Study Of The Impact Of Surface Channels On Interfacial Thermal Resistance For Packaging

Interfacial thermal resistance has a significant impact on thermal management of electronic device packaging, and it plays an important role in the total packaging thermal resistance. Particle-filled thermal interface materials which are widely used in electronic devices packaging,have the advantages of high thermal conductivity, low cost, easy to operate, etc., and they can effectively reduce the interfacial thermal resistance in thermal management of packaging. Drawbacks of these materials are the stacking of particles, formation a thick bondline thickness(BLT), and the susceptibility to air voiding and cohesive crack in the thermal cycling, on the contrary to increase the thermal resistance of thermal interface materials(RTIM).Surface channels can significantly improve the above problems which particle-filled thermal interface materials have encountered in the applications. In this thesis, the surface channels are chosen as the research object and the main work are as follows:(1) Firstly, the definition, function and research progress of thermal interface materials in industry have been reviewed, the problems which particle-filled thermal interface materials encountered in their applications have also been introduced; Secondly, the principle of surface channels reducing BLT through decreasing pressure gradient and preventing particle stacking has been demonstrated on the basis of fluid flow theory.(2) An experimental method designed for evaluating the impact of surface channels on thermal resistance has been proposed, which by testing thermal resistance of the TIM(RTIM) in a solid-solid contact interface which may have surface channels and making comparison between them. The test results shows that surface channels can significantly reduce the thermal resistance of TIM(RTIM), in some cases of the test experiments the decreasing amplitude can be up to 56.1%. (3) For the interface used the TIM which has relatively low thermal conductivity, surface channels can lead more decrease on RTIM. The reason is that the decreased BLT caused by surface channels have greater thermal resistance.(4) Increasing the pressure on the thermal interface also can significantly reduce the RTIM. Furthermore, for the interface used the TIM which have lower thermal conductivity, the trend of decreasing of RTIM is more remarkable.(5) Surface channels reduced the BLT, removed part of the material in the solid-solid interface which have relative high thermal conductivity, and increased the heat transfer area between the thermal interface. In this thesis, finite element method(FEM) has been used to simulate the impact of this changes on the interfacial thermal resistance. The results showed that surface channels can also significantly reduce the interfacial thermal resistance, the simulation results agree well with the experiments.It is expected that the surface channels and its assessment methods proposed in this thesis have some reference value on the design of thermal management of electronic device packaging.