QA17 Copper Alloy Micro Flat Springs Fabricated By Cold Extrusion And Its Properties

Along with the technology of MEMS is used in all walks of life, the market scale of MEMS is expanding with an unbelievable speed. Micro electro mechanical system is the combination of various micro parts, so the key to develop MEMS is the technology of micro parts forming. As the significance mechanical structure, micro flat spring provide elastic force and transfer energy, which is the same as normal one. In this paper, the material is commercially high strength QA17 aluminium bronze, the mechanical property of alloy withearly heat treatment at room temperature was discussed, the preparation is cold extrusion forming, and forming state, the evolution of microstructure and properties of micro flat spring varied with forming processes. The main conclusions are as follows:In the compression test at room temperature, the QA17 copper alloy exist the grain size effect and feature size effect on the compression yield strength. In the tensile test, there are an obvious size effect only at the specimen thickness ranged from 0.25mm to 0.5mm in the tensile yield strength.A crude spring pillar of QA17 copper alloy with 8 mm of length,2 mm of width,0.5mm of line width was manufactured by cold extrusion. The required micro spring which is 0.5mm of thickness was created after cutting the crude spring. The lubrication makes a great difference to on the forming progress of micro spring. Good lubrication can reduce the forming load and make micro spring have good shape, gloss surface. Early heat treatment process and extrusion speed have little impact on the forming quality of micro spring.Grain deformational degree on the edges of the spring was much higher than that on the center of the spring. The part have a significance distribution of flow line near cantilever. The micro-hardness, elastic stiffness and fatigue life can be affected by technological parameter and crack which was created by stress concentration. The circulation service life of micro flat spring that forming by QA17 copper alloy is up to 19260 with the highest. That is much better than the Ni microflat spring which form by LIGA.