Hi all:

IPC-A-610 defined acceptable condition of solder balls is that " Solder balls are entrapped, encapsulated or attached (e.g., in no-clean residue, with conformal coating, soldered to a metal surface, embedded in the solder mask or under a component)".
But it seems we cannot be avoid that small balls (screen size in solder paste) have splattered around the connection during the reflow process, and sometimes the small balls are not entrapped, encapsulated or attached, only have a little flux residue on the bottom of solder balls. 
Can this small balls be acceptable? I remember in old version of IPC-A-610, it defined that the size of balls cannot larger than 0.13mm, why IPC have removed the size condition?


 
Best regards

Deng