Hi all,

Thanks Bill for the copy of the presentation.

We are currently designing a 16 layer PCB with through hole vias, that we
have to attach a 1200 pin, 1mm pitch, full array device to. The stackup
actually looks pretty close to the one on page 12 of the presentation.
This design is a is a first for us, and from the information contained in
the presentation, it looks like we are heading down the right track. The
cost adders for HDI made for interesting reading.

I am not wanting to cause trouble before Mr Shoot gives his presentation,
but I have a question regarding the use of the 3 mil prepregs shown in the
stackup on page 12 of the presentation.  I would assume that this would be
one prepreg thickness only. I have had feedback from our board suppliers,
and have been on courses, that say that it is preferable to lay up 2
prepregs. (This is to avoid potential shorts?). I will be asking our
suppliers this question too, up to now this has not been an issue.

Any does anyone have any comments on this? Will using one prepreg cause
problems?

(Our stackup came to around 70 mil thick, with 10 mil drilled holes,
therefore aspect ratio = 7:1, so is manufacturable, we are still discusing
details with our suppliers)

Regards,

Steve.
-------------------------------------------------------
Steve Kingdon            27 Nazareth Avenue
PCB Layout Engineer      PO Box 8011
Allied Telesyn Research  Christchurch
phone +64 3 339 9223     New Zealand
fax   +64 3 339 3002
email: [log in to unmask]
web: http://www.alliedtelesyn.co.nz/
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