Copper weight and size
What weight and sixe of copper will I need to withstand said a surge current of 10KA, 20KA or 30KA for PCB board design?
Thanks
Calvin
Thanks
Calvin
08/08/2002 16:38:10
Sujet: Copper weight and size
Re: Copper weight and size
: What weight and sixe of copper will I need to withstand said a surge current of 10KA, 20KA or 30KA for PCB board design?
:
: Thanks
:
: Calvin
Hi Calvin,
Thanks very much for your question, and we hope the answer provided will help you out.
The number of variables for calculating what current a track can withstand depends on a huge amount for variables.
If you are not using high frequencies at high currents, then the greatest factor limiting the track thickness is ?Ohmic Heat?. In essence the heating of the track against the ability of the track to cool itself. It follows that the outer tracks will cool at a faster rate than the inner layer tracks, should the PCB be a Multi layer.
One Should also remember that a continous current will be more beneficial to a tracks lifetime, than when the current through the track oscillates causing repeated expansion and contraction.
Assume the following:
The copper thickness on the PCB is 35?m, the rise in temerature is approximately 10°C, and the tracks are alone, i.e, not near a heat sink.
It follows:
Track width: Current capacity:
0.25mm 0.8 Amps
0.5mm 1.5 Amps
1.27mm 3.2 Amps
2.5mm 6.0 Amps
Some rules of thumb:
To increase the capacity of current in the track by a factor of the square root of 2
( ca 1.4) you should double the track thickness. You can use the power rule I? = W/R.
To increase the capacity of current in the track by a factor of approximately 1.65
you should double the track width.
For saftey reasons one should always derate the practical values compared to the theoretical values.
There is another formula that maybe used for more prescise calculations
0.44 0.725
I = 0.048 T A
Where I = Current in Amps / T = temperature rise in °C / A = Cross section area in mils?
Please see the link below to find the Current Capacity Calculation formula of Beta LAYOUT GmbH
Thanks again
All the Best
Your Beta LAYOUT Team
:
: Thanks
:
: Calvin
Hi Calvin,
Thanks very much for your question, and we hope the answer provided will help you out.
The number of variables for calculating what current a track can withstand depends on a huge amount for variables.
If you are not using high frequencies at high currents, then the greatest factor limiting the track thickness is ?Ohmic Heat?. In essence the heating of the track against the ability of the track to cool itself. It follows that the outer tracks will cool at a faster rate than the inner layer tracks, should the PCB be a Multi layer.
One Should also remember that a continous current will be more beneficial to a tracks lifetime, than when the current through the track oscillates causing repeated expansion and contraction.
Assume the following:
The copper thickness on the PCB is 35?m, the rise in temerature is approximately 10°C, and the tracks are alone, i.e, not near a heat sink.
It follows:
Track width: Current capacity:
0.25mm 0.8 Amps
0.5mm 1.5 Amps
1.27mm 3.2 Amps
2.5mm 6.0 Amps
Some rules of thumb:
To increase the capacity of current in the track by a factor of the square root of 2
( ca 1.4) you should double the track thickness. You can use the power rule I? = W/R.
To increase the capacity of current in the track by a factor of approximately 1.65
you should double the track width.
For saftey reasons one should always derate the practical values compared to the theoretical values.
There is another formula that maybe used for more prescise calculations
0.44 0.725
I = 0.048 T A
Where I = Current in Amps / T = temperature rise in °C / A = Cross section area in mils?
Please see the link below to find the Current Capacity Calculation formula of Beta LAYOUT GmbH
Thanks again
All the Best
Your Beta LAYOUT Team
09/08/2002 16:27:57