Flip-chip interconnection technology for advanced thermal conduction modules

Area array solder bumps on silicon devices, known as C4 balls, have been successfully used in terminating logic and memory devices to ceramic substrates in numerous IBM products over two decades. With the IBM System 390/ES9000 series of mainframe computers, this highly reliable chip termination technology has achieved improved interconnection density and total number of chip I/O connections per module. In addition, in the models 820 and 900 of ES9000 series, a novel materials set, namely glass-ceramic with Cu internal metallization along with thin-film redistribution wiring on top, has been introduced for multilayered ceramic substrates. Key elements of advanced glass-ceramic substrate technology relevant to flip-chip joining are reviewed. This is followed by a discussion of device join and replace processes used in advanced thermal conduction modules which also have decoupling capacitors which are attached by C4 solder reflow. Optimization of the top surface metallurgy and device join parameters necessary to achieve reliable joining of more than 70000 solder balls per module is discussed