A substrate is coated on one face with a thin-films stack having reflection properties in the infrared and/or in solar radiation including at least one metallic functional layer, based on silver or on a metal alloy containing silver, and at least two antireflection coatings. The coatings each include at least one dielectric layer. The functional layer is positioned between the two antireflection coatings. The stack also includes a terminal layer which is the layer of the stack which is furthest from the face. The terminal layer is a metallic layer consisting of zinc and tin, made of SnxZny with a ratio of 0.1≤x/y≤2.4 and having a physical thickness of between 0.5 nm and 5.0 nm excluding these values, or even between 0.6 nm and 2.7 nm excluding these values.