A new flip-chip bonding technique using micromachined conductive polymer bumps

Using micromachining techniques with thick photoresists, a new conductive polymer flip-chip bonding technique that achieves both a low processing temperature and a high bumping alignment resolution has been developed in this work, By the use of UV-based photolithography with thick photoresists, molds for the hip-chip bumps have been patterned, filled with conductive polymers, and then removed, leaving molded conductive polymer bumps. After flip-chip bonding with the bumps, the contact resistances measured for 25 mu m-high bumps with 300 mu m x 300 mu m area and 900 mu m x 400 mu m area were 35 m Omega and 12 m Omega respectively, The conductive polymer hip-chip bonding technique developed in this work shows a very low contact resistance, simple processing steps, a high bumping alignment resolution (<+/-5 mu m), and a lower bonding temperature (similar to 170 degrees C), This new bonding technique has high potential to replace conventional flip-chip bonding technique for sensor and actuator systems, bio/chemical mu-TAS, optical MEMS, OE-MCM's, and electronic system applications.