Morphological evolution of intragranular void under the thermal-stress gradient generated by the steady state heat flow in encapsulated metallic films: Special reference to flip chip solder joints

Ogurtani T. O., Akyildiz O.

Symposium on Theory, Modeling and Numerical Simulation of Multi-Physics Materials Behavior held at the 2007 MRS Fall Meeting, Massachusetts, United States Of America, 26 - 30 November 2007, vol.139, pp.151-155 identifier identifier

  • Publication Type: Conference Paper / Full Text
  • Volume: 139
  • Doi Number: 10.4028/
  • City: Massachusetts
  • Country: United States Of America
  • Page Numbers: pp.151-155
  • Middle East Technical University Affiliated: Yes


The morphological evolution of intragranular voids induced by the surface drift-diffusion under the action of capillary forces, electromigration (EM) forces, and thermal stress gradients (TSG) associated with steady state heat flow is investigated in passivated metallic thin films via computer simulation using the front-tracking method. As far as the device reliability is concerned, the most critical configuration for interconnect failure occurs even when thermal stresses are low if the normalized ratio of interconnect width to void radius is less than certain range of values (which indicates the onset of heat flux crowding). This regime manifests itself by the formation of two symmetrically disposed finger shape extrusions (pitchfork shape slits) on the upper and lower shoulders of the void surface on the windward side. The void growth (associated with supersaturated vacancy condensation) on the other hand inhibits anode displacement but enhances cathode and shoulder slit velocities drastically, which causes lateral spreading.