After reading my reply once more I realized I left out a detail... in order
to make the gap thinner here we have to use a thinner cutter blade on our
depanelizing tool, one that matches the gap in the panel. It's a custom made
cutter but they aren't very expensive to make, they are tooled out of sheet
metal steel and shaped like a 1 inch by 3/4 inch hook. The pneumatic
cylinder that pulls it down against the work surface and through the board
web cuts right through the board like butter and is very strong and operated
with a foot pedal. The board is very cleanly sheared and creates no dust
like the router bit or Dremel tool abrasive wheel cutter versions I have
seen. It's actually a very efficient way to deal with the issue.
Bill Brooks - KG6VVP
PCB Design Engineer , C.I.D.+, C.I.I.
Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510
e-mail:[log in to unmask]
http://www.dtwc.com
http://pcbwizards.com
-----Original Message-----
From: Brooks,Bill [mailto:[log in to unmask]]
Sent: Wednesday, January 26, 2005 8:46 AM
To: [log in to unmask]
Subject: Re: [DC] Web routing widths
Hi Gary,
Here we chose a .100 in. wide gap between the board and the panel with a web
that is .100 in thick plus or minus .020 in. The reason for that choice was
based upon 2 factors. One, the board house that manufactures our board likes
to do the panel gap with a single pass of the router bit and they prefer the
.100 wide gap so they can use a larger router bit. If I had a board that has
need of a smaller radius on right angle cuts than .050 in. I would probably
reduce the gap to let them make the run with a single pass and a smaller
router bit. The second criteria for driving the decision to us .1 and .1 is
our assembly group uses a 'depanelizing' or 'singulation' tool that is
optimized for the .100 width web... It was designed to be used similar to a
sheet metal 'nibbler' tool and cut the web out in a single hit. The width of
the cutter just fits into the slot between the boards leaving very little
flash after the cut is made.
There are many other methods of depanelizing boards and those methods should
be taken into consideration when design your assembly panel.
There are actually some IPC guidelines published in IPC-SM-782 section
3.6.4.6. Figures 3-29, 3-30, 3-31 and 3-32 give good examples of assembly
panel construction. I think you will find them informative. If you have
taken the CID workshop and exam you will find the info on page 117 and 118
of the Study Guide.
Best regards,
Bill Brooks - KG6VVP
PCB Design Engineer , C.I.D.+, C.I.I.
Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510
e-mail:[log in to unmask]
http://www.dtwc.com
http://pcbwizards.com
-----Original Message-----
From: Gary Koven [mailto:[log in to unmask]]
Sent: Wednesday, January 26, 2005 8:00 AM
To: [log in to unmask]
Subject: [DC] Web routing widths
Forgive me if this seems arcane, but we've become interested in the
different web routing widths that our assemblers are telling their
fabricators to use to panelize/depanelize our boards. We've seen 0.125
inch, 0.093 inch, 0.062 inch, and 0.050 inch wide webs thus far.
1. Is there one IPC standard, or a combination of IPC standards, which
specifies preferred web routing widths?
2. How does an assembler determine a "sweet spot" for each preferred web
routing width whereby the individual boards will depanelize most easily?
3. Which preferred web routing width yields the lowest cost route?
Best Regards,
======================
Gary M. Koven, C.I.D.
Engineering Services Manager
Dynazign, Inc.
806 Tyvola Road, Suite 100
Charlotte, NC 28217
P: 704.405.1234 x210
F: 704.405.1402
http://www.dynazign.com/
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