Abstract: This heat exchanger includes fluid circulation channels extending lengthwise along a first axis, and layers that are flat and superposed on one another along a second axis. To improve performance, each layer is made up of metal strips so the strips a layer all extend lengthwise perpendicular to the second axis and adjacent one another, without necessarily touching. Each channel is jointly defined by first through third layers, the second being intercalated, along the second axis, directly between the first and third layers so each channel is delimited by a face of the first and third layers and edges of the second layer running parallel to the first axis and transversely to the second layer, these edges being formed by strips of this second layer fusion-welded to the first and third layers in zones extending along the length of the channel and situated on either side of the channel.

Abstract: Disclosed is a method in which flat layers are produced in succession so each newly produced layer is stacked on a previously produced layer or on a flat metal support, each layer having at least one metal strip occupying the entire thickness of the corresponding layer. The production of each layer includes: deposition, during which part of the strip is pressed against the previously produced layer or the support; a fusion step carried out during the deposition step during which only a fused portion of the part is fusion-welded to the previously produced layer or to the support; and repeating the deposition and fusion steps, applying them to corresponding parts of the or each strip offset from each other along a second axis perpendicular to the first axis, such that the fused portions of two of the parts following each other along the second axis overlap.