What boards to solder on for high current circuits?

Discussion in 'The Projects Forum' started by x1222, Aug 23, 2012.

  1. x1222

    Thread Starter Member

    Oct 22, 2011
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    I'm working on voltage regulator circuits to control the voltage for 4-5 servos and the total stall torques will be up to around 8 A. From googling, typical PCB prototype boards seem to only be rated for around a few amps. Are there specific boards I should look for to handle the higher currents?
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    No specific boards but the copper trace width and copper oz is taken into account when dealing with high current tracks.

    Another way is to cover the whole trace with solder. This will increase the current handling in thin traces.
     
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  3. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    You might consider using flywires for the high current portions of your circuit.
     
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  4. #12

    Expert

    Nov 30, 2010
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    Found among "notes to myself"...

    for temperature rise = 20 C on a 1 ounce (of copper) per square foot circuit board
    50/1000 of an inch will carry 2.63 amps
    500/1000 of an inch will carry 14.66 amps
    2000/1000 of an inch will carry 48.12 amps

    There are calculators on the internet.

    http://www.desmith.net/NMdS/Electronics/TraceWidth.html
     
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  5. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    "higher" amperage protos are typically done with wires soldered to the traces to increase the current carrying capacity like stated above or done without a PCB at all..(ie point to point wiring to terminal blocks,etc..)
    8 amps on a real fabricated PCB is nothing.. Done ALL the time. I do 100 amps on PCB traces all the time. Usually double sided traces as wide as I can make them with thermal vias to spread the heat.
     
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  6. x1222

    Thread Starter Member

    Oct 22, 2011
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    Thanks guys. I think adding extra solder to the traces will be the easiest way. A 20 AWG wire can hold 11 A, so should I aim to add enough solder on the traces to match the volume of the 20 AWG wires?

    Ya I guess 8 A isn't exactly high current. What are you making that uses 100 amps? Is it for work or hobby?
     
  7. paulktreg

    Distinguished Member

    Jun 2, 2008
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    Better still solder 20 AWG tinned copper wire along the traces?
     
  8. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    Yes. Solder isn't nearly as good a conductor as copper.
     
  9. SgtWookie

    Expert

    Jul 17, 2007
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    Solder has a bit over 5x the resistance of copper.
     
  10. wayneh

    Expert

    Sep 9, 2010
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    That's interesting. It argues for making a solid mechanical connection of two copper wires before applying solder, as opposed to tinning the two ends and just laying them together with solder making the only bond. Stressed to the limit of current, the latter bond ought to overheat and fail like a fuse.
     
  11. x1222

    Thread Starter Member

    Oct 22, 2011
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    Didn't think about the extra resistance of solder, but it doesn't seem like soldering copper wire will be worth the extra effort for my circuit. The resistance for 1000 ft of 20 AWG wire is only 10 ohm. I don't think I will use more than 5 ft worth of soldering trail.
     
  12. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    Here's what I did. The heavy traces are .030" wide and double sided. They are good for 6 amps, but I only run 3-4 amps through them.
     
  13. DickCappels

    Moderator

    Aug 21, 2008
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    Dealing with 20 amps on a PC board, I put down about 6 mm wide traces, then soldered some #12 copper wire along it. The combination is just barely enough to keep the trace from falling off the board. Should work a dream in your case.
     
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