Electronics Forum | Tue Mar 11 10:13:15 EST 2003 | genny
Some people have said that for smaller components like 0402, a 2% silver paste (62/36/2)has helped reduce the tombstones. The reasoning is that this paste has a longer plastic zone compared to a true eutectic solder, and if there is any uneven heati
Electronics Forum | Tue Mar 11 14:19:24 EST 2003 | Chris Lampron
Good Afternoon, We have found that the occurance of tombstones is usually related to other parameters. Board design, placement accuracy, paste tack time and thermal profile are the most common. We do use a 2% silver paste to process 0201 components
Electronics Forum | Thu Mar 27 14:38:44 EST 2003 | MA/NY DDave
Hi kenlchin, Yes, This all helps with these little components that can be affected by the forces created during soldering more so, than their own stabilizing weight. On this tread which started with a composition only proposition, we have seen tha
Electronics Forum | Fri Mar 28 22:01:00 EST 2003 | MA/NY DDave
Hi Yes I agree, yet this subject is about Tombstoning and oven profile or even oven working correctly across the entire product is a sub-set of how one gets those little chip babies to sit and stay where they belong. Flat and Heeling like their mast
Electronics Forum | Fri Apr 04 05:02:08 EST 2003 | alexyalung
Hi All, The best solution we made on our tombstone defects is component Z dimension set at pick and place machine. Usually for 0402 components Z height is pre-set by the machine at 0.5 mm, by reducing it to 0.35mm we have solve our tombstone problem
Electronics Forum | Tue Mar 11 11:22:38 EST 2003 | slthomas
Is a water-soluble flux based paste an option for the bottom side? Then you could wash the residues from the board before wave. That's the only way we've tried that process. The difficulty we had was with some disturbed joints, apparently from s
Electronics Forum | Wed Mar 12 08:03:30 EST 2003 | Surachai
Hi all Pls. help advise. Our board use RMA solder paste (Pb-free Sn96.5/Ag3.0/Cu0.5). Can we use No-clean paste flux (Delta 670S1) in rework process? If it can not be used, why?. Thanks very much for your advice. Surachai
Electronics Forum | Wed Mar 12 09:23:56 EST 2003 | MA/NY DDave
Hi I don't see in your note any particular reasons why you couldn't. If it solders well and passes what ever specifications you are using than everything is OK. If your repair faces some soldering or rework challenges where a more agressive flux is
Electronics Forum | Wed Mar 12 10:25:29 EST 2003 | davef
J-STD-001C, 7.2.1 Flux Application says words to the effect of: When an external flux is used in conjunction with flux cored solders, the fluxes shall be compatible. Regardless of whether these are or not flux cored solders, this begs the question:
Electronics Forum | Thu Mar 20 14:17:39 EST 2003 | MA/NY DDave
Hi I don't think I will enter this too much except for one of your questions. YES multiple reflows affect reliability. Heck most everything affects reliability. Aggressive Heat cycles or Heat always affects the final MTBF reliability number. The
