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
Electronics Forum | Thu Apr 12 10:01:43 EDT 2007 | realchunks
Hi aj, Pete is right, there are several variables that can affect your quality when it comes to stencil design. A good idea is to have a stencil made with various designs incorporated into it. A lot of engineers like the reverse homeplate design.
Electronics Forum | Tue Dec 26 12:35:09 EST 2000 | Dave F
Your English is fine. Your assessment that corrosion on a portion of the metalization on the end of a component is causing the tombstoning is reasonable. We've seen that before. Corroded components received from a supplier is not acceptable as an
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 | Wed Jan 10 20:06:43 EST 2007 | SSS
I've been assembling thousands of boards for dozens of customers over the past 5 years with 0402 chip components. 85% can happen very easily even with newer equipment. Defect challanges with 0402 packages is almost always tombstoning. Capacitors abou
Electronics Forum | Thu Oct 28 09:52:39 EDT 2010 | dyoungquist
Try rotating your board 90 degrees when running it through your oven. Will probably solve the tombstoning issue on that cap but might cause tombstoning elsewhere.
Electronics Forum | Thu Oct 28 10:06:12 EDT 2010 | d0min0
We saw this idea in older posts, but - we don't want tombstone elsewhere :) - rotating the boards before oven is complicated, so it could give more problems than the tombstoneing :) the issue is not 100%, it is 10 to 50 boards with component up per 3
Electronics Forum | Fri Oct 29 07:10:40 EDT 2010 | scottp
I agree with DucHoang. If your board and reflow profile have not changed then I would suspect incoming parts. We've seen tombstones when a chip supplier had plating problems.
Electronics Forum | Thu Nov 04 04:27:46 EDT 2010 | d0min0
thanks for all the feedback... we also checked, just in case : - bake the components (no visible improvement) - bake the pcb (50% less tombstone components) - finally we changed LF paste to completely different manufacturer - and booom 0 (zero) tombs
Electronics Forum | Thu Oct 28 08:28:33 EDT 2010 | d0min0
Hi, previous topics found closed so I couldn't continue on them, but wanted to ask maybe something that we don't already know paste shape and placement ok, reflow 12 zones profile looks ok (same since 2 yrs), component placement ok, one reference i
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