A properly filled 40 mil hole contains more paste than a 70 mil stencil aperture, so please don't forget to pay attention on how to get the paste INTO the holes  Experiment with things like squegee speed, pressure, and solderpaste rheology.

Daan Terstegge
Unclassified

>>> "Stephen R. Gregory" <[log in to unmask]> 11/11 8:51 pm >>>
Hi ya'll!

I'm getting ready to do some intrusive reflow on this board we got
here...(this is my first time! I'm s-o-o-o nervous...not really...well, maybe
a little...hehehe) Anyways,
the parts are going to be 2, 20-pin SIP sockets. The board is .063" thick,
the holes
are spaced .100" apart, and the hole diameter is .040". I'm trying to decide
how big I should make my apertures.

I've looked at all the archive postings (there are a 168 of them on intrusive
reflow) to see if anybody posted any recommended stencil thicknesses, and/or
aperture sizes,
but there was none. I looked on the web, but couldn't find any real
guidelines either...
(hmmmm, something I couldn't find...now THAT's a change!)

I need to keep my stencil thickness at 6-mils, 'cause I've got some 20-mil
pitch stuff on the same side. I was thinking of doing .060-.070" diameter
circles over the holes...
does that sound okie-dokie?

I did a little test with the SIP socket and a syringe full of solder paste. I
drew a bead of paste (about .030" dia.) down the row of holes and dropped the
connector in, then reflowed it. Then I got my dremel tool out and did me a
rough cross section to check the barrel fill. It actually wasn't too
bad...there were about 2-3 holes that were a little shy volume-wise but that
was because (I think) the solder wicked over to the holes next to it because
of the continuous bead of paste I had laid down. That shoudn't happen when I
have individual deposits of paste for each hole.

So how big should I make my openings? Did I guess right at .060-.070"?

-Steve Gregory-

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