PTFE or other electrical insulation coating for Stainless Steel

[KENAT]

I'm looking for an electrical insulating coating for a very small stainless steel clamp used for holding samples on a type of microscope.

Max current is 1 micro-amp. Maximum voltage 12V. So not too demanding.

Only some surfaces are coated, and volume will be very low.

I was thinking of using PTFE, but was having trouble finding any reference of how to call it out on drawings. Any help in this department appreciated.

Or, if someone has an idea for an alternative I'm open to suggestions.

Thanks,

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[Compositepro]

How about applying ptfe tape that has a pressure sensitive adhesive. (or Kapton)

 

[KENAT]

The geometry is maybe a bit fiddly for tape. It's similar to a very small hook clamp and I need to insulate the area around the spring, including top & bottom. Thanks though.

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[IRstuff]

How about the stuff used to coat tool handles? I know that you can buy something like that in spray form from Home Depot and the like.

TTFN

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[Compositepro]

Well how about a varnish like that used for insulating magnet wire? Why ptfe?

 

[KENAT]

PTFE was my first thought because I'd seen it used in this type of situation, but I wasn't convinced it was the best option hence the second part of my OP. Also, the low friction is beneficial though not critical.

I'm really space limited and I need the coating to be really thin - a few thousandths of an inch at most. I saw some info on PTFE coating being only .001-.003" thick which is about right.

Thanks IRstuff, nothing turned up when I was searching yesterday but using words from your post I was able to find some 3M Scotch Insulating spray and some 'liquid electrical tape'. The 3M data sheet doesn't really give enough info to decide for sure, and the liquid tape looks like being too thick and probably too high friction, but they're in the ball park.

I'd forgotten about varnish, thanks compositepro.

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[swall]

If you are going to look at varnish, you could also look at epoxy powder coat. Thicknesses of .001" to .003" are readily attainable.

 

[btrueblood]

Kenat,

Look up Xylan coatings, made by Whitford Chemical or something like that. They have a variety of formulations including teflon-like derivatives, and either powder or wet application methods, typically followed by a controlled medium-temperature (400F or so) bake. We've used it to create low-friction, and/or low-wetting surfaces and insulating surfaces on 303 machined parts, with about 63 rms or so finishes. If you contact the mfgr., they can probably help you find a vendor to do the coating for you, if you don't have resources to do the coating yourself.

 

[KENAT]

Thanks btrue, we don't do any machining etc. so we'd be outsourcing both the machining and coating of the part.

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[unclesyd]

I would take a look at the Glyptal line of insulation conformal coatings.
I've used several different products, all with excellant results.

http://www.glyptal.com/Glyptal_Product_Data_Sheets.htm

 

[MagMike]

I would suggest Parylene. Electrically resistive, coefficient of friction close to Teflon, and you can mask the sections you don't want coated. Usually the coating thickness is .0003" to .0005", but I've had some parts coated up to .002".

There are a number of good vendors out there, you'll probably find the lot charge to be reasonable.