This paper presents the results and conclusions from tensile tests performed on four lots of microtensile specimens produced by the LIGA method. The specimens tested are 3 millimeters long, 0.2 millimeters wide and 0.2 millimeters thick. The specimen is held in specially designed grips, and friction is eliminated by the use of a linear air bearing in the load train. Strain is measured by laser interferometry between two Vickers microhardness indentations placed 0.2 millimeters apart in the center of the specimen. Two sets of pure nickel specimens from two different Microelectronics Center of North Carolina (MCNC) LIGA Multi-User MEMS Process (LIGAMUMPs) runs were tested along with one set of pure nickel specimens from the HI-MEMS Alliance. In addition, four tests were conducted on a 0.03 millimeter thick nickel-iron alloy with a target composition of 78% Ni, 22% Fe. One set of LIGAMUMPs specimens had an average Young's modulus of 181 GPa, which was almost exactly the same as measured on the HI-MEMS material. However, the other set showed a much lower modulus of 158 GPa. Modulus measurements of the nickel-iron alloy were inconclusive. The two LIGAMUMPs materials had yield and ultimate strengths on the order of 330 and 530 MPa respectively, while the HI-MEMS material was stronger at 420 MPa and 600 MPa. The nickel-iron alloy was considerably stronger, with a yield strength of 1.8 GPa and an ultimate strength of 2.4 GPa.
William N. Sharpe,
"Tensile properties of LIGA nickel", Proc. SPIE 3512, Materials and Device Characterization in Micromachining, (1 September 1998); doi: 10.1117/12.324092; https://doi.org/10.1117/12.324092