| abstract |
A method of forming interconnects on an electronic device that can be bonded to other electronic devices at low process temperatures involves attaching a first interconnect material on the electronic device to form protrusions, and then at least partially the protrusions. By attaching a second interconnect material to cover said second interconnect material, said second interconnect material having a lower flow temperature than said first interconnect material. The method is performed by flowing molten solder into a mold having a microcavity to fill the cavity and then solidify. The mold is then aligned with the silicon wafer containing the chip attached to the hot melt solder bumps, such that each microcavity of the mold is aligned with each hot melt solder bump on the chip. The aligned mold / wafer assembly then passes through a reflow furnace to move the cold melt solder in the mold cavity onto the tip of the hot melt solder bumps on the wafer. Thereby, the double metallurgical composition bumps are formed from two different solder alloys. |