Electronics Forum | Wed Nov 13 12:06:53 EST 2019 | slthomas
The answer is usually either too much paste or paste being deposited where it doesn't belong. In some instances the two are related. You don't say what kind of parts you're having problems with and that matters too. I agree with the previous poste
Electronics Forum | Tue Jul 06 10:46:12 EDT 2004 | blnorman
We have now switched to Kester EP256. During our solder paste evaluation, resistance to humidity was one of the selection criteria. We printed multiple boards, then exposed them to 85�F/65% RH. At 30 minutes, 1 hour, 2 hours, and 4 hours exposure
Electronics Forum | Sat Jul 26 07:31:14 EDT 2008 | bobwillis
We have created a new online free database on process defects at NPL which you can search. http://defectsdatabase.npl.co.uk There are many reasons for solder balling on wave and reflow and examples are provided. You could always use the database t
Electronics Forum | Thu May 03 10:14:10 EDT 2001 | davef
Now, I'm not going to talk solder balls, in a traditional sense. I have an image of bilbous, globs of excess solder near the ends of PTH leads. If that's not what you have, ignore the following [and help us understand your situation better] ... Yo
Electronics Forum | Thu May 17 08:28:14 EDT 2001 | wavemaster
I would have to agree that the leads are probably geting to hot, but there are many factors that could be the root cause. I would suggest doing a experiment with a solder sample and make 2 recipes. One with a relativly cold profile and one with a r
Electronics Forum | Tue Jul 20 02:36:03 EDT 2004 | yukim
Hi, The solder paste is SE5-M951X-9. Comparing with the previous one we used, we are having much more tombstoning problems. The reflow profile is such as: room temp to 140C: 85~95 sec 140 to 170 C: 80 sec 170 to 200 C: 20 ~ 23 sec Above 200 C: 44 ~
Electronics Forum | Tue Jul 17 15:13:53 EDT 2001 | mparker
Dave - I agree that the U shape for QFP's sounds a bit whacked, for the reasons you state. It may work OK for larger pitchs but then again there are a myriad of fixes that work before resorting to U shapes. With the U shape removing paste from under
Electronics Forum | Thu Jul 19 08:00:03 EDT 2001 | doctord
Solder balls or mid chip beads? Remember IPC classification for Class 2 allows mid chip beads encapsulated in flux. Usually on R's and C's first thing I would do is verify .006 laser stencil 10% reduction and the most critical, The paste must be on t
Electronics Forum | Wed Jun 30 10:24:27 EDT 2004 | K
We find keeping the work environment at about 22degC and humidity to about 40-50% is the best way to control the solder balls. Before we took measures we were out of control with solder balls especially in the summer months. We run aqueous solder thr
Electronics Forum | Tue May 11 15:52:03 EDT 2004 | Erhan
It's been 10 years since I started to use this editing method but never knew that it was called wendy-house style. :-) This is most probably the answer you're looking for if you're only having problems around the 1206 types. For QFPs, I used to redu
