Research On Thermal Design And Thermal Analysis Of Communication Equipment

In order to meet the high forwarding rate and fast processing speed requirements, highpackaging density chips are widely used in the core backbone network communicationequipment. If the heat cannot be dispatched properly, excess temperature will cause manyserious problems such as bit errors, packet loss, crash and even burn out the chips. Therefore,the research on thermal design and thermal analysis is very essential to assure the highreliability of communication equipment. Thermal analysis based on the CFD can help usdiscover the thermal risk and improve the thermal solution during the early stage of productdevelopment, and accelerate product development.The main difficulty of thermal analysis lies in establishing an appropriate thermal model.Firstly, this thesis researched the thermal property of some complicated components such asPCB, chip, heat pipe and thermal interface, and built equivalent thermal model. The flowresistance and thermal resistance of heat sinks were characterized though numericalsimulation test, and a volume resistance compact model of heat sink was constructed. Theavailability of the compact model was verified with results of detailed model.Secondly, thermal simulation analysis of a high-power switch was conducted by usingAnsys Icepak software. Due to the complexity of the chassis, a simplified board model wasused in the system-level thermal analysis. The fan operating point and each slot air volumeflow was gained by the system-level thermal simulation, and some optimization suggestionwas proposed to reduce the system pressure impedance. Then a detailed board-level thermalanalysis was conducted under slot air flow boundary condition. The temperature field,velocity field and chip junction temperature was accurately calculated. The impact ofchanging heat sink fin gap, fin thickness and chip layout design on the chip junctiontemperatures are examined. To verify thermal simulation model and result, temperaturetesting of the prototype was conducted, the result presented that the deviation of test resultand simulation result is less than10%, proved that the thermal model and simulation resultsare reasonable.At last, we established the analytic model of thermal resistance and flow resistance of a plate-fin heat sinks using heat transfer and friction correlation, analyzed the impact of variousparameters on the characteristics of the heat sink, and optimized the fin number, fin thicknessfin length and fin height to achieve the minimum thermal resistance and the minimum heatsinks mass.