A method for manufacturing a printed wiring board, the method including forming a solder resist layer having a small-diameter aperture and a large-diameter aperture, each aperture exposing a respective joint pad. A metal ball having a first diameter is mounted in the small-diameter aperture by using a mask for small diameter metal balls, which includes a small-diameter aperture area that corresponds to the small-diameter aperture on the solder resist layer. A metal ball having a second diameter larger than the first diameter is mounted in the large-diameter aperture by using a mask for large diameter metal balls, which includes a large-diameter aperture area that corresponds to the large-diameter aperture on the solder resist layer. A small-diameter bump is formed from the metal ball having a first diameter and a large-diameter bump is formed from the metal ball having a second diameter by heating each of the metal ball with a first diameter and the metal ball with a second diameter to at least their respective reflow temperatures.