Martin,
Unless you use a component designed for press fit application,
which utilizes a compliant section in the pin, you'll be asking
for more trouble than it's worth. Another engineer I work with,
was forced into a situation like this with screw machined round
pins, and went through all manner of grief getting holes made
consistently enough to grip yet not exclude the entry of a
non compliant pin. And she was dealing with loose pins, free
of any true position variations of a multi leaded component. She
actually had some holes on the same board, have pins fall into
them, and others in the same pattern, need an arbor press and
some get mashed by said press because they wouldn't go in at all.
I'd try to talk your engineer out of this idea.
Leonard F. Bendiksen (717)5923410 [log in to unmask]
AMP Incorporated Harrisburg, PA USA
Americas Regional Lab
> From [log in to unmask] Fri Oct 9 15:29:54 1998
> X-Sender: [log in to unmask]
> Mime-Version: 1.0
> Content-Transfer-Encoding: quoted-printable
> Date: Fri, 9 Oct 1998 12:20:29 -0700
> From: Martin <[log in to unmask]>
> Subject: [DC] Tight fit.
> To: [log in to unmask]
>
> The Lead engineer here has asked me to reduce the hole sizes for a few
> components on our through hole designs. The component leads in
question have rectangular cross sections, and he has reasoned that if
the hole is a bit small we will get a "pressure fit". These
components have been known to "float", but up till now we just lived
with it. I should mention that we switched to new assemblers who use
hand loading instead of auto insertion for their through hole jobs.
> So my question is (were you beginning to doubt I had one?)
how small should I go so as to not break the fingers of the
assemblers, but still getting the "pressure fit" he wants? 0.001" of
overlap? 0.003" of overlap? .005" of overlap? If the holes vary by
+/- .003" and the leads by oh, I don't know, +/- .002"??then could I
expect nasty anonymous letters from disgruntled assemblers?
>
> Oh yea, 2oz copper on a .093" 2 sided board, and a 1oz copper on a
.062" 2 > sided board. It seems to me that I should be fine with a
close fit, but with no overlap. Any books or articles cover this
kind of a situation? Is the lead engineer off his rocker? (not
that I would tell him, if he was ;)
> Thanks,
> M.
> -------------------
> Martin Spizman
> MEYER SOUND LABS
> (510) 486-1166
> [log in to unmask]
>
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