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What will 30A do to cheap stripboard? Answered

I'm building a motor driver, and wanted to build it on stripbaoard, but I'm guessing that it is not designed to take the power I'm using, which will be about 30A continuous at around 25V, although I may be using it for up to 90A continuous at a lower voltage.

The circuit will be fully heatsinked, with an 80mm cooling fan, but I expect the tracks will still get very hot, seeing as the recommended area for wire at 30A is about 6square millimeters.

How long will it take before something breaks or burns up?

How much do the tracks need to be built up to handle the current without getting excessively hot?

Thanks in advance.



Best Answer 8 years ago

By stripboard, do you mean a breadboard type where the components are soldered in place, or do you mean a solderless breadboard where you plug jumper wires in?

If it is the type you solder to, then you would need to know the copper thickness that the board is plated to. PCB material is usually specified in "ounces", so a board plated with 1 oz. copper would have one ounce of copper per square foot, which translates to about 0.001 in thick. I doubt that any general purpose breadboard product would be plated any thicker than 1oz, and it is most likely 0.5 oz. At any rate, I don't thknk it would be wise to expect the traces on such a board to handle 30A.

If you have a small piece of board you are willing to sacrifice, you could set up an experiment where you pass the desired current through some traces and see what happends. I don't know how wide the strips are, but if they are the size of the breadboards I've used, I don't think they will last long at 30A.

One solution would be to route actual copper wires along the tracks where hight current is needed, usuing a suitable size wire. Also, useing the cooling fan to cool any high current areas of the board may help (but it won't let you put 30A through thin traces.

The SkinnerzLargeMouthBass

Answer 8 years ago

Thanks for the reply.

I am using normal 0.1" stripboard, that the components are soldered to.

I guess standard board shouldn't be trusted with anything in excess of 1A, so having to build up the tracks with additional wire was expected. I was wondering how much additional conductor needs to be added to handle the current.

I have some scrap board from a failed project, so I'll dig out the temperature probe and put some current through it.


8 years ago

90 Amps will do A HELL of a lot and I mean the  Biblical Hell  to your Stripboard,
it may actually strip it ( remove the copper in a single Hellish event ).
Unless you know the  Heavenly Secret.
Just solder a bare 14 gauge wire on top of the copper trace !.....     A     

The Skinnerziceng

Answer 8 years ago

At the moment, building the tracks up with some more copper, and see how it goes.

I'll remember that first bit when I need to remove some tracks.

Thanks for the advice, helpful as always.


8 years ago

30A will probably cause the tracks to melt. I used 100A @12v and the tracks peeled off and melted. I had to re make it using fairly thick copper wire instead.


8 years ago

The rules for conductor area don't work for PCB traces, the cooling effect of the thin track has to be taken into account very much.

The Skinnerzsteveastrouk

Answer 8 years ago

Thanks for the tip, I'll see if cooling reduced the amount the tracks need to be built up.


8 years ago

No a breadboard is not suitable.

@30A you'd be far better served by applying only your digital/analog control circuitry on the board, then taking whatever heavy duty components are required to a separate assembly, ideally in a steel enclosure.. The control and feedback signals can be routed to from the heady duty components via 22-24ga stranded wire. That is, your transistors/FETs, IGBTs/whatever get mounted to heatsinks and wired point to point, along with circuit breakers, relays, and so forth.

Wiring for your actual motor drive circuit should be sized not only for the continuous duty current , but also to accomodate startup transient load current. Assume roughly a 1.35-2 times the continuous to account for startup when you size your load wiring and you should be fine. (the more you lean to the larger number, the lower the resultant heating and power loss in your lines will be)

For a PCB, you'll want to use at least 2oz copper tracks, (if exposed, ie, top or bottom layer), about 1.5 inches wide, assuming 1.5x the cont. load current, which is why I think you're better off using point-to-point wire connections for the heady duty components. If you'e dead set on PCB, I'd consider having the power lines overplated to 4oz.