Electronics Forum | Thu May 29 14:35:37 EDT 2008 | rdmundo
Gents, We've been using a round 1:1 aperture for a 5 mils thickness on our stencil design on 0402 and recently, IPC guidelines recommend oblong, homeplate or reverse homeplate. I believed the PCB pad for 0402's area within the recommended size/dimen
Electronics Forum | Thu May 29 17:19:51 EDT 2008 | dyoungquist
On 0402s we use 20x25 mil pads with a 15 mil gap between the pads on the pcb with ENIG finish, 5 mil stencil with a 1:1 aperture (20x25 mil) and SAC305 lead free solder paste. We very rarely see any tombstoning on 0402s using this setup.
Electronics Forum | Tue Feb 04 17:24:07 EST 2003 | jonfox
we have some pretty tight 0402 placements and our best fix was to reduce the pad (vertically speaking) from .030x.022 to .020x.022. Fewer tombstones and the paste flows out to the edge of the pads nicely. Only difference is that we have a 6mil sten
Electronics Forum | Wed Feb 05 14:20:45 EST 2003 | Stephen
One thing that worked for me was simply rounding off the pads, making square pads into circlesfor the stencil. It worked but did seem a little strange turning squares into circles for 0603's and 0402's and turning cirlces for BGA's into squares, (bu
Electronics Forum | Tue Feb 04 09:03:45 EST 2003 | Russ Roberts
Greetings, I am pretty new to SMT production, and have learned much from this forum. I am getting ready to build a CCA with many 0402 parts that are really close together. I consider these fine pitch. The board also has two QFPS, so my stencil design
Electronics Forum | Wed Feb 05 21:24:35 EST 2003 | davef
Stephen's correct. Radiased outer corners on 0402 pads really do seem to improve things. We aim to try "squared-up semicircles".
Electronics Forum | Wed Feb 05 10:23:26 EST 2003 | russ
Are these the only packages that you could come up with Dave? What about all the rest? You're something else. Thanks for doing my work for me! Russ
Electronics Forum | Wed Feb 05 13:56:40 EST 2003 | davef
I figure if you need the rest, you don't need these. These strips are from some laser cutting tool fabricator. They give them to their customers [laser cut stencil fabricators] so the customer can do a good job. Yall have a nice day now, y'hear?
Electronics Forum | Tue Feb 04 22:28:16 EST 2003 | davef
You could reduce the paste by about 70%. Solder balling and tombstoning will be the issues to fight. The drivers to these don't change with the component size. Use the fine SMTnet Archives for background. Aperture Size and Thickness of Solder Pas
Electronics Forum | Tue Apr 01 11:18:47 EST 2003 | cyber_wolf
Is anyone out there successfully screen-printing SMD adhesive on an 0402 layout? We have successfully done 0603 and larger, but the deposition consistency on the 0402's is just not there. We don't always get enough epoxy on the board. We have tried a
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