The Interaction Between an Imposed Current and the Creep of Idealized Sn-Ag-Cu Solder Interconnects
Skip to main content
eScholarship
Open Access Publications from the University of California

UC Berkeley

UC Berkeley Previously Published Works bannerUC Berkeley

The Interaction Between an Imposed Current and the Creep of Idealized Sn-Ag-Cu Solder Interconnects

Abstract

The work reported here concerns the effect of an imposed current on the creep of simple Sn-Ag-Cu interconnects. The samples employed were double-shear specimens that contained paired solder joints, 400 μm × 400 μm in cross-section, 200 μm in thickness, on Cu. Different representative microstructures were prepared by electromigration and isothermal aging. Samples were tested with and without an imposed current, and at a variety of temperatures. These tests consistently yield two unexpected results. First, the relative increase in creep rate with current was nearly the same over a range of temperatures and variety of starting microstructures. Second, when tests were done at the same temperature (including the effect of Joule heating), the rate of creep was lower under imposed current than under isothermal conditions. These results are explained in the light of new data that show that the temperature within the joint is almost constant, even under a relatively high current density of 5500 A/cm2. Given constant temperature and a microstructure that includes interfacial voids, the current depletes the joint of vacancies, lowering the␣average creep rate, and introducing observable heterogeneities in the creep pattern. The usual Dorn equation then provides a very useful basis for evaluating the change of creep rate with current.

Many UC-authored scholarly publications are freely available on this site because of the UC's open access policies. Let us know how this access is important for you.

Main Content
For improved accessibility of PDF content, download the file to your device.
Current View