# trace width for 2A current

Discussion in 'Electronic Design' started by Ajab, Dec 7, 2007.

1. ### AjabGuest

What is the ideal trace width for 2A current...on a Non Impedance
controlled board?
I tried calculating it ..but the values are different...
Can anyone tell me regarding this?

2. ### Guest

How thick is the copper? How thick is the board? How much temperature
rise? How long?

3. ### AjabGuest

The Cu is 0.0675 on top and 0.0350 on internal layers. Temp rise is
not mentioned. but the system will operate in industrial area. 2A
current is the max current. It is not constant.1.6-1.7A is the
constant current. But sometimes 2A. board thickness is just 3.2782 .

5. ### EcnerwalGuest

There is no "Ideal". There is "good enough", or preferably, "Good enough
plus some margin for error." More is approximately always better, since

How much room have you got? How wide can you make it?

If you can cram in a 3/8" (centimeter) wide trace, do so. If you have to
narrow the ends down to make things fit, do that. If your PCB program
can't manage that, use one that can. If you are tightly space
constrained, the question becomes more along the lines of "what's the
bare minimum I can get away with?" Then you can work up from that if you
can make the space. Here a a couple of guesstimators for that:

http://www.circuitboards.com/capacity.php3

http://circuitcalculator.com/wordpress/2006/01/31/pcb-trace-width-calcula
tor/

6. ### John LarkinGuest

A skinny trace, 20 mils (0.02 inches) wide maybe, can handle 2 amps.
But you should calculate the voltage drop and see if it's going to be
a problem.

1 oz copper has a resistance of about 500 micro-ohms per square, and
the number of squares is just the trace length/width ratio.

But you're lucky to get 1 oz copper even when you specify it, so
overkill some.

John

7. ### John LarkinGuest

Cool. The trace width should be NaN.

John