Patent Number: 8,820,612

Title: Injection molded solder process for forming solder bumps on substrates

Abstract: Solder bumps of uniform height are provided on a substrate through the use of injection molded solder. Copper pillars or ball limiting metallurgy are formed over I/O pads within the channels of a patterned layer of photoresist. Solder is injected over the pillars or BLM, filling the channels. The solder, which does not contain flux, is allowed to solidify. It forms a plurality of solder structures (bumps) of equal heights. Solder injection and solidification are preferably carried out in a nitrogen environment or a forming gas environment. Molten solder can be injected in channels formed in round wafers without spillage using a carrier assembly that accommodates such wafers and a fill head.

Inventors: Feger; Claudius (Poughkeepsie, NY), McLeod; Mark H. (Poughkeepsie, NY), Nah; Jae-Woong (New York, NY), Perfecto; Eric D. (Poughkeepsie, NY)

Assignee: International Business Machines Corporation

International Classification: B23K 3/00 (20060101); B23K 3/06 (20060101)

Expiration Date: 9/02/12018