Insulators for Output Transistors

[gaycoh]

Hi all,

Little off topic but related to output stages.
I would like to use aluminum nitride insulators for output transistors
What type of thermal paste is recommend for that insulators?
I aluminum nitride totally better (insulators plus grease) than Keratherm (without grease)?

Thanks,
Guy

 

[xrk971]

I use CPU cooler grease. The really good stuff has fine nano metal particles in it to enhance conductivity. Copper colored paste sometimes. So be careful letting it touch between circuits. It belongs on the thermal pad and spacer only.

 

[gaycoh]

Thanks.
So, can you give a specific example of such a grease?

 

[gaycoh]

For example: Alphacool Eisfrost Extreme ?

 

[Mark Tillotson]

I'd definitely avoid metal-filled paste due to the risk of shorting (and graphite pads too!). ceramic-filled is safe, you can even get diamond-filled. The layer of paste should be as thin as possible, any paste is a much poorer conductor than an AlN pad.