Micro-ball bumping technology for flip chip and TAB interconnections

A new bumping method using micro-balls was developed that can be used for high-density LSI assembly, specifically, for the TAB interconnection and Flip Chip interconnection. Using this method, gold and solder balls with the diameter ranging from 35μm to 150 μm are first formed with a high level of accuracy and sphericity. These balls are then attached to the through-holes of the arrangement plate by vacuum suction so positioned as to match the positions of electrodes where bumps need to be formed, and are aligned and bonded to the electrodes of an LSI chip or substrate. This method has made possible the formation of gold bumps for TAB and Flip Chips and solder bumps for Flip Chip with high efficiency and precision.