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June 2000

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Subject:
From:
Tom Martin <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 22 Jun 2000 12:10:52 -0400
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Just curious Mark,

What are the problems with "replacing small holes
with score lines on tab rout designs?"  I
once had a manufacturing engineer request that an
array panel be done this way and the results appeared satisfactory.

Tom Martin



Date:    Thu, 22 Jun 2000 08:58:55 -0700
From:    Mark Simmons <[log in to unmask]>
Subject: Re: V-score depth
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Dennis, Steve, et al....

i suspect the reason this topic keeps coming up is because of our well
intended desire
to  nail things down.  after all, there are so many things to keep track
of, eh?

By way of review,...there are too many variables to be specific about what
the
remaining core thickness (web) should be.  the chart that Steve recommended
from the
Accusystems web page, takes into consideration the most variables, but
still makes many
assumptions. i.e.; the material is FR4, and the score line is not adjacent
to SMT
component lands. So this chart will get you into the ball park, but you
must find your
own seat.  Here at Vscore Central, we deal with these issues on a daily
basis...over
the years, we have seen some pretty strange stuff.  There is an astonishing
lack of
convention.  There are a number of mis-applications, including replacing
small holes
with score lines on tab rout designs. Simple things like providing solder
mask
clearances for the score lines are overlooked. (acrylic masks machine so
poorly..)
Generally, the process is an afterthought (at best) for most
designers...but i
digress.  In summary, be careful with "rules of thumb".

Mark Simmons, V-Score Central, Inc.

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