totally agree.  Unless you got resistivity increase....
                                               jk

>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]]On Behalf Of Tim Reeves
>Sent: Monday, September 16, 2002 2:39 PM
>To: [log in to unmask]
>Subject: Re: [TN] request of formula of calculation of impedance after
>thermal shock
>
>
>I don't think thermal shock testing is supposed to have any
>appreciable (certainly not any predictable) effect on impedance.
>If it does, there's something wrong with the board to begin with.
>T. Reeves
>
>-----Original Message-----
>From: Jack Low [mailto:[log in to unmask]]
>Sent: Sunday, September 15, 2002 9:51 PM
>Subject: 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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