A Flip-chip attach method for dense, moderate pin count, high speed (80+ Gbps) interconnects

W. L. Wilkin, M. J. Lorsung, J. E. Bublitz, B. A. Randall, J. L. Fasig, E. S. Daniel, B. K. Gilbert

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Scopus citations

Abstract

State of the art SiGe BiCMOS processes have enabled the development of complex integrated circuits capable of supporting very high speeds (e.g. 100+ Gbps digital). While packaging strategies for lower pin count integrated circuits using thin film ceramic or similar substrates have been utilized widely, the more complex circuits realizable in SiGe technology; require larger numbers of high speed interconnects, presenting new packaging challenges. We have demonstrated a flip-chip attach process, whereby gold stud bumps are applied to silicon integrated circuits with aluminum pads and attached using an ACF (Anisotropic conductive film, Sony FP1708E) interposer to a polvmer-based LCP (Liquid Crystal Polymer) multilayer substrate for high speed (S0+ Gbps) applications. The primary demonstrated interconnect used 60 micron stud bumps on a 150 micron pad pitch; a tighter pad pitch could be realized but was relaxed to compensate for a constrained LCP metal etch process. A design of experiments (DOE) was used to determine an optimum ACF cure temperature of 190° C with 6S80 grams offorce for the attach process. The ACF material was shown to serve as a very robust underfill attach material, with good adhesion to the LCP substrate through temperature cycling up to 245°C. The conductive electrical path (primarily through a thermocompression bond of the gold bump to the aluminum pad with minimal occurrence of conductive material from the ACF), exhibited a per-interconnect loss of 1.2 to 1.7 dB at 40 GHz for the particular geometries used.

Original languageEnglish (US)
Title of host publicationProceedings - 2006 International Symposium on Microelectronics, IMAPS 2006
Pages633-639
Number of pages7
StatePublished - Dec 1 2006
Event39th International Symposium on Microelectronics, IMAPS 2006 - San Diego, CA, United States
Duration: Oct 8 2006Oct 12 2006

Publication series

NameProceedings - 2006 International Symposium on Microelectronics, IMAPS 2006

Other

Other39th International Symposium on Microelectronics, IMAPS 2006
CountryUnited States
CitySan Diego, CA
Period10/8/0610/12/06

Keywords

  • Anisotropic conductive film (ACF)
  • Flip-chip
  • Gold stud bump
  • Liquid crystal polymer (LCP)

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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