Boosted heat dissipation efficiency by sandwich structure containing the thermally conductive segregated network in phase change materials for advanced chip thermal management

The thermal conductivity (λ) determines the response rate of composite phase change materials (CPCMs) to the external heat, which is essential for chip thermal management. Traditional methods, such as blending thermal conductive fillers into PCMs, have limited success in enhancing λ, often failing to meet practical application requirements. This study introduces a novel approach combining physical blending and compression molding to create a sandwich structure with isolated heat conduction paths in CPCMs. The upper and bottom layers consist of expanded graphite (EG) films, while the middle layer is n-octacosane encapsulated by graphene nanoplatelets (GnP) and polydimethylsiloxane (PDMS). The superior in-plane λ of EG films ensures rapid heat spreading, thereby reducing overheating risks. The GnP-coated n-octacosane particles construct an isolated network structure during molding, providing efficient heat conduction paths. Furthermore, the strong interfacial bonding between GnP and EG films reduces interfacial thermal resistance, establishing an uninterrupted heat conduction pathway that bolsters heat transfer. This structure significantly endows the CPCMs with high λ to 9.82 W/(m·K), 39 times higher than pure n-octacosane (0.25 W/(m·K)). The CPCM also demonstrates a high latent heat of fusion of 189.3 J/g and excellent shape stability with only a 2.3 % loss in fusion enthalpy after 30 thermal cycles. In a laboratory-based chip thermal management system, the CPCM extends the chip temperature range from 30 °C to 70 °C by 239 %, demonstrating outstanding thermal performance. This study proposes a novel strategy for preparing high thermally conductive CPCMs, with significant potential for advanced chip thermal management.