Abstract: The invention relates to a method for the manufacture of a plate heat exchanger/cooler (1), and to an arrangement for a plate heat exchanger/cooler produced by furnace brazing. When finished, the heat exchanger exhibits a number of passageways (2-7) communicating in parallel via collectors (8a) and intended for a fluid which is cooled. Each of the passageways (2-7) consists of a pair of plates (2a, 2b, . . . 7a, 7b) facing one another. These have openings (2a2, 2b2, . . . 7a2, 7b2) arranged on the ends which, in the finished heat exchanger/cooler, constitute the aforementioned collectors (8a). Spacer washers (10) which define flow openings (10a) for a cooling medium are present between pairs of plates situated adjacent one another. The spacer washers (10) and the plates (2a, 2b, . . . 7a, 7b) and the pairs of plates are joined together at least along their outward-folded edges (2a1, 2b1, . . . 7a1, 7b1) by a furnace brazing process.