Electronics Forum | Thu Oct 14 04:12:32 EDT 1999 | Paul Gerits
Hi Jim, I'm a Technical consultant/Application specialist at Philips EMT. Tombstoning is a well know problem with Nitrogen ovens. Proberly there has been a change in your Nitrogen flow or in the nitrogen it self. To see if there was a change run a
Electronics Forum | Tue Feb 23 09:09:34 EST 1999 | Steve Schrader
| What to look for that causes tombstoning and the corective action. | Check your land-patterns. If they do not meet IPC standards, change your CAD libraries to IPC (or some other industry accepted standards such as SMTPLUS). If you have "home-gr
Electronics Forum | Mon Dec 10 13:56:51 EST 2001 | slthomas
1) The additional activity of the OA flux probably took care of the oxydation. How do you plan on taking care of the presence of conductive and corrosive residues from it now, though? You're not supposed to wash those parts with water. 2) The tomb
Electronics Forum | Thu Oct 31 16:13:46 EST 2002 | babe
If your processing with Nitrogen, tombstoning can be caused by your cooling rate. Go thru the solid/liquid phase of the solder slower..iN other words as you transition into or out of the liquidus pahse if 63/37 alloy 183C, ensure that your Delta are
Electronics Forum | Thu Mar 13 15:22:47 EST 2003 | ruggi
Ditto on the profile/reflow oven...a couple years ago, we had a huge increase in the number of tombstones found post-reflow. Profiling the oven showed a decent curve with some innocuous minor deviations, and further investigation of the oven found 2
Electronics Forum | Thu Jul 07 15:32:37 EDT 2005 | saragorcos
Hi Lloyd, Have you done any ionic analysis to find out what the flux residue is composed of? If you can eliminate the source residue, then your problem obviously should go away. Though tombstoning isn't known to be much of a functional problem it i
Electronics Forum | Mon Apr 16 09:13:16 EDT 2007 | pjc
Tombstone head and a graveyard mind. I would not recommend 1:1 due to solderpaste beed out opportunities. Have you tried the inverted home-plate? Here are some good links on tombstoning and how to eliminate it: http://www.aimsolder.com/technical_ar
Electronics Forum | Thu Apr 10 07:47:47 EDT 2008 | ck_the_flip
Stencil design and pad layout are key. Too far apart - bad. If your pad geometry is correct, try the inverted home plate. That has worked well for me in the past. That, coupled with a 5-mil stencil. With regard to solder paste, some manufacturer
Electronics Forum | Mon Nov 21 10:51:12 EST 2011 | scottp
I've never seen a good article with a definitive explanation - just speculation that the increased wetting forces due to nitrogen result in increased tombstones. My own experience is that nitrogen is a very minor contributor to tombstones and can pr
Electronics Forum | Thu May 10 22:16:51 EDT 2012 | davef
It's bad practice to remix used solder paste with new solder paste in the jar. Further, some would argue that it's bad practice to reuse solder paste period. If economics force you to reuse solder paste, store it for reuse in an empty jar. When rea
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