Matthew,
For prototype runs and pilot runs we use a simple plastic fixture with a
milled groove the thickness of the board and the depth of the breakaway. The
operator places the edge into the grooved fixture and levers the breakaway
off. It produces a very clean break and is also very efficient. For high
volume runs, we switch to shears.
Tom Hybiske
Bose Corporation
The Mountain
Framingham, MA 01701
> -----Original Message-----
> From: Matthew Lamkin [mailto:[log in to unmask]]
> Sent: Wednesday, June 26, 2002 10:54 AM
> To: [log in to unmask]
> Subject: Re: [DC] How to break of IPC mousebyte breakaways ??
>
>
> Hi there Chris, thanks for the reply,
>
> What is puzzling me is,
> These break off tabs, when manually broken off instead of getting a
> depanelling machine
> is the stress to the board, less than cutting an ordinary
> routed tab with
> cutters?
>
> Either way I can see the board stressed, and yes placement of
> ceramic caps
> is thought about, but does
> anyone know anywhere on the net where possible studies have
> been done on
> breakoff tab stresses etc?
>
> The reason I ask this is because we do not have (and I doubt
> if we would
> get) a depannelling machine that
> will break these tabs.
>
> We do relatively small volumes and use FR4 only.
>
> Most boards get scored where possible, but some have
> overhanging connectors
> that need tabs instead
> and I want to find out the very best method of supporting
> them in the panel.
>
> Also, is there any spec on the ordinary tab, how thick the
> centre should be
> etc?
>
> Actually, thinking about it, if we were to get a depannelling
> machine, what
> sort should we get?
>
> Thankyou - Matthew Lamkin.
>
> > -----Original Message-----
> > From: [log in to unmask] [SMTP:[log in to unmask]]
> > Sent: Tuesday, June 25, 2002 2:14 PM
> > To: [log in to unmask]
> > Subject: Re: [DC] How to break of IPC mousebyte breakaways ??
> >
> > Hi Matthew-
> > Never saw a reply to this so I'll give it a go. My advice
> is; if your
> > volumes are at all significant, don't do the by-hand or pliers thing
> > unless
> > you can lay the board out such that components, solder
> joints, and small
> > traces, are REALLY far away from the breakaways. Especially
> X7R caps. We
> > recently saw a problem where a cap more than 5MM from a breakaway
> > sometimes
> > cracked even though we were using special tooling for
> singulation. Turned
> > out that it was happening during ICT due to flexing. Easy
> to fix at the
> > ICT
> > process but points out the potential for problems associated with
> > breakaway
> > tabs.
> >
> > Low tech material like CEM-1 will often delaminate badly around the
> > breakaway if done by hand (or pliers).
> >
> > We use punch and/or shear tooling, routers, or Vscore, but
> all our stuff
> > is
> > pretty high volume.
> >
> > Lastly, I've never seen a plated hole used on a breakaway tab.
> > Regards,
> > -Chris
> >
>
---------------------------------------------------------------------------------
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 set a vacation stop for delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------
|
