Electronics Forum | Tue May 07 10:36:38 EDT 2019 | slthomas
Probably just means you started out with an optimal profile. I suspect that not everyone does. ;) It seems like we did have some luck with profile adjustments in one instance with some QFN's with a large thermal pad. Like I said, though, the profi
Electronics Forum | Thu Feb 08 09:41:23 EST 2007 | SWAG
Check the bare board - could also be an unmasked via on the heel of the pad that is sucking solder into it.
Electronics Forum | Thu Feb 08 08:54:56 EST 2007 | jhaviland
groundplane not heating properly.. Is it a J leaded IC? sometimes these get bent slightly in the packaging and sit just far enough off the board to cause solder problems.
Electronics Forum | Tue Feb 19 11:27:25 EST 2019 | emeto
Thanks Rob, actually the thermal relieve is very poor. We did attach the thermo couples on the pad so that is checked. I will now check solderability.
Electronics Forum | Tue Feb 19 15:37:46 EST 2019 | emeto
Steve, we have great system in place to trace the paste and it's compliance. This board is actually very busy and all is soldered great besides this capacitor. I will keep investigating.
Electronics Forum | Fri Feb 17 19:23:05 EST 2023 | SMTA-64387083
Read the articles everyone else recommend. I haven't read of them but I will say this. A Solder Mask Defined pad is a copper flood that has much more thermal mass than a Non-Solder Mask Defined pad so it will heat and cool at a slower rate. I suspect
Electronics Forum | Sun Apr 11 11:39:52 EDT 2010 | manchella
When we have sent some of motherboards for reliability testing in a tird party laoratory. It is found that when Dye&Pry is done after 600 cycles of Thermal Cycling, in LGA socket only one of the corner solder joing had 100% type 3 crack. All other so
Electronics Forum | Mon May 06 11:45:32 EDT 2019 | slthomas
There are quite a few papers out there on the subject. Just enter "SMT void reduction" into google or other search engine and take your pick. That said, slow ramp rates and paste volume reduction are a good place to start. Although I haven't tried i
Electronics Forum | Thu May 30 09:33:15 EDT 2019 | emeto
Contributors in order of importance: 1. PCB design - if you have large thermal pads, a grid of via holes should be created. Components with low profile will not let the gas to escape from the joint. The only way is going down. 2. Reduce paste volum
Electronics Forum | Tue May 28 18:31:08 EDT 2019 | jlawson
Solder paste flux is main contributor, Lead termination chemical-oxide by products and PCB Plating-Chemicals. Reflow profile would have very limited if not no impact really unless is way off. Paste volume control and Stencil design plays a big part
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