PCB Thermal Copper Area February 16, 2007
I published the following Zoho Sheet to calculate the PCB copper surface area to cool a device based on its power dissipation.
It is embedded below and can also be opened in its own window.
- Posted in : Electrical Engineering, PCB
- Author : Brad
Comments
hi,
can you explain the background behind your Rth sa figure please?
any litterature covering this topic?
Cheers,
Matt
Hi Matt,
See the link below (also at the bottom of the spreadsheet).
“Constructing Your Power Supply - Layout Considerations”, by Robert Kollman
http://focus.ti.com/lit/ml/slup230/slup230.pdf
Brad
hi,
can this calculator be used for high power LEDs as well?
thanks
alvin
Alvin,
The calculation applies to any power dissipating device. However, the default Theta_SA used in the spreadsheet of 1000 (cm^2)*C/W is for convection in still air.
Brad
I like your calculator but I don’t understand the 166 C/W thermal resistance for one sq inch of copper. I see elsewhere it is given as 43 C/W. If you look at any data sheet for a linear regulator in a TO-263 package it is also in that range.
Joel
Joel,
That number came from the referenced paper. I’ll have to look into it. Part of it could be 1 side vs. 2.
Thanks,
Brad