Patent ID: 8371498

Claim:
A method for manufacturing a printed wiring board, the method comprising: forming a solder resist layer having a small-diameter aperture and a large-diameter aperture, each aperture exposing a respective joint pad; mounting a metal ball having a first diameter in said small-diameter aperture by using a mask for small diameter metal balls, which comprises a small-diameter aperture area that corresponds to the small-diameter aperture on the solder resist layer; mounting a metal ball having a second diameter larger than the first diameter in said large-diameter aperture by using a mask for large diameter metal balls, which comprises a large-diameter aperture area that corresponds to the large-diameter aperture on the solder resist layer, wherein the mask for large diameter metal balls is a different mask from the mask for small diameter metal balls; forming a small-diameter bump from the metal ball having a first diameter and a large-diameter bump 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, and selecting a size for each of the small diameter aperture, the metal ball having a first diameter, the large diameter aperture, and the metal ball having a second diameter, these sizes being selected to provide the small-diameter bump and the large-diameter bump having a same height; wherein said mounting a metal ball having a first diameter comprises: providing at least one mount cylinder, the at least one mount cylinder having a suction area for removing air from an interior of the at least one mount cylinder, and an aperture area for intaking air into the interior of the at least one mount cylinder in response to said suction area removing air, aggregating a plurality of metal balls having the first diameter on the mask for small diameter metal balls by: positioning said aperture area of the at least one mount cylinder above an upper side of the mask for small diameter metal balls, and sucking air through the suction area of said at least one mount cylinder such that the plurality of metal balls having the first diameter are aggregated under the at least one mount cylinder by intake air through the aperture, without removing any of the plurality of metal balls aggregated from the at least one mount cylinder through the suction area; and dropping the metal ball having a first diameter into the small-diameter aperture on the solder resist layer through the small-diameter aperture area of the mask for small diameter metal balls by moving the at least one mount cylinder along the mask for small diameter metal balls thereby moving plurality of metal balls aggregated on the mask.