PCB Traces- Current Capacity?
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I wanna build a BS2 controlled speed control for 3 RC motors on one
board- much cheaper and funner than buying 3 separate units.
It'll use 3 MOSFET H bridges, passing about 20a/12v each...
Question: How do you determine appropriate trace width on PCBs for high
currents?
patmat
board- much cheaper and funner than buying 3 separate units.
It'll use 3 MOSFET H bridges, passing about 20a/12v each...
Question: How do you determine appropriate trace width on PCBs for high
currents?
patmat
Comments
writes:
> I wanna build a BS2 controlled speed control for 3 RC motors on one
> board- much cheaper and funner than buying 3 separate units.
> It'll use 3 MOSFET H bridges, passing about 20a/12v each...
> Question: How do you determine appropriate trace width on PCBs for high
> currents?
Check www.expresspcb.com -- they have a chart showing trace-width versus
current.
control, rated for many tens of amps, I see several paralleled MOSFETS, and the
power traces aren't particularly wide... .150-.200" between 'FETs, widening out
to maybe .300" where the 12 guage wire is soldered on... but there is a thick
layer of solder on the traces...
patmat
Or here's a thought: I can't see the top side, cause the 'FETs are jammed
together and there's a big gob of glue, but maybe the traces are replicated on
the top side, doubling the copper...
> patmat
> Question: How do you determine appropriate trace width on PCBs for high
> currents?
12V and 20A? Use wire. Copper for that size will have to be very thick and very
wide. 1/2" trace widths wouldn't be out of line. Your other option is to make
the traces about 1/4" wide and solder a piece of 14awg house wire (solid of
course) to it as added current carrying area. I've seen this one used in very
high powered switching power supplies for the DC output rails, as well s sing it
in a few of my own designs. Make sure your PCB is heavy duty, as soldering the
wire to the trace will take a fair ammount of heat. Don't try this with anything
smaller than a 200W gun either. I used the 500W iron at work. Not exactly the
prettiest way to go, but it's a lot cheaper than the alternatives.
-dave
Discretion is the better part of valor
dave paton http://homepage.mac.com/dpaton dave at ieee dot org