Abstract: The main object of the invention is a heat exchanger including a first header plate of an inlet manifold, a second header plate of a distribution header and a heat exchange core bundle extending between the first header plate and the second header plate along a longitudinal direction, the heat exchange core bundle being defined by a shell and having a plurality of tubes arranged successively next to each other in a transverse direction, each tube being capable of cooperating with the header plates via through-holes formed in each plate. The shell has at least one longitudinal end with a straight edge configured to be in flat surface contact with at least one header plate in a contact area, the surface contact occurring mainly in a plane perpendicular to the longitudinal direction.