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Old 27th October 2009, 05:19 PM   #1
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Default PCB track width?

Hi!

I'm in the middle of designing a PCB for an audio power amplifier. However I don't know how to estimate how wide the tracks have to be for the more high-current parts, like output, ground connections, power rails etc. Also, I'm not very familiar with calculating the maximum currents that can be expected in these lines.

Any input much appreciated!!

Thanks!
Per

Last edited by per_electric; 27th October 2009 at 05:30 PM.
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Old 27th October 2009, 07:10 PM   #2
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For 10 A you'll need approx. 5 mm traces at 70 um and signal traces 0.5 mm.

PCB Trace Width Calculator
http://circuitcalculator.com/wordpre...dth-calculator

Trace width is very dependent if the trace is at the edge of the board, if the pcb is mounted horizontally or vertical etc.
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Last edited by peranders; 27th October 2009 at 07:14 PM.
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Old 27th October 2009, 07:24 PM   #3
Mooly is offline Mooly  United Kingdom
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Remember also that when it comes to grounds you MUST consider what is actually going to be flowing in the conductors too. You HAVE to design so that all signal grounds are uncontaminated. Increasing the print size 10 fold will not eliminate this kind of issue.

As a classic example of that only today I was looking at an old Rotel amp and the 1 inch or so square copper print that connects the two smoothing caps together has a clearly visible ripple component across it of the order of several millivolts.

You must treat each conductor as a resistance... if it helps put nominal values in of say 1 ohm and ask yourself "would that cause a volt drop that would influence the signal ? " the answer must be NO
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Old 27th October 2009, 07:34 PM   #4
Electrons are yellow and more is better!
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Ground is very critical in good analog pcb's so it can be a good idea to let us review your work, free of charge
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Old 27th October 2009, 07:58 PM   #5
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That would be very kind of you!!

So, as I understand it, the best thing you could do is separate all the signal grounds from all the other grounds, and then run two individual cabels to the star ground?
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Old 27th October 2009, 11:37 PM   #6
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Tinning the track manually, with a good thickness of solder, can up its current rating significantly.
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Old 28th October 2009, 12:12 AM   #7
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Tinning a solid wire continuously to the track helps even more.
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Old 6th November 2009, 12:50 PM   #8
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Tin is by a factor of 10 a worse conductor than copper, any solder ontop of a trace maybe looks good but won't lower resistance much.

Anyway, with 70mum boards currents as high as 15A are not a big deal anyway.

Have fun, Hannes
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Old 6th November 2009, 01:00 PM   #9
wwenze is offline wwenze  Singapore
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Would the tinning result is sonic changes like tinned copper vs untinned copper wires?
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Old 6th November 2009, 01:29 PM   #10
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This is a typical question with two answers:

Yes

No
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