Gary,
We use a minimum of a 0.1" breakaway to the panel edge and 0.25" between
boards on a panel. If we can we use 0.25" breakaway to the panel edge and
0.50" between boards as a standard.

Hope this helps

Ray Johnston
Lead CAD Designer
Rane Corporation
425-355-6000
rayj@rane,com

----- Original Message -----
From: "Gary M. Koven" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, August 23, 2006 8:22 AM
Subject: [DC] Breakaway tab specification


> Gentlemen,
>
> I'm looking for confirmation and/or correction on breakaway tab
> specification.
>
> On my drill drawings, this is my first note for a blanket default:
>
> "FABRICATE PER IPC-6012 CLASS 2 UNLESS OTHERWISE SPECIFIED"
>
> However, 6012 is uselessly vague about breakaway tabs...referring the user
> to the acceptability requirements of the assembly.
>
> In the Depanelization/Singulation section, I don't call out a specific IPC
> standard for breakaway tab acceptability.  The only statement I make is:
>
> "BREAKAWAY TABS MUST SHEAR BELOW EDGE OF BOARD OUTLINE"
>
> In the past, that has always been adequate.
>
> However, I now have a board for which I've been tasked to pre-determine a
> certain number of how many up.
>
> On page 35 of IPC-SM-782A, Figure 3-31 "Breakaway (routed pattern)" shows
> some better detail on their so-called Low-Stress (Mouse Bite) Breakaway.
> The figure shows approximate center to center spacing of 75mm (3.0in)
> between tabs and maximum indent of 0.4mm (0.016in).
>
> Is it kosher to call out something like this:
>
> "BREAKAWAY TABS TO BE LOW-STRESS MOUSE BITE PATTERN PER IPC-SM-782"
>
> Or, is it not kosher because there exists a different standard in the
> Acceptability series (like IPC-A-600, which I don't have here) which might
> supersede a Design-series standard such as 782?
>
> I've always in the past left arcana such as this to the assembly shop who
> typically work with their chosen fabricator to pick a panel size, how many
> up, tooling hole location, yada yada.  Now that I must own this step on
> this
> one board, I will have to issue some sort of panelization drawing, and I
> want to be careful not to put too much information on drawing which might
> add to the cost of the boards.
>
> TIA and Best Regards,
>
> ===========================
> Gary M. Koven, C.I.D.
> Dynazign, Inc.
> Charlotte, NC, USA
> Veteran of the Marsh School
>
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