Green Tape Automation. Teilvorhaben: Untersuchung einer Flip-Chip-Technik auf Mehrlagen-Keramik-Substraten Abschlussbericht

Abstract

The Flip Chip bonding technology offers numerous advantages compared with other, more conventional interconnection methods. In particular, the short interconnect distances allow fast signal response behaviour. Additional Flip-Chip bonding offers a very high interconnection density, the possibility to place connections over the whole active area of the flip chip bonded device and the possibility of self alignment. The FC mounting technology on green tape ceramic substrates offers economical and flexible solutions for a wide industrial application of multi chip modules including consumer products and industrial applications like automotive, telecommunication and medical electronic systems. The application of FC-technology on greentape multilayer substrates requires adapted metallization systems on substrate and chip. Fluxless soldering is possible directly on different thick film pattern metallizations. Concerning the process optimization and reliability investigations the Flip-Chip bonding experiments were performed using special test chips and test substrates. In order to study the thermomechanical behavior of the joints FEM-simulations were performed. In the project two bumping processes based on electroplated Au/Sn and Pb/Sn solders were developed. The bonding process was performed with the flip-chip bonder FC-950 from Carl Suess. For a fluxless soldering process, special aspects of reference were formulated. The fluxless flip chip bonding experiments were performed on different thick film metallization using substrates with an excellent flatness. The best mechanical and electrical results are achieved with Au/Sn solder bumps mounted on Pd/Ag metallizations. The influence of the contact height and the chip size on reliability were investigated by thermal cycling. The reliability of the joints could be significantly increased if an adequate underfill material was applied. This could be demonstrated by thermal cycling and ATC-testing of the fluxless mounted and encapsulated chips. In summary it could be shown that the application of a fluxless flip chip bonding technology with Au/Sn solder bumps on Pd/Ag thick film metallizations of Green Tape multilayer ceramic substrates is a promising interconnection method and opens new applications in the scope of advanced microsystems technologies. (orig.)SIGLEAvailable from TIB Hannover: F95B791 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman