Title page for ETD etd-10312005-163634

Type of Document Dissertation
Author Bai, Guofeng
Author's Email Address gbai@vt.edu
URN etd-10312005-163634
Title Low-Temperature Sintering of Nanoscale Silver Paste for Semiconductor Device Interconnection
Degree PhD
Department Materials Science and Engineering
Advisory Committee
Advisor Name Title
Lu, Guo-Quan Committee Chair
Boroyevich, Dushan Committee Member
Corcoran, Sean Gerald Committee Member
Reynolds, William T. Jr. Committee Member
van Wyk, Jacobus Daniel Committee Member
  • Silver joint
  • Reliability
  • Lead-free solution
  • Semiconductor device interconnection
  • Low-temperature sintering
  • Electronic packaging
  • Nanoscale silver paste
Date of Defense 2005-10-21
Availability unrestricted
This research has developed a lead-free semiconductor device interconnect technology by studying the processing-microstructure-property relationships of low-temperature sintering of nanoscale silver pastes.

The nanoscale silver pastes have been formulated by adding organic components (dispersant, binder and thinner) into nano-silver particles. The selected organic components have the nano-particle polymeric stabilization, paste processing quality adjustment, and non-densifying diffusion retarding functions and thus help the pastes sinter to ~80% bulk density at temperatures no more than 300°C. It has been found that the low-temperature sintered silver has better electrical, thermal and overall thermomechanical properties compared with the existing semiconductor device interconnecting materials such as solder alloys and conductive epoxies. After solving the organic burnout problems associated with the covered sintering, a lead-free semiconductor device interconnect technology has been designed to be compatible with the existing surface-mounting techniques with potentially low-cost. It has been found that the low-temperature sintered silver joints have high electrical, thermal, and mechanical performance. The reliability of the silver joints has also been studied by the 50-250°C thermal cycling experiment. Finally, the bonging strength drop of the silver joints has been suggested to be ductile fracture in the silver joints as micro-voids nucleated at microscale grain boundaries during the temperature cycling.

The low-temperature silver sintering technology has enabled some benchmark packaging concepts and substantial advantages in future applications.

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