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Date: | Fri, 2 May 1997 15:44:39 -0500 |
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Ed,
I think scoring is great, especially where array profiles are
required. Your design must sometimes include tooling holes in certain
locations to accomodate some scoring machines or the panel at the Fab
house will provide them. What I focus on most is the residual
material following scoring. I use scoring on both our wired and
wireless products. Although a great IDEA, our PCMCIAs (wireless) can
not be scored due to the type of Can it is inserted into. Scoring
still does not cut the board profile (Z-axis) straight without cutting
into the meat of the PCB. The residual amount is also critical from
the Assembly point. If there is not enough material remaining and
your board spans a great distance in all directions, it may cause
problems in component seating.
I've recently seen Floating Head Score Machines, that unlike existing
score machines will not score all the way to the panel edge, which
allows for more Z-axis rigidity in the panel.
Your residual will vary going from .062 to a .093 or .0785, with such
variables as laminate, copper weight, copper planes, etc. You will
have to look at your overall material recipe in addition to the type
of components that are be placed to where they are being place to
determine the amount residual. The angle you have chosen is typical
with most scores and can be kept.
One other important note is how will the panel be depanelized. The
method in which you depanelize your boards from the array is critical
to the functionality of the final assembly. Gull wing packages,
components close to the edge, mis-oriented components (DFM), etc can
cause problems when hand depanelizing. You may have to use a PIZZA
cutter to effectively depanelize the boards from the array and even
that gets tricky.
Which now leads us back to routing. Routing is like one stop
shopping, its quick and very cost effective. 99.9% of all PCBs have
to visit the Route Dept. at some time in the process. You can stack 2
to 4 panels while routing. One less set-up then scoring, etc, etc.
Its brief but I hope it helps.
John Gulley - Process Quality Engineer
Inet Inc.
972-578-3928
______________________________ Reply Separator _________________________________
Subject: FAB - Scoring PCB panels
Author: Ed Gavin <[log in to unmask]> at Internet
Date: 5/2/97 10:04 AM
On 0.062 inch thick boards, we currently call for a 30 degree score,
0.020 inch deep on opposing sides of the board.
We are trying to develop our standard for scoring. Is this what most use
for scoring?
Do you score boards thicker than 0.062 and if so what dimensioning do
you use for those?
If given the choice would you select scoring over routing? why?
Thought this might be of general interest to the board community.
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