Beyond Planar Graphene: Roughness‐Conforming Microlaminates Enable Superior Heat Removal

The escalating cooling demands of high‐heat‐flux electronic systems require materials that deliver efficient heat spreading, phase‐change enhancement, and scalable manufacturability—capabilities rarely found simultaneously on a single platform. Here, we introduce a microlaminate strategy that translates graphene's intrinsically two‐dimensional phonon transport into three‐dimensional heat removal from localized hot spots, without relying on volumetric composites or geometry‐dominated architectures. As a representative implementation, we demonstrate graphene‐based microlaminates integrated with laser‐microstructured copper, where the metal serves as a technologically relevant model substrate rather than a fundamental constraint. The interface‐engineered microlaminates preserve graphene's ultrahigh in‐plane thermal conductance, while enabling efficient coupling to macroscopic heat‐rejection pathways. Experiments and supporting analyses reveal exceptional performance across multiple thermal‐management regimes: (a) ∼20% reduction in hotspot temperature under single‐phase liquid cooling at heat fluxes approaching ∼150 W cm −2 , (b) ∼15% enhancement in heat‐transfer coefficient during dropwise condensation, and (c) record in‐plane effective thermal conductivity of ∼1.5 × 10 4 W m −1 K −1 in vapor‐chamber heat spreaders – among the highest reported for thermal‐management devices to date. While copper is employed here as a model system, the microlaminate framework is material‐agnostic and readily extendable to other thermally conductive substrates, establishing a general pathway for integrating planar nanomaterials into three‐dimensional thermal platforms.