This study examines experimentally the quality of contact of mechanical joints in a diode heat sink assembly. Steady-state contact conductance, h, is used as a quantitative measure of the quality of contact of a joint. The emphasis of the work is on determining the contact conductance, h, for a nonideal joint using a noncontact method of recording temperature distribution in a complex geometry. Thermal contact conductance for an interface is known to depend on parameters such as contact pressure, mean interface temperature and the surface roughness characteristics of the mating surfaces. The results are presented for three different conditions of the interface namely (i) the mating surfaces are bare (ii) aluminum foil is inserted between the mating surfaces, and (iii) a high thermal conductivity grease is applied to the mating surfaces. Two levels of contact pressure are used for the interface with aluminum foil. The results indicate that the contact conductance increases with the mean temperature of the interface in all the cases. At low interface temperature, the contact conductance was greatest for the bare interface conditions. At high interface temperature, the contact conductance was greatest for the aluminum foil interface condition.

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