[scytheavatar]

a) When there's no issue of the heat sink fitting the case is taller = better? As in more heat will be removed?

b) Is thermal component/thermalsil necessary or recommended, again if there's no issue of the heat sink touching the case?

 

[error401]

Quote:

Originally Posted by scytheavatar /img/forum/go_quote.gif a) When there's no issue of the heat sink fitting the case is taller = better? As in more heat will be removed?

Yes, with diminishing returns.

Quote:

b) Is thermal component/thermalsil necessary or recommended, again if there's no issue of the heat sink touching the case?

Yes again, the thermal paste or pad is compliant, while both the IC case or heatsink are not. The thermal material fills in the microscopic gaps between the two, greatly increasing the contact surface area. At a microscopic level both surfaces are quite rough, and will result in surprisingly poor heat transfer (a result of a small contact surface area) without a good thermal conductor to fill the gaps.

If you don't need to electrically isolate the heatsink though you can safely just use thermal compound without thermalsil/mica/kapton and increase the transfer efficiency a bit. It's still probably a good idea to at least consider isolating them anyway just to reduce the chance for a mishap frying your amp.

 

[TimmyMac]

Quote:

Originally Posted by error401 /img/forum/go_quote.gif It's still probably a good idea to at least consider isolating them anyway just to reduce the chance for a mishap frying you or your amp.

This. The heatsink tab on most TO-220s is internally connected somehow, so it's usually a good idea to isolate it.