Mechanically Compliant Thermal Interfaces Using Biporous Copper‐Polydimethylsiloxane Interpenetrating Phase Composite

Abstract Thermal interface materials are essential for thermal management in electronics packaging by providing a low resistance thermal pathway between heat sources and heat sinks. Nanostructured materials can be potential candidates for the next‐generation interface materials by coupling their high thermal conductivity and mechanical compliance, suppressing failure even after large numbers of thermal cycles. This work investigates the thermal and mechanical characteristics of a new type of thermal interface materials, consisting of metal/elastomer interpenetrating phase composites. The 3D, highly porous copper scaffolds are fabricated via a fast and simple in situ bubble‐templated electrodeposition process without the presence of solid templates; subsequently, the void fraction of the composite is filled by elastomer infiltration. The presence of elastomer matrix demonstrates limited impact on the thermal conductivity of the composite while it contributes substantially to the mechanical properties, providing the structural flexibility required. Thermal resistance values of 1.2–4.0 cm² K W^–1 are measured upon multiple thermal cycles, confirming the mechanical stability of the composite, without showing any noticeable degradation.