PCB holes overlapping

[Spehro Pefhany]

Is this generally acceptable? I want to overlap two of 0.136" holes by
about 0.024" in several places. They are plated with no electrical
function.

Thanks!

Best regards,
Spehro Pefhany

 

[Leon Heller]

Is this generally acceptable? I want to overlap two of 0.136" holes by
about 0.024" in several places. They are plated with no electrical
function.

Thanks!

Best regards,
Spehro Pefhany

http://www.speff.com

One supplier I use for prototype PCBs (PCB-Pool)assumes that overlapping
holes are slots to be routed. I don't think that PCB manufacturers would
like actual overlapping holes as they might break their drills.

Leon

 

[Boris Mohar]

Is this generally acceptable? I want to overlap two of 0.136" holes by
about 0.024" in several places. They are plated with no electrical
function.

Thanks!

Best regards,
Spehro Pefhany

Because the holes rather large compared to overlap you can probably get away
with it. Check with your board manufacturer.

--
Boris Mohar


Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca

 

[Brad Velander]

Spehro,
Do you want a slot or a figure eight shape?

I always use one of either two methods for such things.
1) I use a unique hole size for one pad, 1 - 5mils, something
they cannot attempt to drill. Then do a note referencing that
drill size and a small drawing outlining the shape and dimensions
based upon the unique hole size being the center of one of your
lobes.
2) If it is a slot, then I usually use a mechanical layer to
draw the shape I want in the correct location and orientation.
Then reference it in your notes telling the fabricator that this
shape is desired and that it is plated. Make sure there is some
common reference between layers so that a Gerber set aligns the
detail precisely where you want it and in the correct orientation
on the PCB.
I have also give these details on multiple layers with the
lines actually including an offset for appropriate router bit
diameters that I know the fabricator has. Theses layers are then
just a router centerline path for them to program into their
machine.

--
Sincerely,
Brad Velander

Is this generally acceptable? I want to overlap two of 0.136" holes by
about 0.024" in several places. They are plated with no electrical
function.

Thanks!

Best regards,
Spehro Pefhany

http://www.speff.com

 

[Spehro Pefhany]

Spehro,
Do you want a slot or a figure eight shape?

Figure 8. I have 16 connectors with snap-in fingers on either side
that I need to mount as close together as practical.

I always use one of either two methods for such things.
1) I use a unique hole size for one pad, 1 - 5mils, something
they cannot attempt to drill. Then do a note referencing that
drill size and a small drawing outlining the shape and dimensions
based upon the unique hole size being the center of one of your
lobes.

What's the advantage of that? To draw attention to it so that they
cannot "fix" it?

2) If it is a slot, then I usually use a mechanical layer to
draw the shape I want in the correct location and orientation.
Then reference it in your notes telling the fabricator that this
shape is desired and that it is plated. Make sure there is some
common reference between layers so that a Gerber set aligns the
detail precisely where you want it and in the correct orientation
on the PCB.
I have also give these details on multiple layers with the
lines actually including an offset for appropriate router bit
diameters that I know the fabricator has. Theses layers are then
just a router centerline path for them to program into their
machine.

Best regards,
Spehro Pefhany

 

[Roger M Unwin]

Is this generally acceptable? I want to overlap two of 0.136" holes by
about 0.024" in several places. They are plated with no electrical
function.

Hi Spehro,

Yes totally acceptable at the size in question. I would be amazed if any
manufacturer found it a problem. Only side effect of the double drill
that I can think off would be the possibility of a few broken glass
fibres protruding where the two holes intersect.

 

[Spehro Pefhany]

Hi Spehro,

Yes totally acceptable at the size in question. I would be amazed if any
manufacturer found it a problem. Only side effect of the double drill
that I can think off would be the possibility of a few broken glass
fibres protruding where the two holes intersect.

Thanks! Out it goes. ;-)



Best regards,
Spehro Pefhany

 

[Brad Velander]

Spehro,
Yes the advantage is that it is a hole they just cannot drill
if they have missed it's true function through the notes. The use
of a hole also gives you (and them) one precise location relative
to the rest of the database.
So the figure 8 takes one snap in lead from two connectors
and you just wanted them close so that they broke into each
others holes? I am now wondering what type of connector your
talking about and if maybe a short slot on the other axis would
be better (a straight edge instead of the round edge). The
connector doesn't fit over the figure eight I would guess, unless
it doesn't connect electrically to the board at least.

 

[Spehro Pefhany]

Spehro,
Yes the advantage is that it is a hole they just cannot drill
if they have missed it's true function through the notes. The use
of a hole also gives you (and them) one precise location relative
to the rest of the database.
So the figure 8 takes one snap in lead from two connectors
and you just wanted them close so that they broke into each
others holes? I am now wondering what type of connector your
talking about and if maybe a short slot on the other axis would
be better (a straight edge instead of the round edge). The
connector doesn't fit over the figure eight I would guess, unless
it doesn't connect electrically to the board at least.

It doesn't connect electrically (plastic snaps), and the legs are not
round, they are rectangular. Ideally slots would be punched, but the
volume isn't there.


Best regards,
Spehro Pefhany

 

[Brad Velander]

Spehro,
Yeah, I was suspicious that the round holes probably weren't
the optimum hole for anything that snapped in. Simply because
most snap in parts would only fully catch at the outside corners
rather than along the full length of the snap face.
Would short routed slots not be better? Slightly longer than
the length of the snap face. Then the whole face of the snap
feature can bear the loading instead of just the corners.
Typically you can get 0.032", 0.625" or 0.093" routing diameters
from most fabricators. Other sizes would not be as common, even
0.032" is not so common with a lot of them.

 

[Spehro Pefhany]

Spehro,
Yeah, I was suspicious that the round holes probably weren't
the optimum hole for anything that snapped in. Simply because
most snap in parts would only fully catch at the outside corners
rather than along the full length of the snap face.
Would short routed slots not be better? Slightly longer than
the length of the snap face. Then the whole face of the snap
feature can bear the loading instead of just the corners.
Typically you can get 0.032", 0.625" or 0.093" routing diameters
from most fabricators. Other sizes would not be as common, even
0.032" is not so common with a lot of them.

That's a very good idea. I'll ask when the final revision is done.

Thanks!


Best regards,
Spehro Pefhany