Electronics Forum | Mon May 26 04:02:13 EDT 2003 | Franky
Dear sir, I think so with every idea , everyone is correct , paste , pattern of pad design ,profiling or solder mask on PCB ,and one of the cause of tombstone that I found is alignment of machine placing and solder printing , from my experience many
Electronics Forum | Fri Sep 20 17:43:03 EDT 2019 | deanm
Looks like poor wetting/solderability to me. I don’t see heel fillets on the leads where the solder balls up. The solder has to go somewhere. It won’t flow where it won’t wet. Try printing a bare board and run through reflow. If the solder balls up o
Electronics Forum | Fri May 16 15:45:00 EDT 2003 | swagner
If the only difference between the two products is the board supplier I believe thats where I would start, we had a similar problem like this two months ago and it turned out to be a faulty (thin) HASL layer which did not meet our print tolerance. T
Electronics Forum | Sat Nov 22 09:51:51 EST 2008 | realchunks
You need to take it a few steps farther. The main reason you would want to reject a certain % off print is because it made defects. So you need to see how far you can go without creating a defect and then establish that as your cut off and the need
Electronics Forum | Thu Dec 26 12:41:53 EST 2019 | emeto
We agree with your statements. 1. Having manually printed board will compromise your print and you don't know how much paste you have on each pad. 2. LEDs falling off that easily might be related to contamination, considering that your profile is not
Electronics Forum | Tue Jun 23 13:23:55 EDT 2020 | emeto
If you swear in having consistent print, I bet you it is the part. Some of these BGAs probably have missing or inconsistent balls.
Electronics Forum | Wed Mar 16 09:06:07 EST 2005 | russ
This is what I might do, I would purchase either a solder volume (preferred) or at the least a paste height measurement piece of equipmment, The most important parameters with pronting are volume and registration. You need one of these inspection
Electronics Forum | Wed Sep 22 21:23:03 EDT 1999 | se
| | I've had some trouble pasting a test board for a MicroBGA trial. Most of the paste remains in the stencil apertures. | | The stencil is 6 mil thick, laser cut and electo-polished. | | The apertures are 12 mil in diameter with 20 mil pitch. | | We
Electronics Forum | Thu Sep 23 12:47:48 EDT 1999 | Earl Moon
| | | I've had some trouble pasting a test board for a MicroBGA trial. Most of the paste remains in the stencil apertures. | | | The stencil is 6 mil thick, laser cut and electo-polished. | | | The apertures are 12 mil in diameter with 20 mil pitch.
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
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