特集論文 Inelastic Constitutive Relationship of Electroplated Nickel Films at Elevated Temperatures for Design of Micro Connector (特集:MEMS/NEMS材料特性および信頼性評価)

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This paper describes elevated temperatures tensile strength and inelastic constitutive relationship of electroplated nickel (Ni) thin films used in high-density micro connectors. The compact tensile tester operated in Scanning Probe Microscope (SPM) evaluated mechanical properties of electroplated Ni specimens, with nominal dimensions of 15 μm in thickness, 50 μm in width and 600 μm in length, at elevated temperatures. All specimens have line patterns on their specimen gauge section to measure axial elongation under tensile loading with an SPM cantilever. Strain rates faster than 5 %/sec were employed to obtain the time-independent Youngs modulus and yield stress of the Ni specimens. Averaged Youngs modulus was closed to that of a bulk of Ni, however ultimate tensile strength showed a larger value. Yield stress and breaking elongation were also quite different from previous reported values of the bulk. Inelastic constitutive equations were proposed as a function of temperature in order to reveal inelastic deformation behavior of the Ni micro connector at elevated temperatures in finite element analyses.
2005-07-01