Pad lifting and crack formation at the surface of solder fillets on plated through-hole joints were issues in the days when boards were processed at ‘solder cutting solder’ lines, common in the 1980s. The use of lead-free solder alloys has brought about a recurrence of this crack formation, called fillet-tearing. There appears to be no cure this time; changing process parameters hardly provides any improvement.
This attached document discusses lead-free soldering and the issues of lifting of pad, fillet and fillet tearing.