe ESD practices are instituted. The build-up on the bag itself is the more serious problem.

Those metallic bags are fairly expensive and so they are often reserved for more expensive components. Using them for shipping every little 50 cent MOS device would not be practical, since it would greatly increase costs, and static discharge through a plastic bag is probably unlikely if people in the lab are using safe ESD practices in the first place.

It's important to educate people so they know that those pink bags do not protect against ESD, but what this guy is insisting upon is quite frankly a little overboard and just not practical.

[u/20bees]

Whoa. I have this pink filth all over the place!!

[u/quantumripple]

Hmm, if I charge myself up and then grab a MOSFET by its gate, does it actually cause damage if the MOSFET is unconnected? I'm trying to imagine why the damaging charge flows into the device if it doesn't have anywhere to flow out. Is this about, say, the gate-channel capacitance forming a capacitive divider with the self-capacitance of the channel?