A thermal interface device comprises a film of thermal grease intended to be inserted between a first object and a second object, and a microporous seal encircling the periphery of the film of thermal grease. A manufacturing method comprises steps of: deposition of the microporous seal on the first object in such a way as to form a closed frame on the first object; deposition of the thermal grease on the first object, inside the closed frame; smoothing of the thermal grease bearing on the frame of microporous seal, making it possible to form the film of thermal grease encircled by the microporous seal; and deposition of the second object on the film of thermal grease.