Design and Fabrication of a Micro Spring with Steel Structures for the Microtensile Testing of Thin Films

Abstract

A novel micro spring with steel structures is described here. It can be fit into a specially designed microtensile apparatus, which is capable of carrying out a series of tests on micron scale freestanding thin films. This method is suitable for thin metal films or polymer layers with large strain and can be applied to samples with different thicknesses. The novel fabrication method uses the conventional lithography and electrochemical metal etching techniques. A single photomask is used to define the whole structure, resulting in a simple and inexpensive fabrication process. The method proposed here is promising for the low cost fabrication of micro spring based on steel. A micro spring of 100μm wide, 100μm thick, with 200μm diametric of the semicircle and 6 turns was prepared by this method; the elasticity of the spring is 147.3N / m. A gold wire was measured by this micro spring. The young's modulus and ultimate tensile strength of the gold wire were 30Gpa and 120Mpa, respectively.