As Steve says, there's no one answer. Ceramic caps perpendicular to the
singulation point (tab, Vscore, whatever) crack more easily than a
resistor, etc... Routing the tabs seems to induce less stress than other
methods, but we've occasionally had issues with routed boards in high
volume. If the tooling is set up properly (Wand Tool does good work), you
can punch tabs with components fairly close....
I worry about it on a priority basis. If the component density isn't
ridiculous, I make an optimal array and place parts respecting the tab
locations. If I'm not even sure I can fit the parts, I kinda try to worry
about it all at once, with singulation being a lower priority than layout.
Depending on who is building the boards and what kind of volume you're
dealing with, you really have a lot of options.... there's always a way.
-Chris
"James, Ron CAR"
<[log in to unmask] To: [log in to unmask]
> cc:
Sent by: DesignerCouncil Subject: [DC] Spacing between SMT and
<[log in to unmask]> breakaway
04/04/2005 04:43 PM
Please respond to
"(Designers Council
Forum)"; Please respond to
"James, Ron CAR"
IPC-7351 discusses V-score and "mouse bite" breakaway
patterns, but I can't find a recommended spacing between
those and SMT parts. Does this exist in another IPC spec?
Or can anyone provide the benefit of their experiences?
In-house we specify .200" clearance from v-score, but have
nothing formal for the tabs. The mouse-bite breakaways
are called "low stress", so I am hoping to place the SMT
parts closer than with v-score.
Thanks for any pointers,
Ron James, C.I.D.
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