Hi Tom,
I don't have a problem with what your predecessors did in the past. Seen
it many times so far. One suggestion I might make is to increase your
tolerance range on the .013" finished holes to be +.003/-.013 That
would allow the fabrciators to do a couple things. 1) They could plate
the vias shut, assuring them the .001 plating required; or 2) to use a
smaller drill to meet the application. Either way, it's a sure win for
you, and will make the fab house happier, especially if your boards are
very dense. But, for .062 boards, what you've used in the past still
sounds plenty reasonable to me. Heck, I've seen a .096" board with .015"
finished holes with .025" pads! Did it work? Yup, 'cuz they also spec'd
+.003/-.015" finshed tolerance. :)
Good luck.
Mitch
Sr PCB Designer
San Diego, CA
---------Included Message----------
> Date: Thu, 30 Mar 2000 09:18:52 -0500
> From: "Frayda, Tom" <[log in to unmask]>
> Reply-To: "DesignerCouncil E-Mail Forum."
<[log in to unmask]>, "Frayda, Tom" <[log in to unmask]>
> To: <[log in to unmask]>
> Subject: [DC] signal via padstacks
>
>
> I would like to take an informal survey of what folks are
commonly
> specifying for standard signal via padstacks for 0.062" thick, 1
oz copper,
> 2-4 layer boards.
>
> I am in the process of revamping our decal libraries to comply
with IPC
> Level B producibility (as much as realistically possible) and am
troubled by
> the 0.013" +/-0.003" Dia. finished hole / 0.025" Dia. pad that
was specified
> by my predecessors. This doesn't even meet Level C and I am
concerned about
> the possibility of breakout. However, to the best of my
knowledge, breakout
> with these vias has not been a problem in the past.
>
> Also, since this via is currently being used, I do not want to
increase the
> pad size, but would rather decrease the finished hole size. What
is the
> minimum finished hole size that won't drive up the cost with your
particular
> fabricator?
>
> Your comments on this would be appreciated.
>
>
> - Tom
>
>
> *******************************************
> Thomas A. Frayda, C.I.D.
> PCB Designer
> Detection Systems, Inc.
> 130 Perinton Parkway
> Fairport, NY 14450-9199
> www.detectionsys.com <http://www.detectionsys.com/>
> www.dsworld.com <http://www.dsworld.com/>
> TEL: 716-223-4060 x4365
> FAX: 716-421-4263
> E-mail: [log in to unmask]
<mailto:[log in to unmask]>
> *******************************************
>
>
---------End of Included Message----------
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