Defect : Insufficient hole fill Process/machine infomation :  Board type - Double sided  Solderability protection - OSP  Flux carrier - Water  Preheat type - Infrared  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. Dwell time too short. Topside board temp too low. Topside board temp too high for flux, causing flux to burn off before board reaches waves. Flux not active enough or solids percentage too low. Solder temperature too low Not enough flux. Wave height too low on one or both waves.   Board and design solutions Plated through hole tied to power/ground plane without thermal relief.