Our recommend web would be .012 +/- .003 in your situation.
Cliff
Cliff Lamson
PCB Design Manager
Project Manager
PLEXUS Technology Group
Raleigh Design Center
5511 Capital Center Drive, Suite 600
Raleigh, NC 27606
Main 919-807-8000
Direct 919-807-8047
Mobile 919-649-3159
Fax 919-807-8190
The Product Realization Company
www.plexus.com
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Gary
M. Koven
Sent: Thursday, August 16, 2007 12:05 PM
To: [log in to unmask]
Subject: [DC] V-scoring and web thickness
I'm preparing a panel layout drawing.
For purposes of this post, all dimensions are in inches.
Material is 0.062 FR-4
Panel size is 12.000 X 8.500
Board size is 1.000 x 0.625, 120 boards per panel
I want to v-score these boards for "easy manual singulation" and would
like to put a note on drawing to make sure the cuts are deep enough.
Now then,
READILY AVAILABLE REFERENCES
1) Apart from IPC-2222 Table 5 general parameters there appears to be no
other official IPC publications describing preferred web thicknesses.
2a) The best Internet reference I've been able to find is here:
http://www.tkb-4u.com/articles/other/vscore/vscore.php
2b) According to the matrix within this article, for a panel 10 to 15
inches long and individual PCB 1.0 long, I should recommend 0.010 web
thickness.
3) According to the LISTSERV archives, in message 006509 back in 2001,
my old colleague Ed Valentine (now retired) recommended 0.012 web
thickness for easy manual breakaway.
CONCLUSION
So if I didn't know any better and if nobody answers this, I'd end up
with a drawing note something like this:
"V-SCORE TO FINAL WEB THICKNESS OF 0.012" +/- 0.002" USING 30 DEGREE
CUTTERS"
I'm going to call some fab folk to get their take, but meanwhile, your
assistance here is kindly appreciated.
Thanks and Best Regards,
----------------------------
Gary M. Koven, C.I.D.
Dynazign, Inc.
Charlotte, NC, USA
704.405.1234
Veteran of the Marsh School
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