The Research Of Experimental And Modeling On Thermal Interface Resistance And Its Application In Notebook Thermal Design

Heat will pass through a multitude of interfaces when heat flows from chips to environment in most of the electronic equipments. The solid microscopic surface is roughness. The real contact only occurs in a fraction of small discrete microscopic asperities when two surfaces contact each other. It will lead the constriction of the heat flow when heat flows through the contact interface, causes an additional resistance for the heat transfer, namely thermal contact resistance. At present domestic and overseas scholars research the thermal interface resistance through the experiment in the vacuum, the operation is inconvenient.We built an experiment device for measuring thermal interface resistance with microchannel heat sink. The loading is active and can be controlled accurately without using the pressure sensor. The microchannel heat sink can sufficient ensure the heat flow along the one-dimensional and axial, improving the accuracy of measurement. The influences of the interface temperature, loads and thermal interface material on the thermal interface resistance is studied. The experimental results show that the thermal interface resistance decreases with the increase of loads and interface temperature; the greater the root mean square roughness is, the greater the thermal interface resistance will be; the material can effectively reduce the solid contact thermal interface resistance. The error analysis is carried on.According to the single point contact theory and the theory of contact mechanics, the theory formula of the thermal interface resistance is derived. Compared the predicted and experimental results, the results show that the magnitude of theoretical and experimental values are 10-4m2K/W, agrees well. We built the thermal interface resistance model with the flows interface material according to the theory of solid surface morphology and the ideal gas law. The magnitude of the thermal interface resistance between specimens and interface material is 10-6m2K/W, the thermal-conduction resistance of interface materials is major factor when the solids carried on heat transfer.Because of high heat flux and high temperature in notebook computers, a numerical computational model of notebook based on the thermal interface resistance theory is built. The temperature field and velocity field inside system is simulated for the purpose of thermal structure optimization. Results show that the thermal interface resistance will reduce the heat dissipation effect of the thermal module, rise the chip temperature and thermal resistance; the active cooling and passive cooling can respectively take 30.3 W and 4.7 W away from the CPU under full load conditions; the fin spacing is set to 1 mm, the thickness is set to 0.4 mm, which can effectively improve the cooling effect; increasing the fan flows, extending the vent area and the lower environment temperature can improve the heat dissipation capability of the system.We design a passive cooling system with graphene for the notebook, the CPU, graphics, north bridge and motherboard are placed on the back of LCD screen, other components are still decorated inside the casing, the numerical results show that the CPU, graphics and chipset maximum temperature are 57 ℃, 55.3 ℃ and 55 ℃, respectively with natural convection. The microchannel heat sink and serpentine-finned radiator is applied in notebook, the maximum temperature of the CPU, graphics and north bridge chip is 30.5℃, 28.5℃ and 30.1℃ at the inlet flow rate of 1m/s, the temperature is 25℃. Therefore, the water cooling and are cooling can be combined effectively to solve the heat dissipation problem of the notebook.