Hi Ian,

I've not recognized, that Ivan wants to route connections across the
break-line. I think it's not a good idea to make the connections  on inner
layers
and a V-cut on the outside. The risk, that the V-cut is a bit to deep is
high.
Any other methode drilling holes, cut slots a.s.o. makes the board weak at
this line
and there is a risk that the traces break sooner or later. I just wouldn't
use this
technic in the case that traces are needed to the breakout an would think
about
something else to use.

Georg

-----Ursprungliche Nachricht-----
Von: Ian Wilson [mailto:[EMAIL PROTECTED]]
Gesendet: Mittwoch, 26. Juni 2002 01:43
An: Protel EDA Forum
Betreff: Re: [PEDA] AW: PCB breakoffs


On 11:55 AM 25/06/2002 +0200, Georg Beckmann said:
>If the breakaway is a straight line over the whole board, I suggest a V -
>cut
>from both sides. V cuts can only be made over the whole length. If it is a
>rectangle
>inside the main board, ( like TV main board and CRT driver board ) you can
>mill slots
>around and (live)  leave some small bridges. This board is cut out
ter.   ----
>
>All you need to do is to draw this on a mechanical layer an the board maker
>will do the milling.
>A V cut can be about 0.2 .. 0.3mm, milling slots should be 2 .. 3 mm.

Bit hard to run the tracks across the V-Groove though ... V-grooving is
really only useful when it runs the full length of the board.  In the
situation that Ivan asked about he wants to connect the optional circuit
with tracks (through the break off tab).

I have seen what Ivan was proposing done but it is a little ugly and unless
the tracks crossing the boundary are thin or the tracks are first scored
with a knife you can get a slightly untidy break pattern on the tracks and
surrounding resist.  But scoring with a knife worked for us and ours was
only a very small volume test jig anyway.

Mouse bite breakoffs always leave a bit of dagginess - I usually make the
breakoff quite heavily curved (into the board) and push the rout into the
board a small distance to ensure the break off does not leave anything
proud of the board edge.  Polishing rough edges with a file post snap-off
is another operation that increases cost (but makes the board look better).

Ian Wilson


>Georg
>
>-----Urspr ngliche Nachricht-----
>Von: Bagotronix Tech Support [mailto:[EMAIL PROTECTED]]
>Gesendet: Montag, 24. Juni 2002 21:16
>An: Protel EDA Forum
>Betreff: [PEDA] PCB breakoffs
>
>
>Hello, all:
>
>We have had our domain transferred to a new ISP last week, so e-mail has
>just begun working normally (I hope!).
>
>Anyway, I want to make a PCB that has a "break-off" area with extra
>circuitry on it.  The idea is that some users may not need the extra
>circuitry, so they can break off that area of the board to reduce the size.
>I know this is easy for cheap PCB material (phenolic, etc.) but does this
>work with FR-4 and such?
>
>If this is feasible with FR-4, what technique should I use to make the
>break-off?  I assume I will have to lay out a bunch of unplated holes
spaced
>in a line, with traces going inbetween holes.  And I assume that the way to
>indicate this to the fab is to put comments on the drill layer.
>
>Thanks in advance for your help.  If no one replies, I will assume our
>e-mail still isn't working right.
>
>Best regards,
>Ivan Baggett
>Bagotronix Inc.
>website:  www.bagotronix.com
>
>
>
>
>************************************************************************
>* Tracking #: E0D56A16817ACA4091A0139DC100BD9938215AA3
>*
>************************************************************************
>



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