Analytical Homogenization for Microelectronic Substrates

Organic substrates used in microelectronic packages contain complex micro-via, plated-through-hole via, and copper networks in order to accommodate stringent electrical requirements of power delivery and I/O. These complex layouts can produce significant inhomogeniety in the in-plane and out-of-plane mechanical properties of the substrates. An analytical homogenization methodology has been established that uses substrate design geometries and material properties such as the copper density and via locations with two-phase micromechanics models to homogenize the substrate. In this paper the homogenization methodology is discussed and validated with experimental data. A comparison of the various two-phase micromechanics models commonly found in literature are reviewed and compared for their applicability to accurately homogenize organic substrates. Two case studies are provided to highlight the importance of accurately modeling the anisotropy of the substrates for temperature cycling and bend reliability predictions.