Steve,  look at www.amp.com/products/technology/articles/dd66c.stm
Jim Marsico

        -----Original Message-----
        From:   Stephen R. Gregory [SMTP:[log in to unmask]]
        Sent:   Thursday, November 11, 1999 2:52 PM
        To:     [log in to unmask]
        Subject:        [TN] Intrusive Reflow

        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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