Abstract: The invention relates to a heat exchanger for carrying out a thermal exchange between a first fluid and a second fluid. The heat exchanger includes a plurality of chambers stacked in a longitudinal direction to form a thermal exchange bundle. At least one first chamber suitable for containing the first fluid is defined by a pair of first plates, and at least one second chamber suitable for containing the second fluid is defined by a pair of second plates. The second plates including openings in communication with the second chamber The first plates each include at least two primary openings and at least two secondary openings The two primary openings being in communication with the first chamber, and the two secondary openings being in communication with the openings of the second plates.