A substrate is coated on one face with a thin-film multilayer including at least one metal functional film based on silver or made of silver having a thickness e of between 7 nm and 20 nm inclusive of these values, and two antireflection coatings. The antireflection coatings each include at least one antireflection film. The functional film is placed between the two antireflection coatings. The multilayer includes two discontinuous metal films each having a thickness e′ of between 0.5 nm and 5 nm inclusive of these values. A lower discontinuous metal film is located between the face and the only or first metal functional film as counted starting from the face and an upper discontinuous metal film located above the only or last metal functional film as counted starting from the face.