Hi guys,
We are the PCBA manufacturer. Currently, we got a problem with flux after reflow on I/O connector. There are some tiny flux drops (max diameter is about 0.25mm, the width of pin is about 0.5mm) found on contact pin (actually we don't know whether it is flux or not). We checked part before reflow. The flux drops are transparent. We suspect that it is caused by reflow process when solder paste melts and flux from lead of connector splashes to the contact pin.
However, there are some matters which need to be considered as follows:
- We have 21 SMT lines but this problem concentrates seriously on some lines only. The other lines, they are not considerable.
- Sometimes, it doesn't happen.
- We are using Pb-free solder paste with nitrogen in Reflow.
- Reflow machines have same model but the settings for each reflow is different because our delta T is very severe and different machine has different mechanical factors (therefore, setting values for m/c are not same) but the profiles of all machines satisfy our criteria.
Pls. refer the attached photo for detail.
Have you ever gotten that case? What are your solutions for that?
Thank you very much for your advices,
All the best,
Le Ai Quoc




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