Tracy,
I'm sure you'll get a plethora of email on this subject.
However you didn't state if your boards were electroless or additive plated.
I have found:
Most important is the ability of the supplier to drill economically i.e.
stack multiple boards when drilling.
The issue with this is drill wander, having a target pad large enough hit
repeatedly with minimum breakout if allowed.
The Aspect ratio of the "hole to board thickness" is next most important due
to the ability of the supplier to plate the barrel of the hole.
With high aspect ratio holes the barrel can get unevenly plated similar to
the shape of an hour glass. This leads to barrel breakage.
I've used holes that were .014" drilled, finished to .010" in a .022" land
that was produced successfully and economically in .040" to .062" thick
boards.
I've found that suppliers prefer a minimum of .004" per side metal land for
drilling. Talk with your board supplier and ask what their process is.
Explain what your design intent is. They'll give you their best response for
design rules that will meet your needs and their process.
Good luck!
Mike



-----Original Message-----
From: Tracy Black [mailto:[log in to unmask]]
Sent: Tuesday, April 06, 1999 8:33 AM
To: [log in to unmask]
Subject: [TN] Coax to P.C. board mounting


Hi all you valuable TechNet'ters:

My company makes very small coax type push-on connectors for P. C. board
applications among others.  I would like to know if there is a standard
size pad for a given through via size?  The next question would be what
would happen if, for electrical reasons I could not comply with the
recommendation?  My via size is about .015" and I am designing a solder
application for a customer so that they can absolutely minimize the
spacing between boards.  I have only been in this business a few years
so I am trying to learn the little tricks to the trade or maybe it's
better stated as the exceptions to the rule..

T. Black

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