We have a QFP-308 (0.20" pitch)on a board and we have a lot of opens after reflow. We checked our profil by installing thermocouples on the pads of the component and everythings seems OK. We checked the coplanarity of the leads and it seems OK too. We noticed that the pads width are at the edge of acceptability (0.010" according to IPC-SM-782) and the board as a poor HASL.Pads are not all at the same height.Also I have solder mask between the pads.
Those things migth be the cause of the problem or maybe not. Does anybody experienced the same problem?