Sequential roll-gap expansion enables highly aligned h-BN networks for enhanced thermal management in polymer composites

초록

Efficient lateral heat spreading is critical for mitigating localized hot spots in highly integrated electronic devices, yet polymer-based thermal interface materials (TIMs) are often limited by insufficient filler alignment and discontinuous heat-transfer pathways. Here, a sequential roll-gap expansion strategy was investigated to control thermal-network formation in highly filled PDMS/h-BN composites while maintaining the selected h-BN loading, roll-speed condition, and final roll gap. Power-law rheology and lubrication-based analysis suggested that the gap-expansion pathway influences shear transfer within the film interior, while SEM and XRD analyses confirmed enhanced h-BN orientation relative to composites processed at a fixed roll gap. The resulting in-planealigned h-BN network increased the thermal conductivity from 5.4 to 10.3 W center dot m- 1 center dot K- 1 and promoted more rapid lateral heat spreading, as supported by transient thermal simulations and IR thermography. In LED-based thermal-management tests, the highly aligned composite reduced the LED surface temperature by 28.0 degrees C compared with pristine PDMS and by 9.0 degrees C compared with the random composite at 9 V, while maintaining the lowest temperature under additional electrical input powers of approximately 2.3 and 20 W. These results demonstrate that thermal transport is governed not only by filler loading or the final processing condition, but also by the pathway used to reach that condition. This work establishes processing-path control as a simple and scalable thermal-engineering strategy for constructing efficient heat-transfer networks in high-performance TIMs, without additional external fields or chemical modification.

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