Hi George! I would be very interested in seeing the rationale why
microsectioning would not be a valid methodology for evaluating microvias.
Microsectioning does have its limits but there are specific practices and ASTM
specifications that make the methodology a valid engineering tool. Then again,
being a metallurgical engineer and having practiced microsectioning for 17 years
I could be a bit biased! Did the HDI statement maker backup his/her rationale
for why microsectioning could not be applied to the evaluation of microvias with
any data?

Dave Hillman
Rockwell Collins
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Gfranck <[log in to unmask]> on 12/09/99 08:19:02 AM

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Subject:  [TN] microsectioning microvias in general



Susan M, and Technet at large,

Iis there any evidence that microsectioning is a valid method of determining the
quality of micro vias?  (Except for the "this is what we have always done"
argument.)
A statement was made at the recent HDI conference in Austin TX that it was not.

Of course that did not prevent anyone from pulling out their pictures of Cross
Sections
during the 'show and tell' time.

George Franck
Raytheon Company

[log in to unmask] wrote:

> Pins are nice and work really well for larger holes BUT with the microvias
> they probably won't serve the same purpose or success.
>
> The reason for this is that the center lines of the vias are rarely the same -
> to me that is one of the main problems -
>
> In a row of microvias you may be able to look at one at a time due to the
> slight misregistration of position.
>
> We use pins (2) - we drill their location with an Excellon Unidrill - but do
> not
> rely on all vias coming into view at the same time.
>
> Susan Mansilla
>

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