Mechanical characterization of solution-derived nanoparticle silver ink thin films
Mechanical properties of sintered silver nano-particles are investigated via substrate curvature and nanoindentation methods. Substrate curvature measurements reveal that permanent microstructural changes occur during initial heating while subsequent annealing results in nearly-elastic behavior of the thinner films. Thicker films were found to crack upon thermal treatment. Coefficient of thermal expansion was determined from linear slopes of curvature curves to be 1.9 ± 0.097 ppm/oC, with elastic modulus and hardness determined via nanoindentation. Accounting for substrate effects, nanoindentation hardness and modulus remained constant for different film thicknesses and did not appear to be a function of annealing conditions. Hardness of 0.91 GPa and Modulus of 110 GPa are ~ 20% lower than expected for a continuous nanocrystalline silver film, most likely due to porosity.
Greer, J. R. ; Street, R. A. Mechanical characterization of solution-derived nanoparticle silver ink thin films. Journal of Applied Physics. 2007 May 29; 101: 103529.