Jack:

Characteristic impedance shouldn't change from a thermal excursion or
thermal shock.  There are many sources for online impedance calculators
including www.polarinst.com and www.idc.com.au.  You can find other
refernces to calculators in the technet archives.

Don Vischulis

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Jack Low
Sent: Sunday, September 15, 2002 11:51 PM
To: [log in to unmask]
Subject: [TN] request of formula of calculation of impedance after thermal
shock


Dear all:
 we would like to know  the formula to calculate the impedance before
thermal shock abd after thermal shock  on PCB,
and where can I find out the formula to calculate in IPC, any suggestions
and nformation will be sincerely appreciated,Thanks a million!   Have a nive
day!

Best regards

Jacl low

[log in to unmask]

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