The invention relates to a fluid channel for a heat exchanger, comprising a metal sheet, wherein the metal sheet has at least one core region of an aluminum base alloy and at least one structure arranged inside the fluid channel, wherein the structure lies against a surface of the metal sheet and can be soldered to the metal sheet in a flux-free manner by way of a first soldering location in a soldering operation, and wherein a soldering region of the metal sheet and a counterpart lie against one another and can be soldered to one another in the same soldering operation as a second soldering location while wetting with flux, wherein an open path between the two soldering locations exists before the soldering operation.