Patent ID: 8820612

Claim:
A method comprising: positioning a round wafer on a carrier such that a top surface of the wafer is coplanar with a top surface of the carrier; positioning wafer protectors in adjoining relation to the wafer, the wafer protectors comprising the top surface of the carrier, the wafer protectors further comprising a pair of protective elements, each protective element having a semicircular opening defined by semicircular walls, wherein the step of positioning the wafer protectors includes positioning the protective elements such that the semicircular walls adjoin the wafer and form a circular opening having a diameter matching the diameter of the wafer; applying a dry film of photoresist to the top surface of the wafer and an adjoining top surface of the carrier; patterning the photoresist, thereby creating channels in the photoresist; forming metal pillars on the top surface of the wafer; passing a fill head containing molten, flux-free solder over the wafer and carrier while injecting the molten, flux-free solder into the channels such that the solder contacts the metal pillars and completely fills the channels; solidifying the solder in the channels, forming solder bumps of uniform height; removing the dry film of photoresist, and detaching the wafer from the carrier.