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crgwbr
07-23-2006, 07:50 AM
Hey Everyone,

I'm Building a motor controller for a rather large BS2 controlled bot (50+ Pounds).· I can handle designing the boards, thats no problem; what has me stumped, is how to put high current through a PC Board.· The most I've ever put through one is 5 A.· I've though of jumper soldered over the traces, would this work?· Any other suggjestions?

Thanks

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PJ Allen
07-23-2006, 08:14 AM
· The copper-cladding comes in more than one thickness.· A good thing to do is make·high-current traces wide and thick.· Input and output wires should be on solder lugs which get·connected to the board·on big "pads" with a screw, washer and nut.

· You want the contact to be metal-to-metal, a true physical connection,·and not basically·through solder.· You only want solder to re-inforce/aid the connection, not to make it.

Bruce Bates
07-23-2006, 10:37 AM
crgwbr -

I am by NO means a draftsman or artist, but the attached rudimentary drawing ought to give you the idea of what PJ was saying, in relative terms. The BROWN areas are PURE COPPER and the SILVER/GRAY areas are solder-on-copper. The machine screws indicated could just as well be a nut-bolt-washer set-up as PJ suggested.

Regards,

Bruce Bates

pjv
07-24-2006, 12:28 AM
Hi crgwbr;

It all depends on how much voltage drop you are able to tolerate. Generally if I have more than a couple of amps flowing on a steady basis (pulses may be more tolerant) then I "beef up" the copper trace by forming and soldering overtop of it a sturdy piece of buss wire, 18 or in some heavy current cases even 16 ga. The joint is also completely filleted with solder, giving the effect of an even heavier wire.

Where needed, it works great.

Cheers,

Peter (pjv)

bennettdan
07-24-2006, 05:24 AM
How much Current are you looking at using? Here is a websight that has a few PCB calculators and has one for current through traces which will tell you how thick and wide the traces need to be.
http://www.saturnpcb.com/Software.htm#3

Post Edited (bennettdan) : 7/23/2006 10:32:38 PM GMT

crgwbr
07-24-2006, 07:52 AM
...·I "beef up" the copper trace by forming and soldering overtop of it a sturdy piece of buss wire, 18 or in some heavy current cases even 16 ga. The joint is also completely filleted with solder, giving the effect of an even heavier wire.
Thanks, I'll Do this.· I'll be conducting 25-30 Amp, so I'm going to do this using 0.080 inch trace, with·14 or 16·gauge copper wire soldered over it; and and an·"airconditioning/cooling" system.

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Alan Bradford
07-24-2006, 08:14 AM
Hi,

I have a power supply board I use for powering industrial motion control Servo Motors.
It is 15 amps at 80 volts DC. I usually use Express PCB for my boards. but they only have 1 Oz. copper.

For this board, I use Pad2Pad (www.pad2pad.com (http://www.pad2pad.com)).
It is a little more expensive than Express PCB, but it fits my needs.

They have 2 Oz. copper boards. I use .150 traces bottom and top for the power traces. This board handles the surges up to 50 amps for a second. There is lots of capacitors in my design.

·If you give a 2 week lead time the boards are not too expensive, and look much better than soldering wires onto traces.

Alan Bradford
Plasma Technologies
www.plasmatechnologies.com (http://www.plasmatechnologies.com)

crgwbr
07-24-2006, 06:51 PM
Thanks, but I was planning on etching my own boards, so I'll stick·with the buss-bar
·fo now.

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bennettdan
07-25-2006, 08:59 AM
Crgwbr
Why dont you find a mosfet with a Isotop so you can have screw connections to your motor? They are not to costly if you look ..you can buy them for about 20 from digikey..

crgwbr
07-25-2006, 07:06 PM
$20 Each! That means it would cost me $320, just for the mosfets. For that price, I might as well buy a sidewinder (http://www.robotpower.com/products/sidewinder_info.html)

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bennettdan
07-25-2006, 10:19 PM
I didnt know you needed so many motors to run..one more thing you can try is what I did was take a peice of flat copper bar .250 wide .080 thick and drilled holes and solder the mosfet pins into the holes and then use isolated standoffs to mount the buss bars...

crgwbr
07-25-2006, 10:21 PM
Thanks, for the idea.

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