Patent ID: 7685716

Claim:
A heat exchanger obtained by: joining thin heat exchanging plates of an iron-based material, which heat exchanging plates have a heat exchanging area and, optionally, a distribution area, and which heat exchanging plates are provided with port holes and a pressing pattern of elevations and depressions over the heat exchanging area of the plates and, if present, over the distribution area, the heat exchanger plates being coated with an active brazing material on 5-40% of the heat exchanging area and, if present, the distribution area, prior to the joining the plates, which active brazing material comprises melting point lowering elements, and the plates are arranged in such way that contact points between adjacent elevations and depressions are obtained, and the plates being brazed together in the formed contact points; wherein the contact points include at least one of point-shaped contact points and lined-formed contact points, and wherein active brazing material is selectively applied to less than all of the at least one of point shaped contact points and line formed contact points.