Flip chip attachment of silicon devices using substrate ball bumping and the technology evaluation on test assemblies for 20 Gbit/s transmission

Ball bumping is a fast and flexible method for bumping of single devices because only a modified wire bonding machine can be used. In this paper the flip chip TC-attach of silicon devices using substrate gold ball bumping was investigated. The results show that thermal compression flip chip attachment between the aluminum pad metallization and gold ball bumps can be achieved. The interconnection was characterized by infrared microscopy and shear testing. To demonstrate the capability of the technology developed, flip chip test assemblies with silicon bipolar ICs for high speed signal transmission were realized. The assemblies were investigated by TDR (Time Domain Reflectometry), reflection-loss and eye-pattern measurements and compared to wire bond species. As a result of these investigations it was found, that the flip chip technology developed in this paper can be used and is an excellent approach especially for rapid prototyping. With the test assemblies realized, 20 Gbit/s signal transmission could be demonstrated successfully.