http://www.pcb-designer.com/trace.html
--
George Patrick
Tektronix, Inc.
Central Engineering, EDS Applications Support
P.O. Box 500, M/S 39-512
Beaverton, OR 97077-0001
* 503-627-5272 (voice) * 503-627-5587 (fax)
http://www.tektronix.com http://www.pcb-designer.com
"Off-Grid and Proud of it!"
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of
Brooks,Bill
Sent: Tuesday, May 08, 2007 15:39
To: [log in to unmask]
Subject: Re: [DC] Current Capacity of Thermal Reliefs
Dave,
You will find the formulas for isothermal relief for through hole lands
in
the IPC-2222 section 9.1.2 Thermal Relief in Conductor Planes.
Basically it tells you to use 60% of the land size as the 'thermal
width'
and then divide it up equally by however many ties you require. The gap
between the pad and the plane can typically be near the same width as
the
web connection width unless you are dealing with some voltage spacing to
another conductor which is a different matter all together.
Regarding the current... if you have four .025 in. wide ties to a land,
you
would add them together to be equivalent to a .100 in. trace. Figure out
what the current carrying capacity is for a .100 in. trace of the copper
at
the thickness you are using and you will be very close.
Also the copper in the hole, if that is your application, can be
calculated
by converting the hole into a trace... just imagine splitting the barrel
of
the hole longwise and flattening it out... you then have a sheet of
copper
equivalent to the width and length of the rectangle by the thickness of
the
plating in the hole... It's not really rocket science... but you do have
to
use Pi in the calculation. :)
I don't know of a calculator for that task but is sounds like a great
project. Any ambitious programmers out there want to take it on?
Best regards,
Bill Brooks
PCB Design Engineer, C.I.D.+
Tel: (760)597-1500 Fax: (760)597-1510
Datron World Communications, Inc.
Vista, California
-----Original Message-----
From: David Baldwin [mailto:[log in to unmask]]
Sent: Tuesday, May 08, 2007 2:35 PM
To: [log in to unmask]
Subject: [DC] Current Capacity of Thermal Reliefs
Is there a calculator for the current carrying capacity of a
component thermal relief?
Thanks,
Dave
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