Abstract: The present general inventive concept includes a wave soldering apparatus, a soldering method using the wave soldering apparatus, and a method of forming a solder bump for a flip chip. The wave soldering apparatus includes a solder bath containing a molten solder. A nozzle is arranged in the solder bath so as to upwardly spout the molten solder toward a bottom surface of a substrate that passes an upper portion of the solder bath. A liquid that is separated from the molten solder is contained in a downstream area of the solder bath, and buoyancy is applied to the molten solder, which is adhered to the substrate, by the liquid. Since the amount of the molten solder adhered to the substrate is increased by the buoyancy, it is possible to form the solder bump to have a height sufficient to use it as a flip chip.