Semi-OT: Very thin insulation coating

How about Paralyene?

Something as thick as .002" might not be practical, paralyene is usually used as a thin coating more like .0002 but has excellent electrical and biocompatibility properties and deposits (from gas) extremely uniformly. Higher thickness coatings may be available, check with one of the coating service companies.

We are using Parylene elsewhere and our ME said it isn't so suitable for this thicker area. But thanks for the hint about the supplier. We need a coating provider in general because the one we used on the first run has royally screwed up.

Try MWS or some other wire company. They may be able to do the standard magnet wire coating, formvar or polywhatever.

One possible solution: cast the wire in some suitable plastic, then use a lathe to cut away all but the last 0.002". You'll want to keep the wire mandrel under tension...

Not really a solution, but a few wacky ideas:

Sputter/evaporate on some aluminum, and anodize it to make pure oxide.

Flux the wire, and apply sealing-grade glass. Diamond-grind the short length you need to appropriate OD.

Teflon tubing is available down to 32 gage (.007 ID, .006 wall); maybe you can slip some over a length of your wire, and draw through dies to neck it down.

You can buy ready enamelled stainless steel wire just like magnet wire:

That might work.. the 2 mil of coating is hard. My MWS catalog says that their quadruple build of insulation might be enough.

We get wire from California Fine Wire also... which might be better for small volumes... (How many 2" pieces will Joerg get from a 1 lb spool? :^)

George H.

Opposite of X-Var ??

Don't the enamled wire companies face this problem everyday? But do it thinner?

Let's see 4 mils is just a bit smaller than #36 Awg should be a piece of cake.

I have a friend who worked on this kind of coatings for biomedical needle electrodes. I think he used some silicones, but finding the correct combination and process to get good adhesion and correct thickness took some time. I can email you his contact info.

It's a little more complicated than that. For various reasons the coating needs to be applied after the wire is affixed to some other stuff. It also needs to be a supplier with the usual med certs, which can be an issue with wire companies.

Sure, but we need it coated after the fact. Sorry, should have mentioned that. There is a slightly larger structure attached to it which also (later) needs to be coated.

They usually don't have the med certs. But we'll talk to more cable mfgs, hoping to find the rare one who is willing to do a custom coating job and has an FDA-compliant production facility.

Thanks, Mikko, got your email and will fwd this to our ME.

Of course, you need to pay attention to your time budget for this. At one time, I was involved with running an TEM electron microscope. The recipes we used remind me of your requirement. I'd say be wary of signs that say, "Gee Whiz," with a swamp behind them. IOW, seek a solution without a lot of R&D involved.

Have you looked at electrospray type processes? Including powder coating, they put on coatings in your range. You might check with an experienced automobile body shop spray painter, since they coat in this range, frequently and cheaply. ? Just an idea.

John

Ideally we'd like to find a company that is already experienced in doing that sort of coating. But I got hints to some in this thread and we'll explore those.

We tried the paint route, so far no luck.

Ever meet Alex Strojnik? When I was graduate student in Melbourne he'd drop ped in from Croatia for a year to build a 600kV scanning transmission elect ron microscope for the Melbourne University Physics Department. The graduat e students who go to use it after he'd left weren't impressed with it, but graduate students never are ...

His son (with the same name) seems to have ended up in Arizona.

1. The Medical certs are going to kill you cost wise.
2. 0.002 inches? Does it really have to be that thick? GH's post triggered me on this. IF so why?

?-)

opped in from Croatia for a year to build a 600kV scanning transmission ele ctron microscope for the Melbourne University Physics Department. The gradu ate students who go to use it after he'd left weren't impressed with it, bu t graduate students never are ...

We were breaking down the sub-structures of the mitochondria. Also the chloroplast. 3-5 Angstrom level resolution. I don't know the state of the art now - but I have seen 3-D pics in textbooks which would have made Gabor happy.

Usually not, done it many times. One just has to find a shop that has the procedures and certs already in place.

Because some other conductive stuff gets applied onto this and there is a limit to the capacitance. Also mechanical reasons (bending, chafing).