How to apply thermal compound to TO-3 mica insulators

[dlucy]

I've read a few of the threads here on AK on which thermal compound to use and how to apply it when replacing TO-3 transistors. I'm replacing all the output transistors in a vintage Kenwood KR-6140A quadrophonic receiver, so I'm doing this thermal compound on a mica insulator for the first time.

I think I'm doing it right, but will those of you who have done this a million times before please watch and let me know if I'm applying the Aavid Thermalloy Thermalcote I correctly or not?

 

[dlucy]

The end result looks like this:

 

[fred soop]

The end result is excellent. However, you and the amplifier will be dead before you ever get that crap completely off your fingers. If you know of something that cuts through and dissolves it to clean your hands, let us know.

I usually apply using a flat blade screwdriver, first to the transistor. Then set the insulator on the transistor. Then apply to the outside of the insulator. Nothing wrong with your method.

 

[SoundOfSound]

 

[dlucy]

If you know of something that cuts through and dissolves it to clean your hands, let us know.

Uhh... I just sprayed some IPA (91% alcohol, the stronger-than-isopropyl stuff) on my hands and fingers and wiped them down with a clean, rough rag. All the Thermalcote came off fine. That's how several AK'ers describe how to clean up excess thermal compound that squeezes out from underneath the mica, so I figured it would work on my fingers, too, and it did.

 

[ryuuoh]

I put the stuff on my thumb and forefinger then spread it on the insulator. I get good coverage, and almost no squeeze out. Gloves help.

 

[ConradH]

Looks fine. FWIW, I usually put the grease on the TO3 device, then put the insulator on, then grease the other side of that. Gives me more to hold on to and less on my fingers.

 

[Gnesen]

Uhh... I just sprayed some IPA on my hands and fingers and wiped them down with a clean, rough rag. All the Thermalcote came off fine. That's how several AK'ers describe how to clean up excess thermal compound that squeezes out from underneath the mica, so I figured it would work on my fingers, too, and it did.

Would a pilsner work just as well?




Sorry, couldn't resist! Actually, I'm interested in this topic, too, as I'm not positive about the best way to apply thermal paste. Thanks for bringing it up.

 

[dlucy]

I used AAVID Thermalloy's Thermalcote I and the following advice from another thread to get it at a great price...

The price differential between a 1oz. and 2oz tube is less than $0.70. I'd get the 2oz tube. 532-250 if you plan on more than the 1250. Same stuff.

 

[goat67]

Looks good I will put a pea sized glob on my index finger touch my thumb and then just put the mica between my thumb and the index finger and spread it out less is better

 

[Hyperion]

If you know of something that cuts through and dissolves it to clean your hands, let us know.

Spookily WD40 works quite well, however it doesn't go down as nicely as IPA, or a Pilsner.

 

[blhagstrom]

WD40 for old grease clean up.

Has no one heard of Cotten swabs? Q-tips? I have one all good and full of goo that I keep with my jar of grease. A smear on the transister, put the mica on, then a smear on the mica and install.

 

[Retrovert]

The end result is excellent. However, you and the amplifier will be dead before you ever get that crap completely off your fingers. If you know of something that cuts through and dissolves it to clean your hands, let us know.

Fantastik will do it, and it works better than a lot of the lightweight petroleum solvents. I just used it to remove the silver thermal paste from my fingers (and from the CPU and old heatsink) after replacing my CPU watercooler. I looked like I had agyria when I was done.

Most of the white thermal paste is just silicon grease (aka vacuum grease) with aluminum oxide or zinc oxide. So you need something to remove the grease, and the oxides come along for the ride. The el-cheapo stuff, which doesn't work very well, has silicon dioxide in it instead of the Al/Zn.