Electronics Forum | Sat Apr 14 04:33:44 EDT 2007 | aj
the footprint is IPC standard which I have found to be less forgiving than the Jedec one for tombstoning. Enig finish - 5 thou stencil. We have historically used homeplate design but I am leaning towards 1:1. Leadfree application. aj...
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 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 | 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 | 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 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 | 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
Electronics Forum | Thu Oct 28 16:15:24 EDT 2010 | duchoang
If everything else is OK, capacitors quality could be the cause of this issue. Some caps could have been contaminated or the metal mass not even between two ends. Try different kind (manufacturer)of cap.
Electronics Forum | Sun Oct 31 11:07:09 EDT 2010 | Mark
http://www.shanelo.co.za/Article%20to%20assist%20with%20Stencil%20Design%20Guidelines.htm Stencil design
Electronics Forum | Tue Nov 30 07:53:16 EST 2010 | edmaya33
could be a printer or stencil issue. try to check your printing repeatability. Suggest to use SPI for a checking paste volume/height/area.A regular stencil cleaning may reduced your headache.
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