Chingho Philip Chan and Guowei David Xiao, both of Kowloon, Hong Kong, have developed under-bump metallization layers and electroplated solder bumping technology for flip-chip.

        According to the U.S. Patent & Trademark Office, the invention relates to a "series of improved processes and methods to manufacture solder bumps on the wafer which shrink the space among solder bumps and reduce the cost of manufacturing. A design method and a relevant manufacturing process are introduced to form an organic material or metal material layer, which is called a Bump-Reflow-Control Layer. The pad patterns can be defined by this method. A mechanical part is designed with a hermetic cover to improve the photoresist process. The series of photolithography process including the designing method of related photolithography mask is introduced to achieve the high quality and thick photoresist."