Method of producing a soldered plate heat exchanger block having a plurality of heat exchange passages for indirect heat exchange between at least two fluids, wherein the plate heat exchanger block is composed of separator plates , sidebars and heat-conducting structures as components , wherein the heat-conducting structures have or form a corrugated structure with alternately arranged corrugation top lands and corrugation flanks , and wherein the corrugation top lands are arranged parallel to each other, having the following steps: - arranging the components in a stack by arranging in parallel the separator plates with the sidebars and heat-conducting structures being inserted between the separator plates , wherein a respective heat exchange passage is bordered by at least two sidebars , and wherein in each case, a first contact surface of the sidebars lies against a contact region of an adjacent separator plate , and a further second contact surface facing away from the first contact surface lies against another contact region of a further adjacent separator plate , and wherein a contact surface of the corrugation top lands of the respective heat-conducting structure(s) in each case lies against an associated contact region of the adjacent separator plates , - soldering the stack , characterized in that before the components are arranged in the stack, solder material (L) is applied to one or more of the components of the plate heat exchanger block in such a way - that the respective contact surface and/or the respective contact region is formed from solder, and - that, in an examination after arranging the components in the stack and before soldering the stack , surface regions which are located on one side (4.1, 4.2) of a respective separator plate between the contact regions and/or the contact surfaces are free of a solder layer (L) or are not in contact with a solder layer (L). - arranging the components in a stack by arranging in parallel the separator plates with the sidebars and heat-conducting structures being inserted between the separator plates , wherein a respective heat exchange passage is bordered by at least two sidebars , and wherein in each case, a first contact surface of the sidebars lies against a contact region of an adjacent separator plate , and a further second contact surface facing away from the first contact surface lies against another contact region of a further adjacent separator plate , and wherein a contact surface of the corrugation top lands of the respective heat-conducting structure(s) in each case lies against an associated contact region of the adjacent separator plates , - soldering the stack , characterized in that before the components are arranged in the stack, solder material (L) is applied to one or more of the components of the plate heat exchanger block in such a way - that the respective contact surface and/or the respective contact region is formed from solder, and - that, in an examination after arranging the components in the stack and before soldering the stack , surface regions which are located on one side (4.1, 4.2) of a respective separator plate between the contact regions and/or the contact surfaces are free of a solder layer (L) or are not in contact with a solder layer (L). <EOS>