Heat exchanger comprising flanges

A heat exchanger for a motor vehicle having a bundle of tubes (2) and spacers interposed between the tubes in the bundle to promote heat exchange, the bundle being delimited by two end spacers (70, 71), the exchanger also having two header plates, designed to have the ends of the bundle passing through them, and at least one side plate (50, 51) positioned on one of the end spacers, characterized in that the side plate has at least one expansion area (80) to compensate for the longitudinal expansion of the side plate, and in that the cross section of the side plate in the expansion area is substantially U-shaped, wherein the side plate has a substantially flat central web (500), bordered by two longitudinal flanges (501, 502), the flanges (501, 502) being connected to the central web (500) in the expansion area (80), and wherein the expansion area (80) comprises an opening (800) formed in the central web (500) and two lateral bends (871, 872) pointing towards an inside of the side plate, the lateral bends being positioned on either side of a longitudinal axis of the side plate (a) and each lateral bend extending over part of the flanges and over a corresponding part of the area of connection of the flanges to the central web.