Patent ID: 8496159

Claim:
A method comprising: providing a substrate in the form of a round wafer having a plurality of electrically conductive contact pads; mounting the round wafer to a carrier and positioning a pair of protective elements in adjoining relation to the wafer, each of the protective elements having a semicircular opening, the diameters of the semicircular openings matching the diameter of the wafer; providing a layer of photoresist on the substrate; patterning the layer of photoresist such that a plurality of channels are formed over the contact pads, each of the channels having substantially the same height; depositing a layer of metal over the contact pads; passing an injection molded solder fill head containing molten solder over the channels while the substrate is in a low oxygen environment, causing the fill head to engage the layer of photoresist and move translationally with respect to the wafer and the carrier; injecting molten solder containing no flux into the channels from the fill head; allowing said solder to solidify, whereby said solder adheres to the metal and forms bumps of substantially the same height; and removing the layer of photoresist.