Hello,
I face a regular phenomenon every time I do my own reflow. It is not a critical problem, but nevertheless it is a hassle and annoying. I’d like to ask you guys if somebody knows the reason and maybe if it can be remedied by myself.
I have DIY reflow process based on a controller and a miniature oven. The basic description of the problem is, during reflow, solder gets pushed out of the pads and it gathers in small balls on the sides of components. It doesn’t happen on every component, but very often, and it happens irrespective of the type and footprint. It happens with capacitors, resistors, and even ICs, regardless of shape and size. These solder balls just sit in the flux residue after reflow. I fear these might get loose and create shorts or shorten leakage paths, so I always remove them.
I have attached a picture for demonstration. (Yeah, I know the footprint of the crystal on this specific board is wrong, please disregard that – the phenomenon happens for other parts too.)
Naively, I guess this might be a problem of either the solder amount (stencil thickness?) or a mismatch between the type of solder used and the reflow profile, but either way, I have no clue which one it is or how to proceed. Though I guess if it were a problem of the stencil then everybody else ordering from redacted-well-known-chinese-pool-service would have this problem too. Or maybe something completely different?
As I said, I’ve been dealing with this problem by simply manually removing / cleaning each ball after reflow. Tbh not a big deal, but there is always a risk of missing a few, and it is kind of a hassle. I appreciate any help in finding a “cure”.

Thanks