Hello Amira,
There have been some good references to calculators on the net. For example,
Bill Brooks' site, and also the Doug Brooks article. (many are based on the
IPC charts, so apply to steady state or rms ac values)

http://home.fda.net/bbrooks/pca/pca.htm

Looks like your maximum surge current needs to be taken into account here.
This could be very large with large capacitive loads.
Heat energy takes a finite time to be absorbed by the copper, so the effects
depends on the time duration of the surge. I'm no physicist, so can't help
you much here.
Just an idea, but perhaps the design can be altered to limit this initial
surge current?

regards,
Phil.

-----Original Message-----
From: Amira Mohammed [mailto:[log in to unmask]]
Sent: Monday, 26 February 2001 20:09
To: [log in to unmask]
Subject: Re: [DC] Trace width


        Dear Phil and Gary,

        Thank you for both of you
You are right .When I've asked about this,I told  that we want some safty
factor for surge current , so should I calculate the trace width depending
on the maximum current value may be take place due to surge current, or
there is another way to calculate it?
Thanks in advance
Regards,

Amira Mohamed
PCB Designer
IEP
www.bahgat .com

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