In the notes of Figure 6-4 of IPC-2221 (Conductor thickness and width for internal
and external layers), I found the following:

"3.  For general use the permissible temperature rise is defined as the difference
between the ambient temperature and the maximum sustained operating temperature of
the assembly."

Now the task... defining "sustained."

Good Luck,

Lisa Williams
IPC
2215 Sanders Road
Northbrook, IL  60062
URL:  www.ipc.org

>>> <[log in to unmask]> 06/03/98 07:16AM >>>
Greetings....

 What is the time constant for the temp vs current vs cross section charts?  I
have an application which will normally run @ 5 amps but will cycle to 200A
for up to 15 seconds about once every 5 min.

Larry Machak

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