Printed Circuit Boards - Drill before or after etching...?

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  Recently, I laid out and etched a printed-circuit board for a
project I'm working on.  When I got to drilling holes for the
components, however, some of the pads peeled off the laminate.

  Which got me to wondering if it would be beneficial to drill small
pilot holes for the components *before* I etch the board, and widen
them after etching.

   I'd be interested in hearing your opinions on the matter - do you
drill before you etch, or after?  If after, how do you keep the traces
from de-laminating?

Re: Printed Circuit Boards - Drill before or after etching...?

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After.

Try making the annulus around the hole wider. The default footprint may
be fine for a manufactured board but a wider one has more adhesive
holding it in place. Also, if you can, make your mask with "holes for
the holes" so that most (all?) of the drilling is just in the board
material and not the pad. Finally, it may be time for a new drill bit,
one that's sharp enough to cut with minimal tearing/drag.

--
Rich Webb     Norfolk, VA

Re: Printed Circuit Boards - Drill before or after etching...?
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  Something is wrong if you're having this issue.

  Could be bad drill bits or, if your problem is with the
underside of the board doing this? If so then put the board
on a drilling board, piece of wood etc..

  Jamie



Re: Printed Circuit Boards - Drill before or after etching...?
On Sun, 10 Apr 2011 13:54:52 -0400, Jamie

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  I only had an issue with three pads - two were stand-alone, with no
traces connecting them... while the third had a trace on it.

   Perhaps my drill bit was too large...?  I was using a size that fit
the holes of a manufactured prototyping board, so perhaps I should try
a smaller bit.  (The bit was brand-new, so sharpness shouldn't have
been a factor...)

Re: Printed Circuit Boards - Drill before or after etching...?

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 Drill speed too slow?

--
Boris

Re: Printed Circuit Boards - Drill before or after etching...?

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In my experience the standard pads in PCB-software are dimensioned for
"professional" manufactured, doublesided boards with inside metalized holes.
For my singlesided prototype boards I use to make the pads at least 1.4mm.
More often I make them 1.6mm. I set the drill width to 0,8mm and drill the
all the holes after etching. When a 0.8mm hole is too small I drill it once
more using a 0.9mm up to a 1.5mm drill depending on the dimension required.

petrus bitbyter



Re: Printed Circuit Boards - Drill before or after etching...?

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The only time I had problems with circuit board was really cheap board (I
can't remember what it was, brown and cracked really easy) in the early
seventies.  Phenolic board it was.

I've never had problems drilling home made boards after they've been
etched, once I stopped using that junk board.  There have been times when
I've had pads come off because I was changing components and it couldn't
live up to the reheating, but that's a different issue completely.

I recall some articles about making circuit boards did say to drill first,
but I also seem to recall that was more a layout issue, make sure you have
the holes in the right place, then add the resist.

If the pads are too small compared to the drill bit (or the drill bit too
large compared to the pad) there likely will be an issue.

   Michael


Re: Printed Circuit Boards - Drill before or after etching...?

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I think Petrus nailed the issue, too many people so single sided artwork
with PTH design rules, pads are way too small, tracks too thin, and they
look terrible.

Home made boards need to be chunky, your etchant will last longer too.  

Grant.

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