Method of attaching electronic components by soldering with removal of substrate oxide coating using a flux, corresponding substrate and corresponding flip-chip component

A method of attaching an electronic component (202) to a metal substrate (204) such as a lead frame, wherein the electronic component (202) comprises an exposed solder region comprising a solder bump (206) and flux (208) thereon, the method comprising: forming a metal-based compound layer (210) (a metal oxide, metal sulphide or metal nitride layer) on the metal substrate (204); placing the electronic component (202) on the metal substrate (204) such that the solder region is in contact with a contact region of the metal-based compound layer (210); and heating the solder region such that the contact region of the metal-based compound layer (210) dissolves under the influence of the flux (208) and the reflowed solder bump (206) forms an electrical connection between the electronic component (202) and the metal substrate (204). The metal-based compound layer (210) can have a minimum thickness of 10 nm. The provision of the metal-based compound layer (210) on the metal substrate (204) may prevent or reduce excessive flow-out of flux (208) and/or solder (206) during heating in the reflow process.