SOT223 cooling?

[Wavebourn]

What the lowest thermal resistance may be obtained if I bolt SOT-223 device on a copper plate?

They are usually rated for 83K/W, is it in case of soldering to a copper clad board?

[Wavebourn]

Here is an answer from Fairchild:

http://www.fairchildsemi.com/an/AN/AN-1028.pdf

[jcx]

if you want to stick with conventional smt assembly you can buy smt heat sinks that get the heat off the board much more effectively than just using Cu plane area
http://www.aavidthermalloy.com/cgi-b...ce=14&x=31&y=6

designed for bigger smt pkgs but no reason you couldn't butt a sot223 tab against one of the legs of these heatsinks, probably good for 2-3W

there is still some limit due to j-c thermal resistance that inclues a die size term

http://www.diodes.com/zetex/_pdfs/3.0/pdf/SOT223.pdf

looks like >5-6W would be possible with a chill plate

[Wavebourn]

Thanks JCX, I need 2.5W, and I am free to bolt or solder it to anything I want, so it is not a problem. Cool! BSP225 from Philips rulez!

[MaxS]

Hello



You already have find great stuff.
But in a case of SMT oven production, you have to know that cooler make soldering harder due to cooling thermal power (destined to solder) from transistor to PCB (I don't know if this phenomena is reproducible on plate) but I want to warn people about that before they go crazy.



MaxS