Electronics Forum | Tue Feb 09 16:53:06 EST 2021 | SMTA-64387083
The size of the pad changes among the two. A solder mask defined pad will always be larger than a copper defined by your mask expansion setting. This will affect paste volume, if your standard paste aperture is designed for copper defined pads you m
Electronics Forum | Thu Sep 07 10:45:46 EDT 2006 | vicknesh28
Yes solder is reflowing on the pad but doesnt wick up the lead. Solder paste is sufficient. It just forms a saddle like appearance beneath the failing lead. The failed lead doesnt get reflowed at all. What puzzles me is how can hundreds of leads wet
Electronics Forum | Mon Aug 27 10:58:44 EDT 2001 | Ryan Jennens
Steve- We had the same trouble with 0805 Panasonic film caps. We had some tombstoning and open solder joints (non-wetting). We found two problems...like you, we changed our pad design to meet their recommendation. Also, they were able to suppl
Electronics Forum | Fri May 26 04:58:19 EDT 2023 | auriga2001
I agree with the two other replies. Left alone, it is a defect. If it's just excess adhesive or coating, you can use IPC-7711/7721 'Rework, Modification and Repair of Electronic Assemblies' for guidance on removing. Section 2.3.1 explains how to te
Electronics Forum | Fri Apr 29 14:16:16 EDT 2011 | ppcbs
Below is the long explanation. This defect is most commonly found with BGA components, but can arrise with all components. I see it happening more now with lead free boards that are being assembled with a no clean flux. Best short term remedy is t
Electronics Forum | Fri Aug 04 06:43:40 EDT 2017 | kubabel
Dear all, I´d like to ask You, if somebody faced similar situation like we are facing in our plant right now. We have wetting problems with some of our products. During SEM/EDX we found on non-wetted parts residues of Mineral oil - white - heavy. Do
Electronics Forum | Wed Oct 27 19:50:59 EDT 1999 | chris
Hi What is the possible cause of non-wetting of solder paste to the gold land pad. What we observed in the surface of the non-wet pad is an organic FM, and using FTIR we found out that it is a flux. It is possible that the cause of non-wetting is
Electronics Forum | Thu Oct 28 09:25:35 EDT 1999 | Dave F
Chris: Typical non-wetting causes are: * Poorly controlled soldering process * Incorrect material * Surface contamination * Insufficient preheat * Misapplied solder mask * Shadowing Without intending to insult you, all of the causes of non-w
Electronics Forum | Wed Mar 30 01:01:10 EST 2005 | vicknesh28
All, Has there been any finding from the component point of view in terms of non wets after reflow and if yes, can anyone share what was improved on the component to reduce the non wet defective levels. What would be the contribution from the compon
Electronics Forum | Fri Nov 05 10:01:04 EST 1999 | Dave F
Chris: You can have more than "one question!!!" Anyhow, yes crappy solder paste can cause non-wetting, but before you go there understand why the paste is wetting some surfaces, but not others. Ta Dave F
