Lead-free Solder foil for diffusion soldering, for connecting metallic Structural components and/or for connecting metallised/metal-coated Structural components, i.e. for connecting metallic Surface coatings of adjacent Structural components to one another, characterised in, - that the lead-free Solder foil is comprised of a compact Composite solder material, and this compact, i.e. firmly-bonded, rigid, Composite solder material is composed in such a way, that in a lead-free soft solder environment, of a Soft solder matrix made of tin (Sn), Particles of a high-melting point Metallic component, of a hard soldering component made of copper (Cu) and/or nickel (Ni), are distributed and dispersed, such that each of the Particles is surrounded completely by lead-free Soft solder, in order that in a customary soldering process, with typical soldering profiles for lead-free soldering, full conversion of lead-free Soft solder of the Soft solder matrix is effected in Intermetallic Phases, which have a melting temperature of over 400°C, and - that the dispersed Particles distributed in the Soft solder matrix of the high-melting temperature Metallic component display a thickness of 3 μm to 20 μm in the direction of the foil thicknesses, wherein the separation distances of the Particles from one another in the Soft solder matrix are 1 μm to 10 μm, and each of the Particles of the high-melting temperature Metallic components are enveloped on all sides by a 1 μm to 10 μm thick layer of the Soft solder, and - that the proportion of soft solder, the Soft solder matrix, in relation to the proportion of high-melting temperature Metallic component is not higher than is necessary during synthesizing of Intermetallic Phases, wherein this ratio of the percentage of Particles arranged in Composite solder material of the high-melting temperature Metallic components to the percentage share of Soft solder of the lead-free Soft solder matrix which surrounds the Particles in accordance with the stoichiometric formula from the Intermetallic Phases to be formed from the respective starting materials which must be determined in such a way, that the entirety of the Soft solder of the lead-free Soft solder matrix is converted in the respective built-up intermetallic phases, and - that the entire thickness of the lead-free Solder foil is 20 μm to 0,5 mm, and - that the Solder foil and the Composite solder material, have a Jacket sheath alongside the metallic Surface coating of the Structural components which must be joined, whose coating thickness is between 2 μm and 10 μm and is composed of Soft solder. - that the lead-free Solder foil is comprised of a compact Composite solder material, and this compact, i.e. firmly-bonded, rigid, Composite solder material is composed in such a way, that in a lead-free soft solder environment, of a Soft solder matrix made of tin (Sn), Particles of a high-melting point Metallic component, of a hard soldering component made of copper (Cu) and/or nickel (Ni), are distributed and dispersed, such that each of the Particles is surrounded completely by lead-free Soft solder, in order that in a customary soldering process, with typical soldering profiles for lead-free soldering, full conversion of lead-free Soft solder of the Soft solder matrix is effected in Intermetallic Phases, which have a melting temperature of over 400°C, and - that the dispersed Particles distributed in the Soft solder matrix of the high-melting temperature Metallic component display a thickness of 3 μm to 20 μm in the direction of the foil thicknesses, wherein the separation distances of the Particles from one another in the Soft solder matrix are 1 μm to 10 μm, and each of the Particles of the high-melting temperature Metallic components are enveloped on all sides by a 1 μm to 10 μm thick layer of the Soft solder, and - that the proportion of soft solder, the Soft solder matrix, in relation to the proportion of high-melting temperature Metallic component is not higher than is necessary during synthesizing of Intermetallic Phases, wherein this ratio of the percentage of Particles arranged in Composite solder material of the high-melting temperature Metallic components to the percentage share of Soft solder of the lead-free Soft solder matrix which surrounds the Particles in accordance with the stoichiometric formula from the Intermetallic Phases to be formed from the respective starting materials which must be determined in such a way, that the entirety of the Soft solder of the lead-free Soft solder matrix is converted in the respective built-up intermetallic phases, and - that the entire thickness of the lead-free Solder foil is 20 μm to 0,5 mm, and - that the Solder foil and the Composite solder material, have a Jacket sheath alongside the metallic Surface coating of the Structural components which must be joined, whose coating thickness is between 2 μm and 10 μm and is composed of Soft solder.