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Effect of thermal interface materials on temperature distribution in cryogenic stage
Woo-Jae Choi, Yojong Choi, Seunghyun Song, Seung-Young Park and Yeon Suk Choi

We experimentally investigate the thermal performance of thermal-link configurations between the second-stage cold head of a compact GM cryocooler and a sample stage for wide-range temperature control. To quantify the cooling performance, heaters were installed on the first and second stage of the cold-head, and a cooling-capacity map was obtained under various heat-load conditions. Sapphire, fiber-reinforced plastic (FRP) with Cu-plated through holes (Cu PTHs), and their hybrid stack were employed as thermal interface materials (TIMs) with different temperature-dependent thermal conductivities. The temperature difference between the second-stage cold head and the sample stage was systematically compared among TIM configurations under steady-state heating. Sapphire provided efficient cooling at low temperatures but generated only a limited temperature difference at elevated temperatures. In contrast, FRP with Cu PTHs produced a larger thermal resistance, and the hybrid configuration achieved a temperature difference of 102.5 K, raising the sample stage to 430.2 K. These results provide practical guidelines for TIM selection and sample-stage design in compact conduction-cooled systems.

Keywords: thermal interface materials, cryogenic stage, GM cryocooler, wide-range temperature control, temperature distribution, sapphire, fiber-reinforced plastic with Cu-plated through holes