The effect of electrodeposition process parameters on residual stress-induced self-assembly under external load
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2014 IOP Publishing Ltd. The authors (Boyd et al 2007 J. Micromech. Microeng. 17 452-61) presented a methodology for using residual stresses due to mismatch strains as a means of self-assembling microstructures under external loading during material deposition. Assembly of two components was considered: one component was subjected to deposition and was modeled as an Euler-Bernoulli beam, and the other component was not deposited and was modeled as a linear spring. This work experimentally extends Boyd et al (2007 J. Micromech. Microeng. 17 452-61) to account for the effects of process conditions, specifically the electrodeposition current density and temperature, which affect both the Young's modulus and the mismatch strain. First, nickel was electrodeposited onto an atomic force microscope (AFM) cantilever, and the cantilever deflections at various current densities and temperatures were measured by using the resonance method of AFM and the measured deformation of the cantilever was converted into the quantitative mismatch strain by appropriate mechanics. For a given deposition thickness, the magnitude of the mismatch strain increased with increasing current density or plating temperature. The Young's modulus decreased with increasing current density and increased slightly with increasing temperature. Next, the self-assembly model was experimentally verified by electrodepositing nickel onto an AFM cantilever beam in contact with a second AFM beam, serving as the spring, that does not undergo deposition. For a given deposition thickness, the spring deflection increased with increasing current density and increasing deposition temperature.