Proper ESD Workspace Grounding Questions

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Nate Thibault @pinkfloydeffect

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Posted: Oct 2, 2018

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Proper ESD Workspace Grounding Questions

I work for a chitty repair shop and I am trying to set the story straight here on proper ESD safety procedures. Our main tech bench has the grounded mat on it, but we have a few other work areas that do not. Those other areas are used with these blue mats you see in the photo which do not have any grounding lead but I think the chinese package said they were ESD safe. I can not see how they would be very protective, as a minor of fact I picked one up off one of the work areas not long ago and you could hear snapping as I peeled it off a laminate surface. For at home purposes, I bought this red travel mat (with pockets at the top which I do not understand what you would use for?) but I still like the blue mats so I am wondering if the blue mat would isolate the device from being properly grounded through the red mat though?? I do not use a wrist strap at work but I always touch or lean on the grounded mat I am working on. If I have to wear one I would rather have it on my ankle to be honest.

On a side note I am looking to start a business working out of a commercial high top van and I need to know how you would go about grounding a mat on a desk in the van if it is isolated from the ground with rubber tires? Thanks

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jayeff @jayeff

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Posted: Oct 2, 2018

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Hi,

Just wondering if the blue mat is made of a material that has a high resistance to the discharge of static electricity from either you or the device which is placed on it.

The pockets in the red mat are probably there to hold tools etc. That way you can roll up the mat with the tools enclosed and move onto the next place that you’re working at, ready to go when you unfold the mat.

I think that the person repairing the device should be grounded as the body can build up and store static electricity and this static build up needs to be discharged before working on ESD sensitive devices. This static build up can be produced by just walking across different floor surfaces, e.g. walking across a synthetic carpet is a good way to build up static in the body.

As for a solution for a van, if you ground the mat to the van’s chassis it will be at the same earth potential as the van and provide a path for the static to discharge to. You could also use a strap to ground yourself to the chassis as well then you and the mat will be at the same potential with respect to the same earth, (-ve side of van battery) If you want you could always connect an anti static strap under the van that touches the ground. It’s a rubber strap with a metal insert. They used to be quite a common sight. It was mainly used to help prevent people getting “zapped” when touching car doors to open or unlock.

Just my $0.02 worth

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Instead of thinking ground as in earth ground think of it as a common point of discharge. As an example the ISS is free floating in space so where is ground? Ground there is the metal body frame of the ship and all of the segments are electrically bonded to each other so no matter where you are within the ISS touching the ship's frame is ground. Your van is the same! If all of the parts, tools and your self are electrically touching the metal frame of the van then you are at the same electrical potential.

The issue with anti-static materials that are placed on each other is it does take some time for the discharge to take place depending on how much contact and if the surfaces have enough pressure to make good contact. So don't be to quick to pick something up give it a good minute or two.

Your blue trays may need a bit of treatment to be useful! Take some plain liquid soap and mix it with some water 1 to 10 and fill a spray bottle to make antistatic spray! Spray the tray after washing it and then letting it dry every week or so. This will make it truly anti-static. You can also use this spray on other surfaces as well.

Oct 3, 2018 by Dan

I am unsure of the composition of the blue mat but the package said “ESD Safe”

With a mat the size of the red one I always end up leaning on it, thus discharging my body.

Does grounding to the van chassis have to do with the conductive metal mass of the vehicle or the battery its grounded to? I was not aware of the rubber coated metal strap you can get but I do remember the days when ambulances used to drag an array of metal chains I assume for the same reason?

Very interesting advice on the anti-static spray, I assume this must be based on the principle of leaving a thin layer behind?

Oct 4, 2018 by Nate Thibault

Hi,

Unless you're leaning on the red mat with bare skin or touching it with your hands, it will not be as effective as a strap attached to the skin. Also see comment in my answer above re carpet if you wish to have "warm feet" whilst working in your van ;-)

It's about all the surface areas being at the same electrical potential as each other.i.e. if the red mat was not connected to the chassis it would be at a different potential with respect to the chassis and also to you if you weren't connected to the chassis either. Therefore the possibility exists of static discharge between surfaces having different potentials.

I believe that because the chassis is tied to a -ve potential from the battery any static will try to discharge to that and therefore go through the path of least resistance i.e. big mass of metal in the chassis so it's probably both. Of course I may be totally wrong about that.

Oct 4, 2018 by jayeff

I'm pretty sure the question of grounding in a van has been brought up before. I would spend some time searching within the iFixit Forum.

As for those blue work mats, I have one of those (it's gray instead) and while practical, I too found that they generate a ton of static electricity. So I stopped using it. Perhaps there are different materials and quality levels but when you order from China, you never really what you get.

Oct 5, 2018 by Minho

@jayeff - Agreed! The elbows on the mat is not a good solution you need the wrist strap and have both the mat and strap tied to a good bare spot of the vans frame.

Correct! The same charge (electrical potential).

It makes no difference about the vans battery which is why the ISS is a good example as its free floating in space ;-} The Van is no different.

Now if you had someone enter the van which had a charge buildup and touched you while you had your hands on something sensitive then you could have zapped it. So don't pat someones back as a hello ;-} You also want to discharge your self before touching anything sensitive and the container holding the sensitive chips should first touch the mat before you open it.

The spray bottle of soap will work as a static dissipater! So spraying the carpet or even the tray would reduce the risk. Sadly, it does wear off loosing its effectiveness. So you need to re-do it often.

I like the carbon filled trays (black) and I use some closed cell pink antistatic foam to press the screws into to keep them from rolling away and I can see them more clearly than the blackness of the tray.

Oct 5, 2018 by Dan

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Instead of thinking ground as in earth ground think of it as a common point of discharge. As an example the ISS is free floating in space so where is ground? Ground there is the metal body frame of the ship and all of the segments are electrically bonded to each other so no matter where you are within the ISS touching the ship's frame is ground. Your van is the same! If all of the parts, tools and your self are electrically touching the metal frame of the van then you are at the same electrical potential.

The issue with anti-static materials that are placed on each other is it does take some time for the discharge to take place depending on how much contact and if the surfaces have enough pressure to make good contact. So don't be to quick to pick something up give it a good minute or two.

Your blue trays may need a bit of treatment to be useful! Take some plain liquid soap and mix it with some water 1 to 10 and fill a spray bottle to make antistatic spray! Spray the tray after washing it and then letting it dry every week or so. This will make it truly anti-static. You can also use this spray on other surfaces as well. — Dan
I am unsure of the composition of the blue mat but the package said “ESD Safe”

With a mat the size of the red one I always end up leaning on it, thus discharging my body.

Does grounding to the van chassis have to do with the conductive metal mass of the vehicle or the battery its grounded to? I was not aware of the rubber coated metal strap you can get but I do remember the days when ambulances used to drag an array of metal chains I assume for the same reason?

Very interesting advice on the anti-static spray, I assume this must be based on the principle of leaving a thin layer behind? — Nate Thibault
Hi,

Unless you're leaning on the red mat with bare skin or touching it with your hands, it will not be as effective as a strap attached to the skin. Also see comment in my answer above re carpet if you wish to have "warm feet" whilst working in your van ;-)

It's about all the surface areas being at the same electrical potential as each other.i.e. if the red mat was not connected to the chassis it would be at a different potential with respect to the chassis and also to you if you weren't connected to the chassis either. Therefore the possibility exists of static discharge between surfaces having different potentials.

I believe that because the chassis is tied to a -ve potential from the battery any static will try to discharge to that and therefore go through the path of least resistance i.e. big mass of metal in the chassis so it's probably both. Of course I may be totally wrong about that. — jayeff
I'm pretty sure the question of grounding in a van has been brought up before. I would spend some time searching within the iFixit Forum.

As for those blue work mats, I have one of those (it's gray instead) and while practical, I too found that they generate a ton of static electricity. So I stopped using it. Perhaps there are different materials and quality levels but when you order from China, you never really what you get. — Minho
@jayeff - Agreed! The elbows on the mat is not a good solution you need the wrist strap and have both the mat and strap tied to a good bare spot of the vans frame.

Correct! The same charge (electrical potential).

It makes no difference about the vans battery which is why the ISS is a good example as its free floating in space ;-} The Van is no different.

Now if you had someone enter the van which had a charge buildup and touched you while you had your hands on something sensitive then you could have zapped it. So don't pat someones back as a hello ;-} You also want to discharge your self before touching anything sensitive and the container holding the sensitive chips should first touch the mat before you open it.

The spray bottle of soap will work as a static dissipater! So spraying the carpet or even the tray would reduce the risk. Sadly, it does wear off loosing its effectiveness. So you need to re-do it often.

I like the carbon filled trays (black) and I use some closed cell pink antistatic foam to press the screws into to keep them from rolling away and I can see them more clearly than the blackness of the tray. — Dan

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