In a message dated 04/03/2001 17:44:22, [log in to unmask] writes:
>Again, thanks for your take on the situation.
>I read IPC-2222, but it did not appear to address the issue of
>delineation between aspect ratio-ed vias which require
>a minimum of 0.00079 inch and 0.00040 inch of copper.
>If a spec is written-up and accepted by the industry,
>the delineation between one aspect ratio and another should be too.
>Or do I continue to flounder?

Hi Mike,
Being a commercial laboratory, you only need to report the results you find;
you do not need to interpret them either as to their meaning in
reliability-terms, nor as far a specs are concerned. Your customer needs to
make those decisions, perhaps with the help of a consultant.
When the specs were changed from 1 mil to 0.8 mils minimum, I expressed my
concerns about the possible reliability consequences to the committee. The
driver for that change was of course economic. Plating 1 mil Cu at 13 Asf
takes twice as long as with the previous 25 Asf. Now, there may be Cu
property improvements warrenting thinner plating, but the data showing this
are not in the public domain if they exist at all.

Werner Engelmaier

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