Track width 20A - Electronic Circuits Projects Diagrams Free

leonel · 26th October 2005, 06:41 PM

Hi...
I want to build a pcb, but i have to have one track that has to support a corrent of 20A.
My doubt it's how much width has to be my track to support 20A ?
Regards

Oznog · 26th October 2005, 08:30 PM

It depends on the thickness of the copper.
Also is it an issue of the trace overheating, or the trace's resistance being too high? On overheating you need to consider the thinnest point- likely right at the component pad- as the limiting factor.

stevez · 26th October 2005, 09:09 PM

As a place to start, 12 (AWG) ga wire is often the choice to carry a 20 amp current. It has a cross sectional area of .00513 square inches or 3.31 square millimeters. It would seem that the thinnest cross section of a copper trace would have to be about this cross section or greater. I would think that voltage drop might also be a consideration.

Oznog · 27th October 2005, 01:32 AM

It would not necessarily need the cross section of a 12 ga wire. There are 3 factors here- the resistivity per unit length of the conductor, the thermal dissipation coefficient of the conductor (which is a factor of surface area and insulation thickness), and how hot the insulation can get before failing.

For a PCB trace, the dissipation of a wide trace can be large with relatively little copper, and it is not covered with a great deal of insulation.

Is this a 20 amp continuous load, or intermittent? What are you trying to do?

bloki · 27th October 2005, 06:50 AM

Here you have PCB Trace Calculator:
http://www.geocities.com/CapeCanaver...TraceWidth.htm

Klaus · 28th October 2005, 01:57 AM

Quote:

Originally Posted by bloki

Here you have PCB Trace Calculator:
http://www.geocities.com/CapeCanaver...TraceWidth.htm

I can't see a "calculate" button with this program. Anybody got it to work on a macintosh computer?
Klaus

Russlk · 28th October 2005, 02:41 AM

I found that if I click on the temperature after entering the current, the results show up. Just entering the current does nothing.

leonel · 28th October 2005, 08:52 AM

The current it's intermitent.
Sorry my ignorance, but what is a "12 (AWG) ga wire"? It's a pcb track with 12mm width?

Using the calculator it gives me on the internal result 29mm and in the external result 10mm of about 38.8mm of track lenght.

Russlk · 28th October 2005, 05:17 PM

AWG stands for "American Wire Guage". #12 is .0808 inches in diameter and is rated 14 amps for a 25 foot length. The fusing current (at which it melts) is 235 amps.

bloody-orc · 28th October 2005, 05:40 PM

when the track must carry large currents then a thick coat of tin is added to it. this makes the wire "fat" and therefore you dont need to have a inch wide track. it is made so in PC power suply's etc.

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26th October 2005, 06:41 PM	(permalink)
leonel	Track width 20A Hi... I want to build a pcb, but i have to have one track that has to support a corrent of 20A. My doubt it's how much width has to be my track to support 20A ? Regards

26th October 2005, 08:30 PM	(permalink)
Oznog	It depends on the thickness of the copper. Also is it an issue of the trace overheating, or the trace's resistance being too high? On overheating you need to consider the thinnest point- likely right at the component pad- as the limiting factor. __________________ I thought what I'd do was I'd pretend I was one of those deaf-mutes.

26th October 2005, 09:09 PM	(permalink)
stevez	As a place to start, 12 (AWG) ga wire is often the choice to carry a 20 amp current. It has a cross sectional area of .00513 square inches or 3.31 square millimeters. It would seem that the thinnest cross section of a copper trace would have to be about this cross section or greater. I would think that voltage drop might also be a consideration. __________________ stevez

27th October 2005, 01:32 AM	(permalink)
Oznog	It would not necessarily need the cross section of a 12 ga wire. There are 3 factors here- the resistivity per unit length of the conductor, the thermal dissipation coefficient of the conductor (which is a factor of surface area and insulation thickness), and how hot the insulation can get before failing. For a PCB trace, the dissipation of a wide trace can be large with relatively little copper, and it is not covered with a great deal of insulation. Is this a 20 amp continuous load, or intermittent? What are you trying to do? __________________ I thought what I'd do was I'd pretend I was one of those deaf-mutes.

27th October 2005, 06:50 AM	(permalink)
bloki	Here you have PCB Trace Calculator: http://www.geocities.com/CapeCanaver...TraceWidth.htm

28th October 2005, 02:41 AM	(permalink)
Russlk	I found that if I click on the temperature after entering the current, the results show up. Just entering the current does nothing. __________________ see my website: www.geocities.com/russlk

28th October 2005, 08:52 AM	(permalink)
leonel	The current it's intermitent. Sorry my ignorance, but what is a "12 (AWG) ga wire"? It's a pcb track with 12mm width? Using the calculator it gives me on the internal result 29mm and in the external result 10mm of about 38.8mm of track lenght.

28th October 2005, 05:17 PM	(permalink)
Russlk	AWG stands for "American Wire Guage". #12 is .0808 inches in diameter and is rated 14 amps for a 25 foot length. The fusing current (at which it melts) is 235 amps. __________________ see my website: www.geocities.com/russlk

28th October 2005, 05:40 PM	(permalink)
bloody-orc	when the track must carry large currents then a thick coat of tin is added to it. this makes the wire "fat" and therefore you dont need to have a inch wide track. it is made so in PC power suply's etc. __________________ Need Help? Press F1 If that doesn\'t help you, ask me... I might know better.