zuq
Member level 3
Hi
I am trying to calculate how much copper area I would need to cool a surface mounted power MOSFET as heat sinks can't be used.
I got this formula from wikipedia but I get awkward numbers,
I know what my Rsa (sink to ambient) thermal resistance needs to be.
Thermal resistance = kA/T ---------k is thermal constant for copper i.e. 401 W/mC (Watts per meter degree Centigrade)
I am assuming a standard copper track is about 3mils thick i.e. (76.2micro meter)
I want Rsa of 1.5 C/W
Using the above equation to find Area I get a huge area...
What am I doing wrong!!
Most likely to be using 4-6 layered board with plated through hole vias for cooling....
Thanks
I am trying to calculate how much copper area I would need to cool a surface mounted power MOSFET as heat sinks can't be used.
I got this formula from wikipedia but I get awkward numbers,
I know what my Rsa (sink to ambient) thermal resistance needs to be.
Thermal resistance = kA/T ---------k is thermal constant for copper i.e. 401 W/mC (Watts per meter degree Centigrade)
I am assuming a standard copper track is about 3mils thick i.e. (76.2micro meter)
I want Rsa of 1.5 C/W
Using the above equation to find Area I get a huge area...
What am I doing wrong!!
Most likely to be using 4-6 layered board with plated through hole vias for cooling....
Thanks