Heat exchanger with protected thin edges, especially for a motor vehicle

A heat exchanger comprising a matrix having a multiplicity of fins positioned parallel to each other and a plurality of tubes extending through the fins, the fins together defining two side faces at opposite ends of the matrix, the fins having lateral notches formed therein, the heat exchanger further comprising at least one lateral traverse member having a U-shaped cross section and having a central spine portion, two side branches projecting from opposite sides of the spine portion, and an anchor hook at the end of each side branch, the anchor hooks being configured to engage with the lateral notches of the fins, whereby the at least one traverse member covers one of the side faces of the matrix, wherein the spine portion is substantially flat and has an internal face facing the matrix, and the spine portion further comprising a longitudinal rib on the internal face for abutting against the side face of the fins.