Mica in Heatsink TO3 power transistor or no ?

[aldovan]

Friends

I want know if the heat transfer is best with mica isolator or without it.
I do not need mica for electric isolation.
I will use in a TO3 package power transistor.

Thanks in advance,

Aldovan

PS: I will use termic paste.

[sawreyrw]

The lowest thermal resistance will be without the mica washer, so if you don't need electrical isolation, don't use it.

[djk]

Mica and grease is about 0.3*C/W, grease only is about 0.1*C/W