When the solder process is converted to lead-free often one find some or more joints that does not give a complete hole-fill. In the past when these boards were soldered with the common tin-lead alloys this seems never to be such a serious problem. Only in case of a bad process setting, e.g. lack of flux, these problems could occasionally occur. Now with lead-free solder these problems seems to be part of the process, since they can not be reduced even with optimal settings. In fact that is often exactly the case as will be explained.
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