Modeling plated copper interconnections in a bumpless flip chip package

The bumpless flip chip package (BFCP) is a novel integrated circuit (IC) package which employs an electrochemical process to form plated copper interconnections between the IC-to-substrate chip-level assembly. This unique packaging process does not require wire bonding or solder bumped flip chip interconnection procedures. The plated copper chip interconnection provides a robust connection, which is redistributed with nickel coated copper traces without an interposer substrate to compliant terminals in an area array package. The plated copper interconnections in the BFCP addresses reliability concerns by providing a stronger micro-joining alternative to wire bonding or flip chip soldering. The unique compliant redistribution design in the BFCP is expected to improve the solder joint reliability performance at board-level assembly. Package-level thermal cycling tests and analysis were conducted, along with finite element modeling and simulation of the BFCP subject to package-level temperature cycling.