Defect : Icicles 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. Solder temperature too low. The use of nitrogen will prevent icicles. Not enough flux.   Board and design solutions Plated through hole tied to power/ground plane without thermal relief.