Hey Techhies,
Is there any body out there using pin-in-paste (intrusive reflow, whatever
you want to call it) on parts with a lead pitch of 50 mils?  I have a 38
pin and 30 pin 50 mil pitch through hole right angle header I need to
solder on a double reflow board.  I can't slelective wave solder because
they sit on right angles to one another (I'm sure one would have solder
bridges), I don't want to hand solder because of the added cost, and I
prefer not to use a fountain solder (we've had bridging and insufficient
hole fill fountain soldering other 50 mil connectors).  The pth diameter is
about 0.022".  The leads are 0.015" square.  There is minimal lead
protrusion through the board, about 0.025".  We've done some experimental
p-i-p boards with a 6 mil stencil but only acheive acceptable (75%) hole
fill on about 50% of the connections.  We also tried 0.025" holes with
worse results.  I have 20 mil QFP's on the same side as the connectors so
I'm hesitant to go with a thicker stencil.  Next step will be to try a step
down stencil.

If you have any experience or recommendations on stencil aperture
configurations, stencil technology, paste types, etc., etc, I'm all ears.

Jim Gryga

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