>We are working on a laminate package product in which we wish to embed Alloy
>42 or Kovar layers.

Kovar might be easier.


>We also need to make PTH contact to these layers.

Direct plate (carbon) would be more straight forward than electroless. You can
probably just use a new microetch (low copper) without substituting a ferric
based process in that line and the same in pattern plate.


>These PTHs also need to be somewhat high aspect ratio, at least 8:1 and
>desirably more than 12:1. Fortunately, the hole sizes are fairly large
>though, i.e. 0.015" to 0.030".

Better you than me. :^)


>We have though seen some difficulty in drilling in that there seems to be
>excessive "nail heading" and sometimes the bits seem to "wander" excessively
from the top to the bottom of these boards.

Sounds like a good candidate for peck drilling stopping each peck after a
Kovar plane. Try Feeds & Speeds near the CNCs minimum & 0.3 mil chip at the
0.015" size.

Good luck!


Tom Waznis

***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To subscribe/unsubscribe send a message <to: [log in to unmask]>   *
* with <subject: subscribe/unsubscribe> and no text in the body.          *
***************************************************************************
* If you are having a problem with the IPC TechNet forum please contact   *
* Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask]      *
***************************************************************************