serious cleaning of ESD matt? - Page 1
Forum section: electronics / general

author: coppercone2
author_rank: Super Contributor
timestamp: August 17, 2018, 07:39:55 pm
content: My ESD mat has been through hell, including burn marks from running a impromptu temperature calibrator. It basically looks like it has military camoflage on it with loads of streaks and shit. It is the very tough dual layer rubber kind, not the foam stuff.. the rubber is textured like a topographical map.Are there any ways to improve its appearance? The only thing I can think of is to scrub it down with something like gojo mixed with alcohol or acetone (walnut shell soap), that is how I handle 'rubbery' grips for power tools.I don't want to throw it out because a small sheet of it was like 70$, but it just looks like pure ass. It is like 5 years old.

author: GreyWoolfe
author_rank: Unknown
timestamp: August 17, 2018, 09:59:37 pm
content: There are commercial products for that. I have some, but can't remember the name. I borked the spray bottle it was in and am now using a no name spray bottle. Alcohol will dry out the mat. Not sure what acetone will do, might not be good either.

author: coppercone2
author_rank: Super Contributor
timestamp: August 21, 2018, 12:51:02 am
content: Ok I tried to use maguires ultimate compound and GOJO mixture on it, with a rotary polisher, after I pressure washed that shitIt went to about a 1/10 to a 4/10.The backside seems to have OK conductivity still. The top blue side of hard rubber is kinda brighter now, but I wonder if I can brighten it up with hydrogen peroxide. I can't do anything about the burn mark that charred it to the other side in the middle of it but at least now you can kinda see the SMD components that fell of your project.When I removed it off my work bench I felt like someone pulled a fucking bullet out of my head.What a piece of shit. I can't imagine what the table would look with out it, it already practically looked like little colonial marines had a fire fight with little xenomorphs on it. It looked like you pulled it out Hadley's Hope, after the melt down. Fucking weird discolored goo shit that looks like acid burns, acid burns, flux, burn marks, puncture wounds....I need a bigger lab so I can have a separate area for using glues and doing cleaning. And another mat that lays over the main protective one for soldering.I also wonder if I can pour a bunch of liquid electrical tape ontop of it and do a peel like you do for facial whiteheads, that stuff is actually really good at pulling off surface contamination. I really don't wanna spend 100$ on another one.Is there any way to restore the color? I don't care if the performance is somewhat degraded because I am sure its already shit. I can measure it with my electrometer and a 5lb weight afterwards.I get a gradient from the aqua it was to a kinda olive drab stain on the aqua.Maybe I can sand it and fuse it back togethe with carbon disulfide vapor? I have some and I don't think any other solvents will really do much to rubber. I don' treally understand how the conductivity works, do you have to 'exfoliate' it or something to avoid a seal of dielectric forming on it, or is the conductor uniformly mixed into the blue rubber top so even if you melt it it remains conductive? Does anyone know how this barely conductive rubber actually works? I kinda doubt they do anything but pour it into a mold. I don't see why I could not sand the surface to bring out some color then smooth it out again with polish or solvent polish...I know everyone is gonna say buy a new one but I really don't wanna spend that kind of money on a new dubious precautionary measure (read all the fights about how 'useful' these are), I already felt like I was putting a gun to my head buying it in the first place.

author: floobydust
author_rank: Super Contributor
timestamp: August 21, 2018, 01:13:05 am
content: Silicone ESD mats are very tough but very hard to clean. They seem to absorb things easily.I use IPA or Fantastic to clean them, and live with the schrapnel marks.Sometimes Manufacturing spills chemicals or glue on a mat and pretty much kills it.Vinyl ESD mats, just toss them out.

author: coppercone2
author_rank: Super Contributor
timestamp: August 21, 2018, 01:14:49 am
content: Quote from: floobydust on August 21, 2018, 01:13:05 amIs there any reason I can't sand and vapor polish it? I don't think its silicone, I think its some kind of rubber, It does not feel like silicone. It's not those foamy cheap ones either, its textured rubber, it smelled like car tires when I got it, and its very durable compared to all the other types of mats that I have tried.I had to leave it on a hot greenhouse type area for a week before it smelled good enough to bring indoors. A 4x2 foot section of it cost like 90$.I think most people have these smooth blue ones that are pretty soft, which have some kind of backing, this one feels like the mat you put on the floor of a car. Both the backing and the top feel to be made of the same material.Is it some kind of special silicone? It smelled like sulfur. Don't renember where I got it.The texture is random but if you run a stiff card across it fast you will hear a 'zip' noise, it kind of looks like a topographical map. The bottom is smoother, without the ridges, and kinda looks woven almost.I thought to use a buzz sander (wet) on it from 220 grit to 2000 grit and then compound polish it and maybe do the carbon disulfide vapor exposure to solidfiy the surface.

author: floobydust
author_rank: Super Contributor
timestamp: August 21, 2018, 01:31:02 am
content: I use the soldering iron test, a quick touch (end) tells me what the mat is made of. Silicone takes most soldering heat without melting, and blue vinyl is dead melts right away. Rubber stinks bad enough.I find the mats are a sandwich with a top layer of dissipative (high R) and middle layer of something black and highly conductive, ~100R end to end, but can't really take much heat.It's OK to sand and polish it, the material is conductive through and through.I hate vinyl mats, they don't last but are cheap so people use them.Another engineer I work with had enough and uses a sheet of aluminum now.

author: coppercone2
author_rank: Super Contributor
timestamp: August 21, 2018, 01:45:47 am
content: I thought the idea was that you did not want a spark to form between the part and the work surface, since a discharge would be high peak current. Did he increase the value of the coupling resistor? How is RF current handled? The resistance between the blue stuff and the black stuff is in the terraohms I think, and the coupling resistor used is 1Mohm. I don't really know what a 1meg resistor looks like at the high frequencies involved in ESD discharge, I thought the idea was similar to an oscilloscope probe wire/carbon composition resistor with distributed resistance. Also aluminum is dangerous because you can electrify it if its floating by 1 megaohm, I would not do that.. maybe this is the main reason why? I would put a few parallel movs that trigger at like 60V and possibly a ground short trip circuit on it if significant current is detected through the movs to render the work surface safe if it gets electrified to HV. Working electronics on aluminum kinda feels like working electronics in a puddle to me.I guess its pretty safe though, you would have to touch your leg on a radiator or something and have a ground referenced HV potential in the circuit, it might suck if you are leaning on it and touch a test equipment on a work bench above the mat though if its electrified. And if you put equipment on it you short out the 1meg saftey resistor, with a low conductivity mat you still have the mat resistance helping you.. As soon as you short out that resistor you will rapidly discharge parts so you can get a current spike that damages something charged?My mat is very resistant, it does not react to a soldering iron, the reason it has burn marks is from having a temperature calibrator on it that got to like 500C for a long period of time, I did not realize I forgot my ceramic standoff.

author: nanofrog
author_rank: Super Contributor
timestamp: August 21, 2018, 02:08:04 am
content: Rubber ESD mats are made of nitrile rubber, not silicone. Bottom layer is carbon filled.The commercial product I'm aware of isTechspray's Zero Charge Mat & Table Cleaner. The closest distributor isTesterionin South Africa (looks like you'd have to make email or phone contact).

author: rdl
author_rank: Super Contributor
timestamp: August 21, 2018, 03:13:03 am
content: I'm surprised no one has created some kind of "rejuvenator" coating for these mats. Lots of people use them and they almost always end up looking bad.

author: coppercone2
author_rank: Super Contributor
timestamp: August 21, 2018, 12:45:22 pm
content: I gave it a try sanding it. I tried160 grit at first, using a random orbital sander (ridgid model), wet, it did not do too muhc120 grit second try, wet, using random orbital sander. I had to remove quite a bit of material , to where the mat is smoother but has not lost all its texture. Certain parts got sanded smooth, to the new blue color, whereas most of the mat just lightened up ( I wanted to retain at least some of the grooves for slip control).It looks alot better. It was smooth enough after 120 grit that I did not bother polishing it anymore. Testing to follow.Looks alot nicer, kind of like a blue gassy nebula with a black hole (burn mark) in the middle. I am very satisfied any the lab should be dim anyway to protect the CRTs being run at lowest brightnesI will give the finished job a 7/10 now, I don't mind the brighter splotches or the burn mark too much.If you don't care about surface texture/grip, you can keep sanding it down till its fully restored to I guess a 9/10, maybe 10/10 if you are good with a sander.