Hi Kevin,
We use dedicated fixtures to elevate boards off the table rather than a
sacrificial material on the bottom. That only works for high volume
where the cost of the fixture and storage are less than the cost of the
sacrificial material. Also, it is common for PCB suppliers to sandwich
the boards with top and bottom materials to prevent burrs along edge
connectors. Again, the cost of customer returned product vs. the cost
of the sacrificial material needs to be weighed against each other. By
the way, clean cuts can be made WITHOUT using a sacrificial material on
top by employing double cuts, cut direction, reduced router bit life,
optimized spindle speeds, optimized feed rates, and optimized bit
shapes, etc; all of which needs to be weight against costs. But, that's
what you were hired to figure out, (and, like race car engines, I've
never seen a shop that wasn't continuously trying to tweak and figure it
out)...
-Ryan
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Kevin Glidden
Sent: Wednesday, April 05, 2006 7:41 AM
To: [log in to unmask]
Subject: [TN] ANOTHER pcb fab question...
As I walk farther down the PCB fab road, more and more questions come
up...Thanks to all in TN who are helping me out to learn more...
This question has to do with PCB routing. When the PCBs are routed out
to
final size, is it normal to use both a top and bottom "material" to
ensure
the PCBs are flat and to ensure a clean cut? I can guess that a bottom
material is necessary just to avoid cutting the table. What are the
materials for this support material that is really sacraficial? Who are
the
suppliers?
Thanks again...
Kevin Glidden
Manufacturing Engineer
Luminescent Systems Inc.
4 Lucent Drive
Lebanon, NH 03766-1439
Tel # (603) 643-7766 ext. 3152
Fax # (603) 643-5947
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