Scoring allows more boards in a panel, but ceramic chip parts to tend to
crack when the boards are separated unless they are kept a good distance
(150 MIL [8.6 mm] or more) from the score line or the score line has a row
of small unplated drill holes along it to reduce stress when the cutter
breaks the boards apart.
Routed boards have more wasted space on the panel and require keep-outs
around the "tabs" that hold the boards to the panel and each other, but
allow parts much closer to the edge of the board.
Which method we use depends on the type and density of the board.
--
George Patrick
Tektronix, Inc.
Central Engineering, PCB Design Group
P.O. Box 500, M/S 39-512
Beaverton, OR 97077-0001
Phone: 503-627-5272 Fax: 503-627-5587
http://www.tektronix.com http://www.pcb-designer.com
It's my opinion, not Tektronix'
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Matthew
Lamkin
Sent: Thursday, January 27, 2005 06:36
To: [log in to unmask]
Subject: Re: [DC] Web routing widths
We have some hand tools similar, however I think that the women on the shop
floor find it hard to operate (needing bigger hands to use it) so they
prefer to use wire cutters instead.
Our gaps are usually set at 2.5mm as that's the std router bit size of our
manufacturer & the webs are usually 1mm at the thinnest part of the curve.
We tried the IPC mouse byte's but out production dept don't seem to like
them, they think they cause more stress than cutting tabs.
Do you prefer routed boards over scored at all?
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]]On Behalf Of
Brooks,Bill
Sent: Wednesday, January 26, 2005 4:46 PM
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/
----------------------------------------------------------------------------
-----
DesignerCouncil Mail List provided as a free service by IPC using LISTSERV
1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
To temporarily stop/(restart) delivery of DesignerCouncil send: SET
DesignerCouncil NOMAIL/(MAIL)
Search previous postings at: www.ipc.org > On-Line Resources & Databases >
E-mail Archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16
for additional information, or contact Keach Sasamori at [log in to unmask] or
847-615-7100 ext.2815
----------------------------------------------------------------------------
-----
----------------------------------------------------------------------------
-----
DesignerCouncil Mail List provided as a free service by IPC using LISTSERV
1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
To temporarily stop/(restart) delivery of DesignerCouncil send: SET
DesignerCouncil NOMAIL/(MAIL)
Search previous postings at: www.ipc.org > On-Line Resources & Databases >
E-mail Archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16
for additional information, or contact Keach Sasamori at [log in to unmask] or
847-615-7100 ext.2815
----------------------------------------------------------------------------
-----
----------------------------------------------------------------------------
-----
DesignerCouncil Mail List provided as a free service by IPC using LISTSERV
1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
To temporarily stop/(restart) delivery of DesignerCouncil send: SET
DesignerCouncil NOMAIL/(MAIL)
Search previous postings at: www.ipc.org > On-Line Resources & Databases >
E-mail Archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16
for additional information, or contact Keach Sasamori at [log in to unmask] or
847-615-7100 ext.2815
----------------------------------------------------------------------------
-----
---------------------------------------------------------------------------------
DesignerCouncil Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
To temporarily stop/(restart) delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL/(MAIL)
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
---------------------------------------------------------------------------------
|
