摘要
Adhesiveless materials are commonly used for electric or portable products that require high flexibility during operation. This structure incorporates a copper substrate and polyimide film. For life-time studies, the key aspect to evaluate is the effect of the thermal factors. In general, techniques to measure the life-time of the materials involve storing samples over a long term period in order to monitor changes; however, this is time-consuming. The aging test is an alternative method to predict and evaluate the changes in the mechanic properties over a short term period; yet the test conditions influence the accuracy of the results. The temperature and relative humidity (RH) are the major parameters for the test, and the test conditions of 85°C/85% RH and 150°C will be discussed in this paper. It is observed that the lifetime of rolled-annealed copper foil with polyimide film is significantly higher than metal films produced by other common methods, and the results are explained using the analysis of the fracture mechanics. From comparing the test data with samples stored for three years, the best prediction was achieved with conditions of 85°C/85% RH; with errors of less than 5%. The best flexibility was achieved when the optimum thickness of the copper and polyimide was determined.