A packaging method for assembling a screw to a printed circuit board (PCB) includes the steps of: providing a screw having a head, a threaded shank, and a ferrule enclosing the threaded shank; mounting a stop ring on the threaded shank to maintain a predetermined height from top of the head to bottom of the ferrule; using a tool to fetch the screw and align the threaded shank with one through hole provided on the PCB; releasing the screw from the tool for a flange of the ferrule to extend into the through hole on the PCB; heating to melt a solder layer atop of the PCB, so that the ferrule is fixedly held to the PCB when the molten solder layer is cooled and hardened again; and removing the stop ring so that the threaded shank is retracted into the ferrule.