A study on high thermal conductivity thermal interface materials with aligned metal oxide nanomaterials

Abstract

Integration and high performance of semiconductor device have been accelerating following Moore’s law, and generate large amount of heat in the device. A typical method to managing heat of device is using heat sink, but the layer of air, which formed by incomplete contact between device and heat sink caused by the roughness of surface, acts as thermal resistance to deteriorate heat dissipation. A thermal interface material (TIM) is a substance that reduces thermal resistance between a heat source and heat sink, which facilitates heat conduction toward the outside. Recently, the TIMs are fabricated by loading thermally conductive filler in polymer matrix, because of easy process, light weight, and low cost. A metal oxide material is widely used TIM filler due to low electrical conductivity, low thermal expansion coefficient, stable, and low cost. To improve the thermal conductivity of TIM, not only the type of filler but also the arrangement structure of filler particles is important part. By arranging filler particles, a thermal path is efficiently formed to conduct heat effectively, which can achieve high thermal conductivity at low filler concentration. In this study, a TiO2 nanospheres and Zn2SnO4 (ZTO) microspheres are applied for filler particles and forming heat dissipation arrangement structure. The TiO2 nanospheres filler/monolayer-based TIM was fabricated via facile processes such as icing method and spin-coating. Thermal conductivity of the fabricated TiO2 nanosphere-based TIM was enhanced by increasing the concentration of the TiO2 NS-filler and successfully cooling down the GPU chip temperature from 62℃ to 50℃. Moreover, the TIM with the TiO2 monolayer additionally lowered the GPU temperature by 1–7℃. The COMSOL simulation results show that the TiO2 monolayer, which was in contact with the heat source, reduces thermal resistance and boosts the heat transfer characteristics from the heat source toward the inside of the TIM. The vertically aligned ZTO MS-based TIM was fabricated by synthesizing ZTO-Fe3O4 particles using hydrothermal method and aligning ZTO-Fe3O4 MS by magnetic field in PDMS matrix. The ZTO-Fe3O4 MS-based TIM showed remarkable heat dissipation ability and lowered GPU temperature from 91.6℃ to 73.2℃ in high load on GPU chipset. Furthermore, when the fillers were vertically aligned, the heat dissipation ability of ZTO-Fe3O4 MS based TIM was improved and lowered GPU temperature to 20.12~43.74% compared to not aligned one. This heat dissipation performance improvement by aligning filler stem from efficiently forming thermal path with the minimal particles that increase the number of thermal path and reduce phonon scattering during heat transfer in TIM. The suggested metal oxide-based TIM with effective arrangement structure that improve heat dissipation characteristics can reduce the temperature of the device without an additional filler loading, and it is expected to have a wide range of applications for the thermal management of advanced device.