Author Topic: Ooops. Silicone soldering mat.  (Read 3803 times)

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Offline paulca

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Ooops. Silicone soldering mat.
« on: November 28, 2017, 06:41:36 pm »
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.
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Offline cdev

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Re: Ooops. Silicone soldering mat.
« Reply #1 on: November 28, 2017, 06:51:01 pm »
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?
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Offline jmelson

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Re: Ooops. Silicone soldering mat.
« Reply #2 on: November 28, 2017, 07:52:37 pm »
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
 

Offline nanofrog

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Re: Ooops. Silicone soldering mat.
« Reply #3 on: November 28, 2017, 08:16:59 pm »
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).
 

Offline alank2

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Re: Ooops. Silicone soldering mat.
« Reply #4 on: November 29, 2017, 01:47:47 am »
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.
 

Offline paulca

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Re: Ooops. Silicone soldering mat.
« Reply #5 on: November 29, 2017, 07:45:40 am »
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.
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Offline cdev

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Re: Ooops. Silicone soldering mat.
« Reply #6 on: December 22, 2017, 02:49:24 am »
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.
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Offline eKretz

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Re: Ooops. Silicone soldering mat.
« Reply #7 on: December 25, 2017, 07:34:55 am »
Not sure why you guys would buy anything other than a legit ESD safe mat. They aren't very expensive.
 

Offline RoGeorge

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Re: Ooops. Silicone soldering mat.
« Reply #8 on: December 25, 2017, 11:37:49 am »
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.
« Last Edit: December 25, 2017, 11:43:49 am by RoGeorge »
 

Offline nanofrog

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Re: Ooops. Silicone soldering mat.
« Reply #9 on: December 25, 2017, 09:28:22 pm »
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.  :o  :-DD
 

Online sleemanj

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Re: Ooops. Silicone soldering mat.
« Reply #10 on: December 25, 2017, 10:23:34 pm »
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.
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Offline tooki

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Re: Ooops. Silicone soldering mat.
« Reply #11 on: December 26, 2017, 12:33:38 pm »
They make antistatic sprays specifically for electronics, for use on plastics (surfaces and textiles).
 

Offline jh15

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Re: Ooops. Silicone soldering mat.
« Reply #12 on: December 28, 2017, 12:37:40 am »
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.
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Offline Nerull

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Re: Ooops. Silicone soldering mat.
« Reply #13 on: December 28, 2017, 04:57:10 am »
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.
 


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