A heat exchanger including a collecting tank having an outwardly extending flange around an edge, a tube plate having a connection edge, tubes having ends extending into openings in the tube plate, and an intermediate plate having an edge lying against the connection edge of the tube plate. The connection edges of the intermediate plate and the tube plate are both mechanically connected to the flange of the collecting tank. Pins in the corners of one of the tube plate and the intermediate plate secure the tube plate and intermediate plate together. The connection edge of the plates include protrusions bendable onto the edge flange of the collecting tank.