Thermal pad instead of mica/grease?

[tyttuut]

I'm working on my Yamaha CA-610 II, and I decided to replace the thermal paste on the power transistors. This seemed to work fine at first, but it turned out I had applied way too much and it got into the transistor sockets. I'm looking for an alternative, because I'm pretty tired of getting thermal grease everywhere!

I know there's silicone thermal pads for this kind of application, but I don't know what kind of pad to look for, and I'm also not sure if it'll be conductive enough compared to mica and thermal paste.

 

[petehall347]

use less grease .you only need enough to fill imperfections .

 

[tyttuut]

use less grease .you only need enough to fill imperfections .

Is there any particular place on the transistor where it should go? (They're TO-3 transistors)

I also find the mica pads to be particularly irritating, but I guess I'll make do if I have to.

 

[petehall347]

if you really want to use thermal pads there are different ones . some are better heat conductors than others .

 

[tyttuut]

if you really want to use thermal pads there are different ones . some are better heat conductors than others .

Can you suggest something that would work?

 

[petehall347]

sorry i never use them ..best wait for someone else that uses them and knows the best ones to use .

 

[tyttuut]

sorry i never use them ..best wait for someone else that uses them and knows the best ones to use .

Alrighty, I'm just going with thermal grease and mica insulators until I can find a suitable pad.

 

[petehall347]

spread it very thinly . so long as see a tiny bit ooze out around the edges it is enough .

 

[invaderzim]

Keratherm Red Pads come highly recommended on another site. They aren't cheap though. I've only used them once so far but it was nicer than messing with the paste. Search for "keratherm transistor insulators"

 

[avionic]

You just need a real thin film of transistor thermal compound on both sides of the mica insulator.

 

[triode17]

Except for special metal loaded, ceramic military insulators, you can't beat mica and grease. Yes its a mess but it works better than pads. What I do is trowel just a bit of grease across the mica using a single edge razor blade. It should only be about 1/1000th of an inch thick. Too much, and it starts to act as an insulator. It doesn't need to goo out the sides.

 

[BinaryMike]

Silicon thermal pads are available in a wide range of performance levels, including some with markedly better thermal conductivity than mica and grease --- similar to grease alone. The vendors have published a number of papers on this topic over the years. Check their websites for relevant literature.

 

[ConradH]

The best pads are pretty good, but also pretty expensive. Look up the A2000 material.

 

[Rational35]

This test of thermal pad materials by NASA has some informative results:
https://tfaws.nasa.gov/TFAWS03/Data/Thermal%20Session/Glasgow.pdf

The highest-performing material they tested is available from Mouser, but only in 8"x8" or 16"x16" sheets, for just under a dollar per square inch. fwiw.

Peter