Matt,

We have experimented with laser with mixed results: on one occasion we were
attempting to cut a connection approximately 5 mils under the surface of the
board (FR4 material), that worked out very well.

Another time we were trying something a little more daring, cut out a
clearance from a power plane 6 layers under the surface, approximately 30
mils down. That one didn't go that well, the 1 mil laser beam that we were
using was able to cut to the required depth but the 30:1 aspect ratio of the
cut caused, I think, a carbon re-deposition along the walls of the cut.
That gave us a high resistance short that was impossible to remove.

I would like to add that both times we were performing the operation under
the direction of our customer to fix a design problem, I'd like to stress
that because I'm pretty sure that this kind of "repair" would not be
permissible without proper authorization.

Chicco Vigano
Compunetics, Inc.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Matt Cirineo
Sent: Wednesday, November 03, 1999 5:28 PM
To: [log in to unmask]
Subject: [TN] Cutting through an inner trace


Other than drilling, has anyone used an alternative method of cutting
through an inner layer trace?  I'm thinking of methods such as laser, water
cutting,...

Your comments and suggestions would be greatly appreciated.
Matthew Cirineo
Operations Engineering
Primex Aerospace Company
phone: 425-885-5010 x4855
fax: 425-895-4310

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