Ultralow Interfacial Thermal Resistance of Graphene Thermal Interface Materials with Surface Metal Liquefaction

Developing advanced thermal interface materials (TIMs) to bridge heat-generating chip and heat sink for constructing an efficient heat transfer interface is the key technology to solve the thermal management issue of high-power semiconductor devices. Based on the ultra-high basal-plane thermal conductivity, graphene is an ideal candidate for preparing high-performance TIMs, preferably to form a vertically aligned structure so that the basal-plane of graphene is consistent with the heat transfer direction of TIM. However, the actual interfacial heat transfer efficiency of currently reported vertically aligned graphene TIMs is far from satisfactory. In addition to the fact that the thermal conductivity of the vertically aligned TIMs can be further improved, another critical factor is the limited actual contact area leading to relatively high contact thermal resistance (20-30 K mm(2) W-1) of the solid-solid mating interface formed by the vertical graphene and the rough chip/heat sink. To solve this common problem faced by vertically aligned graphene, in this work, we combined mechanical orientation and surface modification strategy to construct a three-tiered TIM composed of mainly vertically aligned graphene in the middle and micrometer-thick liquid metal as a cap layer on upper and lower surfaces. Based on rational graphene orientation regulation in the middle tier, the resultant graphene-based TIM exhibited an ultra-high thermal conductivity of 176 W m(-1) K-1. Additionally, we demonstrated that the liquid metal cap layer in contact with the chip/heat sink forms a liquid-solid mating interface, significantly increasing the effective heat transfer area and giving a low contact thermal conductivity of 4-6 K mm(2) W-1 under packaging conditions. This finding provides valuable guidance for the design of high-performance TIMs based on two-dimensional materials and improves the possibility of their practical application in electronic thermal management.

Automated summary

Developing advanced thermal interface materials (TIMs) based on graphene is critical for solving the thermal management problem of high-power semiconductor devices. However, the current vertically aligned graphene TIMs have low heat transfer efficiency and limited contact area. In this study, a three-tiered TIM composed of vertically aligned graphene and liquid metal cap layers was designed, resulting in high thermal conductivity and increased effective contact area. This finding provides valuable guidance for the practical application of high-performance TIMs in electronic thermal management.