Electronics Forum | Fri Aug 01 00:22:46 EDT 2008 | fowlerchang
Pattern design, paste volume,printing misalignment, place misalignment,reflow process include N2 usage. All the factor above can make tombstome happen. And the most important factor is placement misalignment except design issue. But pls check the sol
Electronics Forum | Fri Aug 01 02:10:26 EDT 2008 | fowlerchang
Pad design is not only the size of pad but also the distance between two pad. N2 will increase tombstone as we tested. 10 zones reflow oven and slow temperature ramp will reduce this defect. MustII is the equipment which is used to test the solderabi
Electronics Forum | Fri Aug 01 00:40:06 EDT 2008 | roc2x
thanks,my pad design is 24 x 23 mils and now I chnged my stencil to 24 x 20 mils ship inwrds to lower down my volume. My placement is and part data are ok. My reflow N2 is using 1000ppm, Actual is 700-800ppm I already prolonged my pre-heat butit only
Electronics Forum | Wed Jul 25 11:16:34 EDT 2007 | lloyd
Hi Folks, I hope someone can help me, Is the homeplate stencil design (for reduced solder paste) the same for preventing solder balls as it is for reducing tombstones? i.e. the reduction of solder paste under the component termination. I'm trying to
Electronics Forum | Wed Jul 25 11:55:21 EDT 2007 | ck_the_flip
Zoinks!! Doing the homeplate design on 0402 will actually make your tombstones WORSE! Think about it. Your wetting forces are now on the ENDS of the device with no solder paste toward the middle of the device to tack the part down - a gauranteed f
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 | 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 | 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 | 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
