Defect : Solder balls Process/machine infomation :  Board type - Double sided  Solderability protection - OSP  Flux carrier - Water  Preheat type - Forced Convection  Process solutions Conveyor speed too slow. a. Time over preheat too long causing flux to be burned off. b. Dwell time too long causing flux to be destroyed before exiting the wave. Conveyor speed too fast. a. Time over preheat not long enough to dry flux carrier. Flux not active enough or solids percentage too low. The use of nitrogen may increase solder balls. Not enough flux. Flux carrier is not being completely dried by the preheat. Too much flux.   Board and design solutions Lead length too long. Solder mask type or curing. a. Matte finish is preferred.