Quantitative characterization of porosity and determination of elastic modulus for sintered micro-silver joints

High resolution serial block-face scanning electron microscopy has been performed on sintered micro-silver pastes that are used as lead replacement joints for die bonding. The size and spatial distributions of the porosity before and after ageing were determined by quantification of the segmented 3D images. The elastic modulus was determined by an image-based finite element model and validated by results obtained from a dynamical resonance method. In agreement with contemporary analytical models on the elastic behaviour of porous materials, the elastic modulus was found to be a function of pore fraction only. Ageing the specimens does not alter the density or Young's modulus.