13th International Conference on Fracture June 16–21, 2013, Beijing, China -2- mass of creep test data at elevated temperatures [9]. However, these studies only revealed the properties of sintered silver film, which in turn imposed a limitation to consider the thermally induced strain due to thermal expansion coefficient mismatch between substrate and chip in actual applications. Li et al. [10, 11] constructed a lap-shear structure to study the mechanical property of sintered nano-silver as a joint. Following this lap-shear structure, further research on fatigue and dwell-fatigue property of sintered nano-silver joint was conducted in this study. Not only tensile and fatigue tests but also creep-fatigue tests were conducted in this article in order to understand the failure mechanism of nano-silver sintered lap shear joint at elevated temperature, study any possible relation between creep and fatigue in the low-cycle regime and learn the probabilistic observed mechanisms The creep-fatigue tests were conducted at the temperature of 325℃, at which both dwell time and fatigue process interacted and failure occurred in the low-cycle regime. 2. Sample preparation and experiment procedure Details about lap-shear joint preparing have been presented elsewhere [11]. The well prepared sintered nano-silver structure with 2mm×1mm×50μm joint used in this study is showed in Fig. 1. All the tests were conducted on Micro Uniaxial Fatigue Testing System (MUT-1020) provided by CARE Measure & Control Co., Ltd. as shown in Fig. 2. Fig. 1 Prepared sintered nano-silver lap-shear structure Fig.2 The testing apparatus In order to obtain the shear stress-strain relations of sintered lap shear joints as the base for cyclic tests, a series of shear tests were conducted at four different ambient temperatures of 25℃, 225℃, 275℃ and 325℃. For fatigue and dwell-fatigue tests, the loading conditions are listed in Table 1. 3 samples were conducted for each loading condition. All the shear and cyclic tests were conducted under stress-controlled mode with loading rate of 2MPa/s.
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