Electronics Forum | Wed Mar 15 22:08:20 EST 2006 | davef
Brad We agree with Rob. Even if the fab marks the fids [on both sides] to reduce component attrition, you'd be surprised in the amount of paste that 'disappears' on x-out boards. Do the numbers [follow the money].
Electronics Forum | Wed Mar 15 08:52:46 EST 2006 | russ
Best way to judge how good a profile is by measuring it. It is not real accurate to determine by the amount of residue left. You should be able to tell if the lead is bent causing the open.
Electronics Forum | Wed Mar 15 09:01:11 EST 2006 | Vick
The lead was inspected for coplanarity and it's within the specification it's designed for and doesn't show any variation in terms of height as compared to it's adjacent lead that has good wetting
Electronics Forum | Wed Mar 15 09:21:40 EST 2006 | vicknesh28
Thanks for the input. Just one question. Is what i am seeing normal? I am refering to the flux being between the lead and molten paste after the reflow process. This only found on a non-wetting lead.
Electronics Forum | Wed Mar 15 11:19:43 EST 2006 | slthomas
Based on that criteria I would also guess profile but as has been stated, you don't really know w/o profiling.
Electronics Forum | Wed Mar 15 11:27:05 EST 2006 | stepheniii
By any chance is it eutectic paste and pallidium leads? Also how tight are you checking coplanarity? At least with the MPA-G3 you can check so tight that any IC will fail in the real world. Or you can check so loose that you might as well not check.
Electronics Forum | Wed Mar 15 13:25:25 EST 2006 | russ
Your profile is definitely off. It could be bad leads but it sounds like your max temp is too low and the TAL is too short. By how much? Don't know.
Electronics Forum | Thu Mar 16 04:35:49 EST 2006 | vicknesh28
Paste is eutectic and it's copper based parts. Just another observation, i notice that the "flux" between the bottom foot and solidified paste is still in gluey state. Observation on good reflowed leads showed brittle type of flux residue. Can anyone
Electronics Forum | Fri Mar 17 09:32:45 EST 2006 | vicknesh28
It's a no clean paste. Yes it's a single lead (sometimes a few at random locations) and i do notice that corner leads (or close to it) fails more.
Electronics Forum | Thu Mar 16 10:19:15 EST 2006 | slthomas
Is it possible that the other facility you were at was running a WS paste more or exclusively? We found that the nc Kester left us with a lot more sticky mess than the ws. That said, are you sure you're also getting enough exhaust airflow?
