The increasing power dissipation density in modern microelectronics, particularly 5G chips, necessitates highly efficient thermal management systems. Conventional cooling technologies, such as air or liquid cooling, face challenges in achieving rapid heat transfer due to multilayer architectures and interfacial thermal resistance. These passive systems struggle with efficient cooling at low-temperature differentials, requiring additional cooling units. Electrocaloric cooling, an active and solid-state refrigeration technology, offers a promising alternative. It utilizes the reversible thermal change of ferroelectric materials upon application or removal of an electric field. Polymeric ferroelectrics are attractive due to their excellent electrocaloric performance, flexibility, and ease of large-scale fabrication. However, their inherent low thermal conductivity, stemming from chain conformation and arrangement, limits their effectiveness, particularly at high switching frequencies. This research addresses this limitation by introducing a continuous three-dimensional (3-D) thermal conductivity network within the electrocaloric polymer to enhance both active cooling and passive heat dissipation.

Existing literature highlights the challenges of thermal management in high-power density microelectronics, particularly 5G chips. Conventional passive cooling methods, such as air or liquid cooling, are reviewed, emphasizing their limitations in terms of heat transfer efficiency and the need for large temperature differentials. The advantages of electrocaloric cooling as an active, solid-state alternative are discussed, along with the recent progress in polymeric ferroelectrics. However, the low thermal conductivity of these polymers is identified as a major bottleneck, affecting the cooling performance, especially at higher frequencies. Previous research on enhancing thermal conductivity in polymer matrices through the incorporation of various fillers is reviewed, setting the stage for the proposed approach of using a 3D conductive network.

This study combines an electrocaloric polymer with a 3-D network of lead-free ferroelectric ceramic (BCZT) to create an interpenetrating composite (3-3 PCC). The 3-D ceramic network acts as both nucleation sites for polar domains and a high-speed pathway for phonon transport. The P(VDF-TrFE-CFE) polymer films were prepared by dissolving the polymer in DMF, casting onto a glass substrate, and annealing to enhance crystallinity. The 3-D ceramic network was fabricated using a sol-gel method, with the BCZT sol infiltrated into a polyurethane foam template, followed by calcination. The electrocaloric effect (ECE) was characterized using an in-situ calibrated measurement system, determining isothermal entropy change (ΔS) and adiabatic temperature change (ΔT). Finite element method (FEM) simulations were used to analyze heat transfer in the composite. A scaled-up electrocaloric refrigeration device prototype was fabricated, employing electromagnetic actuation to switch the electrocaloric stack between a heat source and a heat sink. The device's cooling performance was evaluated using a heat flux sensor and infrared thermal imaging, simulating the heat dissipation of a 5G chip.

The 3-3 PCC composite exhibited a significant enhancement in electrocaloric performance (240% increase in ΔT and ΔS compared to the neat polymer) and thermal conductivity (300% increase). The introduction of the 3-D ceramic network increased the number of polar nanodomains in the polymer and facilitated the transition from non-polar to polar phases under lower electric fields. FEM simulations confirmed the superior heat transfer capabilities of the 3-D network structure compared to discontinuous filler dispersion. The electrocaloric device prototype, operating at a low electric field (30 MV m⁻²), achieved maximum heat fluxes of 288 W m⁻² (heating) and -272 W m⁻² (cooling) at 0.1 Hz. At 1 Hz, an average cooling heat flux of -213 W m⁻² was achieved. In a 5G chip cooling simulation, the device reduced the chip surface temperature from 71.4 °C to 63 °C, preventing it from reaching the high-risk temperature range for chip failure (70-80 °C).

The results demonstrate the synergistic effects of the 3-D heat-conductive network and electrocaloric refrigeration in enhancing chip thermal management. The 3-D network addresses the limitations of low thermal conductivity in electrocaloric polymers, improving both passive heat dissipation and active cooling efficiency. The significant enhancement in electrocaloric performance at low electric fields allows for the operation of the device at voltages compatible with typical semiconductor chips. The successful demonstration of chip cooling using the device prototype highlights the potential of this technology for practical applications in next-generation microelectronics.

This study successfully demonstrated a novel approach to enhance the thermal management capabilities of electrocaloric polymers by incorporating a 3-D heat-conductive network. The resulting composite material exhibits significantly improved electrocaloric performance and thermal conductivity, leading to a highly effective chip cooling device prototype. This work opens new avenues for developing efficient and scalable thermal management solutions for high-power density microelectronic devices. Future research could explore the optimization of the 3-D network structure, investigation of other electrocaloric materials and polymer combinations, and the development of integrated thermal management systems for advanced computing applications.

The current study focused on single heat spot cooling. Further research is needed to explore the scalability of this approach for managing heat dissipation from multiple heat sources on a chip. The long-term stability and reliability of the electrocaloric device under continuous operation also require further investigation. The specific choice of materials and fabrication methods might influence the optimal performance of the device. Finally, a comprehensive cost-benefit analysis comparing this technology with other existing cooling techniques is recommended.