Maskless Fabrication for Micropad Interconnection using Electroless NiB Deposition and Application to "Chemical" Flip-Chip Bonding

Deposition behavior of localized electroless NiB deposition for pad-to-pad connection was investigated. Localized deposition occurred mainly on the area between facing pads, and anisotropic deposition toward each facing pad was obtained. Thus, this connection, "preferential bridge connection", is no need of photolithographic technique. These results indicated that this process is one of the maskless fabrication processes. Moreover, chemical flip-chip bonding containing preferential bridge interconnection was demonstrated. The chip-to-substrate interconnection with 30 micrometer pitch was successfully achieved.