An advanced packaging technology (developed over 40 years ago) which has begun to generate renewed interest is the solder-bumped flip chip technology. This interconnection method offers significant advantages over other traditional packaging technologies of wire- and tape-automated-bonding. Some of the competitive advantages of flip-chip include the capacity to accommodate a much higher pin count (due to area versus perimeter-only bonding), enhanced electrical and thermal performance, a self-alignment capability at a more relaxed I/O pitch which leads to a lower cost and more manufacturable process, compatibility with current surface mount technology (SMT), and the relative ease in the reworking of defective die....[ Read more ]

An advanced packaging technology (developed over 40 years ago) which has begun to generate renewed interest is the solder-bumped flip chip technology. This interconnection method offers significant advantages over other traditional packaging technologies of wire- and tape-automated-bonding. Some of the competitive advantages of flip-chip include the capacity to accommodate a much higher pin count (due to area versus perimeter-only bonding), enhanced electrical and thermal performance, a self-alignment capability at a more relaxed I/O pitch which leads to a lower cost and more manufacturable process, compatibility with current surface mount technology (SMT), and the relative ease in the reworking of defective die.

In this thesis we will detail a successful combination of materials and processes which were developed for fabrication of eutectic lead-tin solder bumps. The potential for realizing a low cost solder bumping process using conventional electroplating and reflow techniques in conjunction with a flip chip assembly process will be presented in detail. Initial results with the flip-chip bonding of specially designed "daisy-chain" solder bumped test die together with preliminary electrical and mechanical characterization of the bonded parts will also be discussed.

This research has proven the feasibility and development of a low-cost solder-bumped process for flip-chip applications. We have found that a manufacturing scale implementation of this technology may be possible provided that the materials and process parameters are properly chosen and controlled.