Bottom side bridging

We are having a bridging problem with SOIC 14,16 and 20 pin devices during flow solder of the bottom side of our boards. This bridging occurs about half way up the lead between the board and the body of the IC. The chip parts are no problem. The flow solder unit is a Techincal Devices MP16.The chip parts are no problem and our setup is not unusual. FR4,63/37,dancer+laminar wave,no clean and no nitrogen. Any suggestions will be appreciated

reply »