# Thread: Traces on PSU boards

1. 1kW User
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## Traces on PSU boards

Could someone help answer this for me;

I think I'm right that a single piece of wire say 1mm thick can take less amps than say a piece of wire with 50 strands but still 1mm thick.

So how is it possible for a PCB trace in a PSU to take the massive AMPs in todays latest PSU's?

2. The traces usually don't need to go far, and when they do thicker traces are often used.

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Originally Posted by Oklahoma Wolf
The traces usually don't need to go far, and when they do thicker traces are often used.
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4. Flux Capacitor User
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I don't know much about mobo design itself, but wire thickness is proportional to amp carrying capacity, ie thicker wire will carry more and heat up less. There are at least 2 simple equations, one is ohms law. I can give you the other if you are interested.

It defines the resistance of a piece of wire...

It Resistance, R = ro ( a greek letter, to do with the type of metal, say copper or silver ) times length divided by area.

Incidentally, capacitance has a similar equation, so does inductance.

Capacitance = epsilon nought(another greek letter to do with the dielectric..insulator between the metal plates) times Area of plates, divided by distance plates are apart.

( a cap is just 2 pieces of metal with an insulator in the middle, akin a sandwich, usually rolled up into a swiss roll shape.

so for wire resistance, shorter length or fatter area means less resistance, means less power dissipated into heat, which may in extremes fuse the metal.

power lost( heat) = (current squared) times resistance ( which is why power cables use low current(high volts) and thick wires)

For voltage its all about insulation thickness.

Its poss. that the monster ampages the rails sort of split or divide up, so the capacity is shared??
Last edited by ianm2; 01-07-2007 at 03:03 PM.

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