Coefficient of thermal expansion of stressed thin films
(Institute of Mechanics, School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China)
Abstract: A new technique was proposed to determine the coefficient of thermal expansion (CTE) of thin films at low temperature. Different pre-stress could be applied and the elastic modulus of materials at different temperatures was measured with CTE simultaneously to eliminate the influence of mechanical deformation caused by the pre-stress. By using this technique, the CTEs of polyimide/silica nanocomposite films with different silica doping levels were experimentally studied at temperature from 77 K to 287 K, and some characteristics related to this new technique were discussed.
Key words: thin film; thermal expansion coefficient; polyimide; elastic modulus; stress