Determining Material Parameter of Solder Alloys by Nanoindentation

Environmental awareness motivates the replacement of traditional plumbiferous solder joints in microelectronic devices by new material alloys. In our group mechanical properties of some lead-free alloys are determined by nanoindentation experiments. We use a Microsystems-Nanoindenter Machine with Berkovich tip and apply standard techniques to extract the material properties from the measured load-displacement curves. To assess the quality of our experimental results we model and analyze the setup by finite element computations. By comparing the real (input) material data with the results determined from the load-displacement curves we analyze the obtained data in dependence of strength and stiffness of the materials under consideration. For low-strength material we point out deviations. By inverse analysis we adapt numerically elastic modulus and yield stress to experimentally measured load-displacement curves. To obtain information on the material's work hardening we suggest the use of a blunt indenter tip, e.g., a spherical indenter. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)