Is your trace internal or external to the layers (exposed to air or not...)

There's a really great calculator for this sort of problem on-line that I
have a link for on my website...Developed by Brad Suppanz and based on Doug
Brooks' (no relation) calculations in his article on "Temperature Rise in
PCB Traces"... it says 5 amps with a 20 deg rise over ambient, 1 oz. copper
You need a 69 mil trace on external layers... but on internal layers you
need 212 mils... This would affect the performance of the conductor... I
have never heard of a broken trace referred to as 'electron migration',
sounds like a electroplating term having to do with galvanic reactions
between dissimilar metals more than a meltdown of a trace due to excessive
current and heat...
But I think I understand what you are talking about...
So it matters, whether or not you are using this trace internal to the board
or external... Does that help at all?

Bill Brooks
PCB Design Engineer
DATRON WORLD COMMUNICATIONS INC.
3030 Enterprise Court
Vista, CA 92083
Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510
mailto:[log in to unmask]
IPC Designers Council, San Diego Chapter
http://www.ipc.org/SanDiego/
http://home.fda.net/bbrooks/pca/pca.htm



-----Original Message-----
From: Amira Mohammed [mailto:[log in to unmask]]
Sent: Sunday, February 25, 2001 1:35 AM
To: [log in to unmask]
Subject: [DC] Trace width


Dear all,

I have a question about how we can calculate practical values for trace
width.
In IPC-D-275 there is a chart for this, but when I used it I felt the value
is not practical.for example when I have 5 Amp current flow in a trace
cusing tempreture rise 20 and 1oz/ft2 the width is about 0.07in ,additionaly
when this take place we have an electron migration problem (trace is
broken),so can any one help me?

thanks in advance
with best regards

Amira Mohamed
PCB Designer
IEP
www.bahgat .com

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