Silicon around plasma buffer ICs.

[Dang]

Just want to know what it is and where can it be found? thanks, Andy.

[Dang]

Re: Silicon around plasma buffer ICs.

Any ideas please? they would be very helpful, thanks.

[budm]

Re: Silicon around plasma buffer ICs.

Are you talking about Silicon thermal interface or Silicon thermal compound?
For example:
http://www.bergquistcompany.com/thermal_materials/
Digikey sells them.

[tom66]

Re: Silicon around plasma buffer ICs.

Insulator stuff. Never used it myself. But would imagine some kind of silicone RTV could work OK.

[Dang]

Re: Silicon around plasma buffer ICs.

Yes, sorry, tried to be as clear as I could, it is the insulator stuff that I need, that RTV silicon looks OK, I'll give it bash, thanks peeps.

[drussell]

Re: Silicon around plasma buffer ICs.

Do NOT use regular automotive-type RTV silicone! It can easily become slightly conductive and completely defeats the purpose of putting it there, plus some of them are corrosive. The sensor-safe ones shouldn't be corrosive but still are still a terrible choice for insulating any significant voltage.

Electronics stores sell a whole range of special RTV silicone which is similar but has defined electrical insulating characteristics (quite good ones at that!). The antique TV guys use it to recoat flyback transformers, etc.

It is available in caulking-tube sizes but is quite expensive and luckily smaller tubes of it are available in several sizes for a reasonable price for the amount used in typical litle projects. There are several series of electronic ones like RTV162, RTV103 and RTV133 high voltage available with different colors and various properties, any of which should be fine for buffer ICs, just don't use automotive RTV if you want a reliable repair.

There is also good old' MG Chemicals "Corona Dope" which is a great insulator (used to be used by TV techs all the time on flybacks, etc.) and should work fine for insulating buffer ICs.

Bob Andersen has an interesting video where he talks about the silicone he uses on flybacks. I'll see if I can figure out which one it is and post a link here.

I buy mine at a local electronics supplier but you can search somwhere like Digikey for "RTV" and you'll find some of them.

[budm]

Re: Silicon around plasma buffer ICs.

You need electronics grade RTV, regular RTV is corrosive as mention above.
http://www.amazon.com/Clear-Electron.../dp/B0063U2RT8
http://www.hmcelectronics.com/produc...licones/RTV162

[rievax_60]

Re: Silicon around plasma buffer ICs.

I used this product, http://www.permatex.com/products-2/p...-sealer-detail
It bugs me when the plastic cap cracks up a short time after the tube is first opened. I have been bitching to Permatex about this on their Facebook page.

[Dang]

Re: Silicon around plasma buffer ICs.

Thanks once again peeps, as always highly informative with good advice, Andy.

[drussell]

Re: Silicon around plasma buffer ICs.

I can't seem to find the one where Bob receives his order with the RTV133 (very high voltage stuff, unnecessary for buffer chips but interesting, none the less) where I think he mentions how much the big tube cost, but the one where he first opens it to do his first flyback re-coat:

https://www.youtube.com/watch?v=BhK19ZU7LSE

Another one where he talks about re-coating a Predicta flyback in more detail:

https://www.youtube.com/watch?v=ni97Sz2oupw

He mentions it at about 16:00 and then actually re-coats the flyback at about 31:00

I've watched every one of his videos all the way through. I find them very interesting and informative. Much more interesting than most of the crap that is on regular TV.

Always makes me want to find a cool old TV and do a really good, thorough restoration.

I recently almost managed to snag a 1972 Electrohome all-tube color TV similar to the model we had when I was a kid (same 25" chassis, different cabinet) but the original owner who had already promised three of his four giveaway TVs to another person didn't realize it was one of the ones they wanted. DRATS! Been looking for one of those for many years, have to keep looking....

[drussell]

Re: Silicon around plasma buffer ICs.

I used this product, <link to Permatex Windshield & Glass Sealer>

Even though it worked for rievax_60, and I hope it holds up for him in the long term, I wouldn't use that for this purpose since it has not been formulated with any attention to corrosiveness or electrical insulation. Even though they are designed for "sealing", many of the silicone formulations stay slightly porous and can actually wick up moisture. Not something you want with a few hundred volts and very close spacing.

That stuff IS great for re-attaching vacuum tube and CRT bases when they come loose as it has a bit of flexability so it won't end up cracking the glass on repeated temperature cycles like something very hard such as epoxy might do.

[budm]

Re: Silicon around plasma buffer ICs.

RTV133 spec:
http://www.momentive.com/products/sh....aspx?id=10299
Very expensive @newark:
http://www.amazon.com/Momentive-RTV-.../dp/B00746MJRA

http://www.newark.com/momentive-perf...1430955|plid||[keyword_text]|match|p&CMP=KNC-GUSA-GEN-SKU-MDC-MOMENTIVE_PERFORMANCE_MATERIALS

[drussell]

Re: Silicon around plasma buffer ICs.

Ahh, interesting, I'd never bothered to actually pull a datasheet.

Bob states the dielectric specification incorrectly in his video. He says it is 20kv per mil (which I always thought sounded optimistic), it is 20kv/mm or 500v/mil. Still impressive but that makes far more sense!

[freakaftr8]

Re: Silicon around plasma buffer ICs.

A philco predicta flyback runs about 24,000 volt I believe. But that's amazing I just been using grey RTV silicon from Permatex for a long time now it says it's sensor safe and I haven't seem to have a problem as of yet and I have prepared a lot of 42 inch Samsung buffer boards.