Rob,
please understand as well that your hole must be routed to make the
oval slot. Therefore you must talk with your fabricator to assure they have
a routing bit available in the correct width. Common sizes to stick to would
be 0.03125", 0.0625", 0.0935" because these are the most common routing bits
the fabricators typically (but not always) have.
One of the earlier posters 'seemed' to suggest multiple overlapping
holes, this is a definite no-no because left to that design practice your
fabricator will be sending you a very large bill for broken drill bits. In
his case the fabricator must be doing something else to deal with the slot.
As well if it was drilled that way his slot tolerances would be wildly
unpredictable because of drill wander when drilling holes which overlap.
Have you ever tried drilling a hole that half overlaps with an existing
hole, good luck and you had better be wearing ear protection.
My methodology is similar to other suggestions. I use a pad of the
size I want for the copper area around the slot, possibly this is routed
away or slightly larger then the slot. The pad may be rectangular, oval,
round, plated or unplated depending on what I want for copper. I then will
typically make the hole size something very small (i.e. 1 mil, something
that is undrillable). I use fabrication drawings so on the fabrication
drawing I call out the correct slot size and orientation for all holes 1 mil
in diameter using a detail view. Remember that you must show the correct
orientation of your slots for each occurrence on the PCB. You probably don't
want the slot always vertical or horizontal. If I have more then one slot
size or to show a different orientation I may use 2 mils for the next slot
variation, etc., etc..
Brad Velander,
Lead PCB Designer,
Norsat International Inc.,
#300 - 4401 Still Creek Dr.,
Burnaby, B.C., V5C 6G9.
Tel. (604) 292-9089 direct
Fax (604) 292-9010
website www.norsat.com
> -----Original Message-----
> From: Richard Barsczewski [mailto:[EMAIL PROTECTED]]
> Sent: Wednesday, June 27, 2001 6:07 AM
> To: Protel EDA Forum
> Subject: Re: [PEDA] AW: Pad With Slotted Hole
>
>
>
> Rob,
>
> We do this quite often to attach covers to boards. We use this
> procedure after discussions
> with our vendors. We put a pad and hole (corresponding
> to the slot
> width) at each end of the slot
> and then add the dimensions for the slot on the
> fabrication drawing.
> If you want the slots plated thru,
> make the end pads and connecting trace the appropriate size for
> proper copper width around the slot.
> If the slots are not plated thru, put a pad diameter
> that will be
> routed away.
> I believe this was all mentioned already, but anyway,
> that's how we
> do it.
>
> Richard Barsczewski
>
>
> > -----Original Message-----
> > From: Georg Beckmann [SMTP:[EMAIL PROTECTED]]
> > Sent: Wednesday, June 27, 2001 6:09 AM
> > To: 'Protel EDA Forum'
> > Subject: [PEDA] AW: Pad With Slotted Hole
> >
> > Hi Rob,
> >
> > The most simple way is to set the hole at the centre or at one side
> > of the slot with the slot small-side diameter. Add the
> outline of the slot
> > on a mechanical-layer and make a comment for the board-maker.
> >
> > I'm not sure, if there are special design rules for plated slots.
> > I suggest to ask the boardmaker for that.
> >
> > Georg
> >
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