Calculating thermal resistance of aluminum

Thread Starter


Joined Feb 14, 2011
I have the dimensions for an aluminum heatsink I'm using and I would like to calculate the thermal resistance of it. What formula would I use for this?


Joined Feb 11, 2008
I screw a transistor to them, the transistor has a pot on the base. Then adjust the pot and/or variable PSU until the transistor is dissipating 1W or 10W etc, then measure the temp on the heatsink in varying conditions, ie horiz, vert, with something pressed up against it etc.

Sometimes empirical measurment is the best, it doesn't take long and can give you real world info that calcs can't always deliver.

Then when you are done it's only one screw and the transistor and pot comes off and you put it in your junkbox ready for next time. :)