Ooops. Silicone soldering mat.

[paulca]

Bought a silicone soldering mat off ebay.  Was hoping to use it for working on, soldering on, cutting on etc.

It lasted about 5 minutes until I binned it.  Why?  Just lifting it off the desk again and it crackled and fizzled and when I held it up to my head it lifted my hair on end.

That and the knife when straight through it while ironically cutting some anti-static foam for my parts box.  Just hoping that none of the chips got fried while I was putting them into said anti-static foam.

So, the mat is not anti-static, it's actually a static generator!  I've tried ground it on radiators, PSU case, the bathroom taps, but it still holds the static. 

FAIL.

[cdev]

They seem to be popular but you may well be right.

Is there a way to test its likelihood of causing ESD damage in real use scenarios?

[jmelson]

They seem to be popular but you may well be right.

Is there a way to test its likelihood of causing ESD damage in real use scenarios?

The OP already DID!  He says it lifted his hair!  That's serious electrostatic charge, so the thing is a very good insulator, and maybe also has a large triboelectric potential.
You really want the opposite of both of these for use around ESD sensitive parts.

Jon

[nanofrog]

FWIW, most proper rubber ESD mats are made from nitrile butadiene rubber rather than silicone (NBR, though commonly referred to as nitrile rubber). Although it can be cut or punctured, it's tougher to do so. Resistant to most solvents as well.

One source that clearly ID's the rubber used would be Hakko.

Neoprene is what's used in the single layer ESD mats that can take the heat (more familiar with this used for conveyor belts or welding in ESD sensitive applications).

[alank2]

I use a silicone mat - it was cheap.  I found it wanted to generate static when moved away from the table so I double stick taped it down in 4 corners.  Haven't lost or damaged anything yet when using it.

[paulca]

I thought about seeing if I could measure it with a DMM, then I realised static discharge can be measured in kilovolts and I like my meter.  At those voltages it might not be ESD safe itself.

[cdev]

Okay, lets have an experiment. I just received a brand new cheap silicone rubber mat. Its the most common one, it cost me around $5 . Its wrapped in a polyethylene plastic bag and it appears to be clinging but that may just be because its still sealed. How can I ascertain if its ESD vulnerable in a typical use situation (sitting on a wooden table now but the rubber mat will probably end up next to my esd mat and sometimes on top of it.) 

I am going to use it for soldering small parts, to contain them if they fall.

What can I test thats a realistic determinant of danger?
 Its kind of dry here now so this is a good time.

[eKretz]

Not sure why you guys would buy anything other than a legit ESD safe mat. They aren't very expensive.

[RoGeorge]

Bought a silicone soldering mat off ebay.  Was hoping to use it for working on, soldering on, cutting on etc.

It lasted about 5 minutes until I binned it.  Why?  Just lifting it off the desk again and it crackled and fizzled and when I held it up to my head it lifted my hair on end.

That and the knife when straight through it while ironically cutting some anti-static foam for my parts box.  Just hoping that none of the chips got fried while I was putting them into said anti-static foam.

So, the mat is not anti-static, it's actually a static generator!  I've tried ground it on radiators, PSU case, the bathroom taps, but it still holds the static. 

FAIL.

Silicone mats had never been antistatic, and they are not supposed to be antistatic, nor good for cutting. The antistatic and pierce resistant ones are rubber based, not silicone.

The silicone based mats are used for their excellent thermal isolation, so they are good for hot air rework without a preheater and without burning the workbench. They are also great electrical insulators, so they will easily build static charges on them, but being such a great electrical insulator, the charges will stick but will not flow, so their is no danger for a big built charge to flow between a part and the mat.

That is why a silicone mat won't fry the chips with static electricity.

[nanofrog]

Silicone mats had never been antistatic, and they are not supposed to be antistatic, nor good for cutting. The antistatic and pierce resistant ones are rubber based, not silicone.

The silicone based mats are used for their excellent thermal isolation, so they are good for hot air rework without a preheater and without burning the workbench. They are also great electrical insulators, so they will easily build static charges on them, but being such a great electrical insulator, the charges will stick but will not flow, so their is no danger for a big built charge to flow between a part and the mat.

That is why a silicone mat won't fry the chips with static electricity.

In regard to ESD or cutting, you're correct. But silicone is rubber (thermoset; heat = catalyst to convert the resin to final product while in it's mold; aka vulcanization). Meaning they won't melt once formed (they disintegrate/burn instead).

And although silicone can take the heat, it's not ESD disipative. It's also more vulnerable to cuts/punctures vs. other materials, such as nitrile rubber.

Nitrile is disipative (spreads over the surface), but it also needs a path to ground to be of any use for electronics. As you don't want this path to be as fast as possible, the bottom layer is carbon filled. Which acts as a resistor between the mat and safety earth/ground (slows down the rate of discharge).

I know, it's likely too much information, but the forum is full of people interested in the details.   

[sleemanj]

Spray with some diluted fabric softener and let dry maybe?  I don't know the science behind it, but it's long been told to impart static dissipative properties to  otherwise non-disspative insulators.

[tooki]

They make antistatic sprays specifically for electronics, for use on plastics (surfaces and textiles).

[jh15]

slow discharge is a good thing.

I was involved (e.g. had to ruin a 100 mile a day road bicycle tour I trained for all summer weekend for a horse and pony show to set up our plant for esd protection the next Monday).

New to me in 83 was the slow discharge rate item. Made sense to me, my boss (I think, or he worked or knew employees in  dynamite factory stuff), and they had been concerned forever for this. Also medical anesthesia stuff.

sure, a copper bench top will surely discharge esd, very quickly. And make a big disharge spike to your stuff.

[Nerull]

Proper ESD mats do have a slow discharge - that's what static dissipative means. When mats are tested for compliance they are tested for both maximum resistance and minimum resistance. The entire point is to dissipate charges at a rate that will minimize damage to electronics.

[Dokroma]

Posting here because I just tried out my mat and the thing makes my hair stand, literally. It's a blue mat I got from Jaycar. Is it dangerous to solder on it? What could I use then to protect my wooden table and also not fry my electronics?

[paulca]

Posting here because I just tried out my mat and the thing makes my hair stand, literally. It's a blue mat I got from Jaycar. Is it dangerous to solder on it? What could I use then to protect my wooden table and also not fry my electronics?

My understanding is that these silicon mates are not appropriate for soldering electronics on.  The silicon is a good insulator, so any static or electrical fields, just build up on it's surface until you or your electronics provide them a path to a lower potential.

I don't know what charge the mat would hold and what the effect of it would be if it, say, discharged through your circuit board to your grounded soldering iron, but I doubt it would be good for ICs etc.

I believe the best solution for static discharge is a conductive mat which has a ground clip to earth it.

[radiolistener]

I have blue Chinese silicone mat S130 from aliexpress.
I used it for sensitive MMIC LNA replacement and soldering other components. Works ok.

[Gediminas]

Just made video on this topic.

[Jwillis]

Silicone elastomers are insulators and can build up static charge. The rate and charge is dependent on the humidity of the air. The dryer the air the more static charge can build.
A true ESD mat is not an insulator but alllows discharge to earth ground keeping the Mat a a Zero potential.The wrist strap keeps the user at the same potential as the Mat and earth ground. But both are only as good as the earth connection.
Antistatic sprays are bandaids that can't be trusted since atmospheric conditions change constantly.
True ESD mats are really not that much more expensive than a silicone soldering mat and are well worth the certainty over over the gamble of band-aid solutions.

[aduinstat]

Yeah, not conductive at all. However, the mat was advertised as "Antistatic" and not "Dissipative", and the pink plastic also gave a similar measurement.

[shapirus]

Just measured mine, same generic blue silicone (by the feel of it) mat as on the photo above. No conductivity at 2500V. Haven't done the hair test, as it's full of soldering stuff lying on it now.

Also tested a dozen of "antistatic" plastic bags that they ship components in. No conductivity at 2500V in any of them, totally dielectric. Most came from aliexpress, one was from an ASUS video card. The only one I found that is actually conductive is a bag that an MSI motherboard came in, and it has conductive stripes in a crosshatch pattern with the rest of the surface looking like a usual clear (and non-conductive) PE.

I wonder if that's the right way to test the "antistatic" bags. I imagined they would have to be conductive. They are also not any different from the regular transparent plastic bags in the hair test. Weird.

[tooki]

The pink or blue antistatic bags simply don’t generate any static charge, but they aren’t conductive. The silver-gray bags are conductive, but they are laminated and I’m not sure which layer is conductive, so I am not sure how to properly test them.

[shapirus]

The silver-gray bags are conductive, but they are laminated and I’m not sure which layer is conductive, so I am not sure how to properly test them.

I tested the silver-gray ones. Good catch about the layer: I tested the outer layer, oops.

The meghommeter is already stowed away, so I did a quick test with a Brymen 869s in the nanosiemens mode. ASUS bag, inner layer: ~0.2 nS (5 GOhm) with the probes ~1 mm apart. So somewhat conductive. A random bag from aliexpress: still no conductivity on either layer.

[EPAIII]

I know that everybody is going to shout me down on this, but I think the need for anti-static mats is highly overrated. I have worked in electronics for well over 50 years and have never had a single part become damaged from static.

Anti-static measure #1 is to not work in a room with a carpet.

Anti-static measure #2 is that anti-static measure #1 is enough.

If you are really worried, then have a grounded plate on the workbench and touch it before working. Once an hour or once each time you sit down is more than enough.

And consider, electricity flows from - to +. And a grounded electrostatic mat is ONE END of that circuit. If you have a static charge and start to pick up a part on that grounded mat, then the charge will leap from you, to the part, and into the mat. WHY provide that path by installing the mat?

And if you are going to insist on a static mat anyway, the very last place on earth where I would buy one is AliExpress. For Pete's sake, go to an established electronic supplier. You know, one who charges full price for something that actually works.

[RoGeorge]

I've bought a mat from Aliexpress, in bulk, to cover all the width of the workbench.  Dark green, rubber based, so antipiercing, anticutting, heat resistent (can heat and roll a blob of solder on it without any damag, also antistatic, with a grounding bracelet and all the fuss.  Well, never used the antistatic things, of course.

In practice I still put a big sheet of white paper, just like before buying the mat, this time on top of the mat. 

The white paper gives a much better visibility for parts and tools spread on the bench, and I don't spill solder on the bench anyway.  Another downside for the mat is that is has to be swiped to clean, while a a paper can be lifted, then tilt all the scraps into the waste bucket, plus the paper can be tossed away when it becomes too dirty, and you'll have a new clean surface, while a mat will remember forever all the stains and scratches.

My advice is to just lay down some white paper on the bench.  Unless you repair boat anchors, no mat is needed.  Ese a white sheet of paper.  As for a supply of big and thick white paper, use the back side of the pages removed from those large wall-calendars.