Motherboard static bags. Outside of them no good for the mobo.

[Ed.Kloonk]

I'm talking about a brand new motherboard. You take it out of the anti static bag, and place it on the bag in readiness to either install it into a case or even plug in power and start it up right on the bag.

I've just read that the anti static bag is not effective in static reduction on the outside and therefore dangerous to the mobo when placing the board on it.

Can anyone here confirm?

http://www.techpowerup.com/forums/showpost.php?p=636310&postcount=12

[Psi]

Do you really want something even mildly conductive in contact with all the throughhole pads when powering the board up?

It wouldn't surprise me if the coating is only one sided, probably saves money to manufacture the bags, but i can't confirm.

[digsys]

There's no one answer, so play it safe and DON'T put it on the bag. You have no idea who makes the bags or even if they are the same each time.
So there's no point. As the link says, use the box it came in.

[Psi]

They're pretty well ESD protected.
As long as you don't go running around rubbing motherboards on the carpet you should be fine

(Unless you live somewhere really really dry and know you have static issue, then some precautions might be in order)

[dexters_lab]

must admit i have never placed a board on the esd bag simply because it will be conductive.

usually just use the box it came in

[mariush]

Why would you put the motherboard on something that has unknown properties on its exterior, when you have perfectly good CARDBOARD available, that you know it's an insulator?

ffs. Even a couple of A4 sheets of paper are better than using an antistatic bag.

[David_AVD]

I seriously doubt that a motherboard would be affected by running it whilst sitting on top of a static dissipative bag.  Even the inside of it poses no risk of shorting something out.

[Chalky]

Why would you put the motherboard on something that has unknown properties on its exterior, when you have perfectly good CARDBOARD available, that you know it's an insulator?

ffs. Even a couple of A4 sheets of paper are better than using an antistatic bag.

I was taught that cardboard & paper were a no-no for ESD-sensitive devices.

[Moshly]

I seriously doubt that a motherboard would be affected by running it whilst sitting on top of a static dissipative bag.  Even the inside of it poses no risk of shorting something out.

I have seen an anti-static bag smoke up & melt (clear plastic type with the black printed grid).
No electrical damage to the board, just a bit of smoke damage.
Also seen that black foam that IC's ship in do the same 

[David_AVD]

I'm very surprised to hear that about static dissipative bags.  I'm sure I've tried to measure the resistance and found they are many meg Ohms.  Metalised bags would be a different story of course.

[TerraHertz]

Anti-static procedure: Step one, understand what static is, and how to avoid discharging it through electronics.

Anti-static conductive bags on the *inside*, are a kind of high-impedance Faraday cage. Charge equalizes across the surface of the bag, thus preventing the mobo from seeing differential charges from point to point on the board. But the bag isn't copper foil, it's a high impedance film. You can still kill a board inside an anti-static bag, with enough of a discharge to the bag to produce a damaging differential spike across the bags resistive surface.

But seen from the outside, the bag is a conductive sheet. You put the bag down on the table and let go, the bag assumes the charge of the table surface. Meanwhile you are holding the mobo, and it has the same charge as your body. You take a few steps across a carpet, or anything really in your thick rubber soled shoes. Congratulations, you and the board are now at several KV. Though only with a few pF of capacitance to free space, so *you* usually won't notice the charge equalization when you touch something else conductive but with a different charge.

Now you put the mobo down on the 'anti-static' bag. And you didn't first touch the bag with your other hand because why should you, it's 'anti-static', right?
Wrong. Your body equalized charge through the mobo to the capacitor built of a conductive plastic film in contact with the table surface. Zap!

Simple (real) rules:
1. Always touch both things/places first and simultaneously with the electronics, when transferring bare electronics from one place to another. Even supposedly non-conductive surfaces like laminated benchtops. There will likely be contaminants/water vapor film on all surfaces that make them slightly conductive. Put your palm flat on the destination surface for a couple of seconds. Then put the board down there.
Personally, I wipe the entire surface area with my hand, since 'insulating' surfaces can have acquired local charge concentrations.
2. When picking up bare electronics, always attempt to make first contact to whatever serves as a ground plane on the board. Metal frame, connector shells, ground point screw holes, etc.

If you can learn to think of everything around you (and yourself) in terms of static electrical charge retention characteristics, and develop correct movement habits, you don't need things like wrist straps, shoe discharge straps, anti-static benchtops, etc. But you do have to be sure you can never ever forget to do it right.

[free_electron]

Anti-static procedure: Step one, understand what static is, -snip- edited for the quote

All of the above. Terrahertz is spot on, but short of complete.

People keep making mistakes using ESD mitigation and prevention equipment (wriststraps, bags, mats) because they don't understand the problem nor the failure mode, nor the tools and their limits.

Here is the problem, how to solve it , and what to use and how to use it.


Static electricity is not dangerous. It is just an electrical field emanating from abunch of trapped electrons. The electrons are trapped on a non-conducting surface. Meaning they can't move. Not unless you give them a pathway to move. I can have a single pin of a super expensive chip sitting one
 inch from a 10 kilovolt charge.... nothing is going to happen.  Not unless i create a pathway for the electrons

If you give them a pathway to move a current will flow. How much depends on the number of electrons per square millimeter were trapped (the 'voltage') and the resistivity of the pathway.

In the example above : all other pins of that chip are floating. If i create a pathway a current will flow to 'charge' the chip to the same potential. That is sufficient to destroy it. The act of balancing the charge can kill. There needs not to be a closed loop !

Components are sensistive in two ways : the isolation barriers (the non conducting pathways) used in very small structures like in integrated circuits, can't hold such high strengts field, so you blast holes in em. So, the esd diodes in integrated circuits will trip , long before the field strength has been allowedto build. (Fields don't build instantaneously , you need to move a number of electrons to build up that field. The electron speed is limited (no, it is not lightspeed. )

Second way: while the electrons are moving (current) heat is generated in the resistanceof the pathways. Since these are very tiny , if the currentis high enough you will vaporise the small structures... Causing an 'open'.... At that point the field will build and strikethrough will happen.

The combination of both happens when you destroy a circuit with a static discarge. You blast the metal open first, the field builds and you get flashover second.

So. How do we solve this problem ?

By limiting the current in case equalisarion is necessary , or better, by preventing charge buildup.

There are three kinds of materials we can use

1 conductive : these are low ohmic and used to prevent charge deltas across a surface. Since they are conductive electrons will spread very guickly across their surface so no voltage delta is possible ( voltae delta is the field strentgh between two points on that surface.). Such materials are to be used as an outward shield ! Never as an inward shield. Since they are conductive: blast a field into them and the field will blast into the connected circuit , destroying it !

2 dissipative : these conduct , but very badly. In the order of hundreds of megaohm. These materials allow charge to 'leak away' controlled.

3 antistatic : these materials will not rrelease free electrons of themselves. You can store a charge on them ! A stored charge can be released, but the material will not create a charge by itself.

Point 3 needs clarification. It has to do with friction. Take two dissimilar materials, rub em together and you can knock off free electrons. Sweep the electrons in a pile and you build a field. Have enough of em together , give em a pathway and armageddon begins.
Animal fur and an amber rod are notorious for generation static charges.
Not all combinations work and some materials do not work at all, whatever you rub against them. Those materials are antistatic.

So how do we apply correct methodology ?

You wrap a sensitive device in a dissipative blanket first. Whatever outside charge now occurs will be dispersed very controlled. But, if the charge is high enough it may still cause problems ! Remember that it takes time to disperse charge in this material, so there is a moment where you can have a substantial voltage delta . This can still be catastrophic.

So ,you wrap the dispersive material in a conducting material. If you zap the conductive material, the charge there disperses very quickly. The dissipative material is instantaneously at the same potential everywhere, and it will leak electrons slowly to equalise with whatever is stored inside.

This is how those silvery metallized bags work. The inside is dissipative, the metal film is vapor deposited. Zap it and the dissipative film is immediately equipotentially charged and will balance itself slowly with what is stored inside. The pinkish bags with black lattice are similar in nature. The black lattice is carbon and in the order of 10 kiloohm. The pink stuff is dissipative.

Now, what do you use when ? Motherboards with sharp pins , holding a battery can be provlematic in the silver bags. Poke the pins through the bag and you short the battery in the metal deposit. So there the carbon lattice is safer.

The pinkish or blue-ish bags are dissipative.

True antistatic material is seldom used and is a specialty item for those situations where absolutely no pathway is to be present.

Given the above i will now explain how stupit it is to poke components in sheets of styrofoam wrapped in aluminum foil... You should be able to figure it out if you followed my explanation so far. Think about it and then read on to verify you understand it.


Styrofoam is notorious as a charge storage. You wrap this in a very conductive material. So you will balance the charge across the styrofoam. Poke in a chip and you fry the first pin that makes contact with the aluminum foil. Because all the stored energy now has a low conductive pathway (metallic) into the chip. In essence : the aluminum foil prevents a charge delt aon the styrofoam ... You are in essence protecting the styrofoam. Not the chip.... 

So the next time you go to your favorite shop and see chips poked i. Aluminum foil On top of styrofoam , laying in the little plastic drawers in metal racks ( those drawers build charge like hell everytime you open and close them)
: slowly back out of the room and while passing the threshold of the door tell the shopkeeper to read EEVblog and point him to this article.



Now, on the whole thing about grounding. There is really no need for that. As long as you do not create a low ohm pathway to equalise a field no harm will be done.

I can have a superexpensive chip in my pocket, don my chainmail labjacket and let the teslacoils zap away at me. That chip will have no damage. Why ? Because it and myself are both at a million volts. There is no voltage delta between me and the chip, no charge can move. Nothing happens. We (me and the chip) both are lifted simultaneously to a million volts.

So, on a bench : simply equalise yourself first to the antistatic bag by touching it , wait a few seconds, then grab the board. I can do this inside my cage at a million volts above ground. No problem.

So why do we tie all our equipment, bench mats to the power grid ground then ? Well.. Because of the tendency of us ,meatbags, to walk on it , sit on it or otherwise be in contact with it. And us meatbags are sometimes not conductive enough , or we hold a charge if we walk on rubber shoes , and have a tendency to stick our appendages where they don't belong ...

Pure practicality. If i walk barefooted on my concrete garage floor i dont need to put on the wristband. I wont build a potential delta between me and the benchtop mat(that is connected to the ground, or copper rod pounded into the foundation. The concrete is moist enough to be dissipative. If i wear my rubber flipflops ... Problem... I will build charge differential.... Especially when wearing my silk shirt rubbing abains the faux-leather coating of my otherwise non-conductive chair.

But since her in california i always wear short sleeved shirts and my arms touch the bench mat: no problem. I am dissipating my charge.

So it all depends. Think about what you are doing , where charges can build, and how you make sure there is only a dissipative pathway possible to balance them out.

Capice ?

[TerraHertz]

If you want to understand the Zen of static electricity, look up Wimshurst machine.

[TerraHertz]

free_electron chose his name with great care. The only thing I don't agree with is the bit about al-foil wrapped styrofoam. Yes, styrofoam is a terrible generator and holder of static charges when rubbed. But so what, the al-foil is a conductive sheet. You touch the edge of the sheet first (for inserting or removing chips), and now all the chips (and their pins) are the same potential as you. Even if a pin doesn't make perfect contact with the foil on inserting, it's still only in contact with a small volume of foam, and so low total quantity of charge. Besides, the foam was all right next to the foil for a while anyway, so charge minimized. Another factor is that it's not all about contact, but rather minimization of local electrostatic fields. Which the foil does very well.

I've used the 'metal foil on styrofoam sheets' on a large scale to store CMOS chips (for eg the 4000 series, which is notoriously easily damaged by static discharge) with never any problems.

Anyway... I came here to post this - a fine example of how NOT to practice good anti-static technique:
http://motherboard.vice.com/blog/this-sexed-up-guide-to-building-a-pc-is-simply-the-worst
Also, how not to dub dialog.
The clip has other redeeming points though.

I've heard some people claim minimizing clothing is essential to avoid static. Sadly it's not really true.

[free_electron]

The problem with the Styrofoam is the following :

Let's say the Styrofoam gets charged in a specific spot due to friction. I don't care where that spot is. Since that spot touches the aluminium foil , the foil will redistribute the charge all over. So there will be no voltage delta across the foam, but the entire thing (foam + aluminum) still holds a charge !

Grab a chip and try to insert it into the aluminum. No matter how hard you try , only one pin will make contact first , piercing the aluminum. That is the pin that gets the full charge of the injected in it through a very good conductor... so there is no current limitation !

I agree that, if you touch the aluminum foil first with your left hand and you hold the chip in the palm of your right hand, making sure to touch all the pins, no harm will be done as you use the high resistance of your body to level the charge differential. IF you just hold the chip by its body and plonk it in : disaster !

I've often seen in electronics stores : the guy takes a tube of freshly bought chips , pops the pin and then proceeds by simply letting them slide in the aluminum foil coated drawer ... I can just hear the electrons crackling...

The problem with ESD is like I said : people don't understand it and proceed to apply techniques they don't understand in a completely wrong way.
It ends up being 'cargo cult science'. They see someone do it and mimic it, using the wrong practices and wrong tools / materials. and it all goes to snot.

That is also the reason we have those stupid rules about wristbands, esd clothing , shoe straps , shoes , benches etc.. it is being dumbed down to the point you don't need to understand anything. just wear the antistatic frock , wristband , shoe , use the correct chair and bench mat , plug yourself in and nothing will go wrong. You don't need to know how it works, just follow procedure.

[c4757p]

My 2c on the foil-on-styrofoam: I use it all the time with very sensitive parts and I've never had a problem - but that's because I'm careful. The foil aids in dissipating charge, it's not a magic charm against it like many people think.

Everyone seems to think static charge is the problem. To me, that's like thinking you die from altitude or speed. No, you die when you very suddenly lose them.

First of all, I don't like the dissipative tubes, because they're often only a very tiny bit conductive, and people are tempted to just grab them and go. I always make sure to leave the closed tubes on a grounded surface for a few minutes to ensure that the entire tube and its contents are all at ground potential. Then, if I want to put chips from the tube into the foam, I ground myself, then remove the chip and hold it in my hand so that I'm touching all the pins. Then I take the block in the other hand, and then I know that the entire foam/foil block as well as the entire chip are equipotential and I can insert the chip without worrying about it.

Once they're out of the damn tubes, it's easier, because when I'm working I always try to maintain everything near ground. I work over a grounded antistatic mat, and circuits themselves are grounded by the oscilloscope that's typically hanging off some test point or such. I just ground myself, grab the block, and remove the chip from it; I don't have to worry that anything has been floating around and picking up charge.

[free_electron]

Tubes are dissipative , or in case of the black ones conductive above 100K.
You only need a few seconds to charge-balance.

The time it takes to pop the pin (or plug. the pin is the little plastic thingie at the end prevent the chips from falling out)  is enough to have it equalize. You don't need minutes.

ESD protection can be summed up in 1 rule : Limit the current between two objects that have a charge differential.

Poking pins in a lump of aluminum foil is therefore a no-no. Poking pins in a lump of carbon is not a problem. it's that simple. And while I agree that you can work around by putting the tube in contact with the aluminum foil first and , before taking chips out of the aluminum foil, touch the foil first before grabbing the part this is all error-prone. IF you do it while you understand what you are doing. fine. But the problem is that many people 'learn' by seeing... and in this case the visual aspect is misleading...
that is why iw ill never do stuff like that around other people, especially 'newbies' (I don't like that term.. i'd rather call it the uninitiated) because of the risk of setting a huge bad example. We can do without more of that stuff. the internet is already full of arduino-engineers , soon we'll have tinfoil engineers...

Styrofoam with aluminum around it is cause for eye-brow raising in my booklet.

[rsjsouza]

Back in the day the black dissipative sponge was unheard for hobbyists, therefore I became a big fan of Aluminum foil for MOS devices. Initially I simply wrapped it around my 4000/74C/74HC devices without much thought, but over the years I learned what free_electron mentioned: let the device and the foil sit for a few seconds on a dissipative grounded mat before wrapping one around the other (yes, the body is grounded through a wrist strap as well).

Obviously that this method is not viable for production environments, where zillions of devices are assembled every minute and failures quickly escalate in cost (all perfectly valid points mentioned by free_electron and TerraHertz). But for hobbyist use this is the most cost effective solution I found.

I used styrofoam + foil for some time, but the one issue I had is that continuous re-insertion causes the foil to retreat from the holes on the styrofoam, thus leaving floating pins.

[c4757p]

I used styrofoam + foil for some time, but the one issue I had is that continuous re-insertion causes the foil to retreat from the holes on the styrofoam, thus leaving floating pins.

I should have clarified: I'm not actually using styrofoam, this is a more flexible sort of foam that was initially used for packing (couldn't tell you what kind), and when I wrap the foil around it, I also apply a very thin layer of adhesive between the foam and foil. It still retreats a little bit, but only from the 'wedge' effect of the angled pins on factory-fresh DIPs, it still makes contact with the back sides of the pins.

[JoeyP]

I won't even place an un-powered motherboard on its static bag. I've measured some static bags and found them to be close to a dead short. That means the CMOS backup battery can be discharged by simply leaving the motherboard sitting on top of the static bag with no other connections.

[c4757p]

Those are some cheap-ass antistatic bags then... Even the ones that DigiKey wastes in massive volume by using them to package resistors and switches are properly dissipative.

[free_electron]

oh the bag is conductive allright. once you poke a hole through the foil and touch the metal deposit.
never place mobo's on those metallized bags. just because of the battery.

[c4757p]

Is there truly a fully conductive layer in them? I swear to god, I remember probing them for that a long time ago to see if that was the case and not getting anything.

[David_AVD]

I just did some experiments to measure the resistance of two types of "anti-static" bags.

The first type was a metallised type.  Using a multimeter, I measured infinite resistance on the inside and outside surfaces.  I then poked the probes through the bag and.... still nothing.  Even dragging the probes over the surfaces to dig into it has zero effect.  There was nothing I could do to get a reading.

The second type was the clear type with a grid of fine and coarse lines printed on the outside.  Using a multimeter, I measured infinite resistance on the inside surface.  The outside surface did give me readings though;

From end to end of bag (about 200mm) I measured 100K.  When the probes were placed as close as possible to each other (without touching), I got a reading of 20-30K on the fine lines and 3-4K on the thicker lines.

Poking the probes through the bag got some readings, but very dependent on exactly where the probes hit and always a relatively high value (10's to 100's of K).

So, it appears that the metallised ones are no issue at all?  Even the gridded bags had such a high resistance that I can't see how a MB battery would be damaged.  The grid *may* have some effect on a running MB though and I certainly wouldn't power up a mains PCB on it.

[JoeyP]

I just did some experiments to measure the resistance of two types of "anti-static" bags.

The first type was a metallised type.  Using a multimeter, I measured infinite resistance on the inside and outside surfaces.  I then poked the probes through the bag and.... still nothing.  Even dragging the probes over the surfaces to dig into it has zero effect.  There was nothing I could do to get a reading.

The second type was the clear type with a grid of fine and coarse lines printed on the outside.  Using a multimeter, I measured infinite resistance on the inside surface.  The outside surface did give me readings though;

From end to end of bag (about 200mm) I measured 100K.  When the probes were placed as close as possible to each other (without touching), I got a reading of 20-30K on the fine lines and 3-4K on the thicker lines.

Poking the probes through the bag got some readings, but very dependent on exactly where the probes hit and always a relatively high value (10's to 100's of K).

So, it appears that the metallised ones are no issue at all?  Even the gridded bags had such a high resistance that I can't see how a MB battery would be damaged.  The grid *may* have some effect on a running MB though and I certainly wouldn't power up a mains PCB on it.

I don't think thats true *at all*. I don't think you should make assumptions about all bags based on testing exactly two samples. There are many types available, and many manufacturers. I have definitely found some to have conductivity in the low (<10) ohms range using very basic probe measurements.