Project boards. Track current?

[eclectic]

I've seen recent posts concerning project boards controlling
relatively high-power outputs.

A genuine question:- what is the current capacity of the tracks?

As an example, the 20M board. (AXE118)
The ULN2803 can easily handle >100mA per output. All outputs on.
http://www.rev-ed.co.uk/docs/ULN2803A.pdf
Page 5. fig 12

The photo shows the back of my 20M board.
At present, I'm connecting V+ (5V) to the top left (Large V), but testing only
low power LED's.

When I move to the 300mA monster LED's, I'll remove link1 and use the line
of individual connectors. (little v).
Only one or two LED's will be switched at any one time, as per datasheet.
But, can the ground tracks cope?

Or should I make alternative arrangements?

e.

 

[Dippy]

A standard 1oz /sq.ft copper pcb 1mm track can easily handle an amp. With a 10-15oC rise in temp it can handle a couple of amps.

There are on-line calculators.

I use the one provided with Easy PC CAD which is blooooming useful and does all sorts of things. You probably don't get these sorts of extras with freebies.

 

[eclectic]

Cheers Dippy.

I had already looked at the table in Express,

0.010" 0.3 Amps
0.015" 0.4 Amps
0.020" 0.7 Amps
0.025" 1.0 Amps
0.050" 2.0 Amps
0.100" 4.0 Amps
0.150" 6.0 Amps

but being of a nervous disposition, I like to double-check.

e

 

[westaust55]

Scaling off your photo, based on IC pin cetres of 2.54mm or 0.1 inch, seems like the trace width is 0.64mm or 0.025 inch.
Presuming a 1oz weight copper plating for the PCB

Then from a nomogram I have, 1 amp at 10 deg C rise and 2 Amps at 30 deg C rise.

 

[Ralpht]

Eclectic,

I used to design boards for work and still do for my own projects.
The figures and graphs shown above are spot on and what I use as well, plus some others.

Your board looks OK and will handle what you will be asking it to do. If you really want to use the "belt and braces" method to be sure, then run jumpers on the board paralleling the PC board traces. These will take the load off the traces themselves and give you peace of mind.

May not look too flash, but if it takes the uncertainty away then it's OK.

I personally won't bother as I'm sure the traces will take the load.

Ralph

 

[Andrew Cowan]

If you make your own boards where exposed copper is visible over the whole track, stick some solder over the track. As RalphTeichel said, it may not look too flash, but if it takes the uncertainty away.

Andrew

 

[eclectic]

"it may not look too flash" I agree totally Andrew.

I've done that before, but now, I can't achieve the
correct level of catatonia to solder 'em!

e