The dissipation due to trace losses should be very small compared to the loss in the FET itself. What package are you using for the FET, and how is it connected in the circuit? Hopefully its one where the tab is connected to circuit ground...Thanks mtwieg,
Great article, However I am a bit confused, how do I account for the fact that the PCB tracks will be getting hot due to current flowing through them and other components relying on tracks for cooling?? how do I put the whole image together?? any ideas??
Definitely; at least on the track/planes connected to the thermal tab on the package.I guess, if I can meet my cooling right, width should of track should more or less be adequate to carry the current??
Yeah, just go crazy with the vias. If you're really serious about this (it's for a production design) you should speak with your PCB manufacturer. They may offer things like filled vias which greatly improve their thermal conductivity. Also their are aluminum backed PCBs which are made specifically for this sort of thing (though I don't have much experience with those). Also having heavier copper thickness helps a lot too.Thinking of using 4 layered PCB, 2 internal layers and mounting a heat sink on the back of PCB, would that do much help or vias limit the use of heat sink?? from that article you mentioned vias seem to have quite high thermal resistance...more vias to solve the problem?? (parallel)
I am not building a commercial product.
How did you attach heat sinks to Power Mosfet bus bars?? did you have three heat sinks, one on each bar?? cant use one big one otherwise you will short the DC bus??
How did you work out how big your copper bars had to be to carry current and for cooling etc?
By the way the first picture in your post did not show up, could you please attach that again, I only see three pictures. Thanks
I guess, if I can meet my cooling right, width should of track should more or less be adequate to carry the current??
Thinking of using 4 layered PCB, 2 internal layers and mounting a heat sink on the back of PCB, would that do much help or vias limit the use of heat sink?? from that article you mentioned vias seem to have quite high thermal resistance...more vias to solve the problem?? (parallel)
Yeah, just go crazy with the vias. If you're really serious about this (it's for a production design) you should speak with your PCB manufacturer. They may offer things like filled vias which greatly improve their thermal conductivity. Also their are aluminum backed PCBs which are made specifically for this sort of thing (though I don't have much experience with those). Also having heavier copper thickness helps a lot too.
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