Temperature Cycle Test System Based On Gap Flow Heat Exchange Mechanism

With the rapid development of integrated circuits, precision machining and MEMS technology, electronic products have been developing towards miniaturization for many years. However, as the decrease of volume and the increase of power, the temperature of micro electronic devices fluctuates easily, and the change of temperature causes the variation of the structure and parameters of materials, which makes the products performance changed. During the entire process of design, production, transportation and use, electronic products face all kinds of thermal environment, and especially the alternative temperature environment worsens the products performance. Therefore, temperature cycle test is an important method of quality tests and runs through the whole life cycle of products. So miniature, energy-efficient and reliable temperature cycle test system has significant research values. The thesis designs a set of small temperature cycle test system according to the demand of micro electronic products temperature environment test, and applies the system to the fatigue test of MEMS full cells.Firstly, temperature cycle test is a way to inspect products qualities, and for different products and different application environment, the parameters of temperature test are different. On the basis of the analysis about national standard, military standards and international standards of temperature environment test in electronic industry and combination, according to practical demand, the temperature rang of the test system is set from5℃to70℃, and the test system could satisfy two kinds of test requirements which include stipulated time of temperature conversion and stipulated rate of temperature change. On this basis, this thesis has designed overall solutions of the system, and completing the design of three-module structure, high temperature module, low temperature module and heat exchanger.Secondly, the heating method of getting constant temperature liquid is studied and the plate heater with serpentine channels is designed and the manufacture and assembly heater and other matched liquid circulation apparatus are accomplished. After contrastively analyzing the advantages and disadvantages of various refrigeration methods, the compressor refrigeration scheme is adopted to refrigerate the liquid. Refrigerating unit with power of500W and temperature range from-20℃-40℃is defined. To satisfy efficient and energy-efficient requirements,a novel heat exchanger based on the gap flow heat exchange mechanism of single phase flow is designed. The heat exchange performance influenced by the gap width and the flow velocity of heat-conducting medium is analyzed. The result shows that the heat exchanger with0.4mm wide gap is considered to have better combination property. At last, the heat exchanger which the gap width is0.4mm is built to make a comparison of the CFD simulation and experimental results. The results has shown that the average temperature rise rate exceeds5℃/min and the instantaneous temperature rise rate can reach20℃/min, and the average convective heat-transfer coefficient is ranged from90to130W/(m2-℃), which accomplish the design goals.Lastly, liquid circulation control overall scheme is designed, and the design and experiment of route layout, liquid circulation control and temperature cycle control are finished. The entire system is finally set up and used for temperature cycle test stipulated time of temperature conversion and stipulated rate of temperature change of5-50℃and5-70℃. The experimental result reached the prospective goal and coincided with the standard temperature curve. Temperature cycle tests ranged from5℃to70℃of two MEMS fuel cells were carried out by the system, the variation of internal resistance of cells under different cycle times are measured. Over8cycles, the internal resistance of both cells gradually increases, and both of them finally lead to failure. The results have shown that the temperature cycle test system based on gap flow heat exchange mechanism developed in this article can well accomplish temperature cycle reliability test of micro/mini components such as MEMS fuel cells.