Two references:
(1) D.S. Peck "Comprehensive model for humidity testing" IEEE/IRPS 1986
(2) The best of THB paper I have cross: "Predicting a life of SLC/FCA
assembly by performing the accelerated stress of temperature, humidity and
voltage bias" by K. Imahara, IBM Japan, Proceeding of Stress 95 in Japan.
It detailed thermal factor, humidity factor, mechanism of moisture
absorption and influence of oxygen, and mechanical stress. The activation
energy for copper migration is 1.25 eV for the IBM SLC (FR4 based) assembly.
The data was based on 85 C/85 RH testing. You can follow the method to
obtain the Activation energy of Cu for your system (polyimide/acrylic/Cu).
(sorry, don't have the official paper).
Good luck!
jk
p.s. by the way, are you suppose on Holiday?
At 01:26 PM 12/27/99 PST, you wrote:
>Hi all,
>
> Hope everyone had a good holiday. Here's a question for you.
>
> I have completed an accelerated test to determine the voltage
>influence on electrochemical migration of copper, under 85C/85%, within a flex
>circuit. However, I have not been too successful in finding an activation
>energy from published articles for temperature. Most references go back to
>the late 70s, early 80s, but deal mainly with silver. However, I don't
>believe silver to be representative of copper. So, next I thought about the
>Conductive Filament Formation (CFF, aka Conductive Anodic Filament, CAF)
>situation in PCB. Maybe close? What do you think?
>
>Thanks everyone,
>
>Glenn
>
>P.S. I even bought ASM Vol 13 like Ingemar suggested, but not specific
>enough.
>
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