Conversion‐Controlled Poly(Ionic Liquid)/Aluminum Nitride Thermal Interface Materials with Internal Plasticization for Reliable Chip‐Level Thermal Management

ABSTRACT The increasing power densities of artificial intelligence and high‐performance computing (HPC) chips place stringent demands on thermal interface materials (TIMs), which are designed to combine efficient heat transport with interfacial conformability, stress relaxation, and long‐term reliability. Conventional silicone‐based TIMs can suffer from oil bleeding, pump‐out, and insufficient adhesion during prolonged thermal exposure. Here, a conversion‐controlled poly(ionic liquid)/aluminum nitride (PIL/AlN) thermal gel is developed by partially polymerizing the PIL matrix. The resulting chain‐entangled PIL framework retains residual monomer and oligomer species that provide internal plasticization, promote interfacial wetting, and facilitate stress relaxation, while densely packed spherical AlN particles establish heat‐transfer pathways. After optimization of polymerization time and filler loading, the 55 vol% AlN composite exhibits an elongation‐at‐break of 291%, adhesion strengths of 5.4 MPa on Cu and 3.7 MPa on Si, and a bulk thermal conductivity of 2.0 W·m −1 ·K −1 . Its mechanical compliance enables intimate contact with Si, yielding an interfacial thermal resistance of (2.93 ± 0.96) × 10 −6 K·m 2 ·W −1 . T3Ster cycling and high‐temperature aging further show stable device‐level thermal responses and no detectable macroscopic defects under the tested conditions. This conversion‐controlled strategy provides a route to silicone‐free TIMs that combine mechanical compliance, interfacial adhesion, low interfacial thermal resistance, and operational stability.