NOVELTY - A glass composition is melted to form a glass melt (5) and the glass melt is formed into a flat glass in the form of a glass ribbon. The flat glass is conveyed to an annealing chamber and annealed. During formation of glass ribbon or before or during or directly after annealing of the flat glass, at least one surface of the flat glass is treated with a gaseous or liquid stream either for exchanging smaller mass ions by larger mass ions in a surface layer of the flat glass or for reactively removing sodium ions from the surface layer of flat glass.    USE - Production of flat glass e.g. glass pane useful as substrate in electronic device with thin-film solar cell (all claimed). Can also be used as cover plate or base plate.    ADVANTAGE - The method requires less additional heat to achieve the ion-exchange reactions or chemical reactions for removing sodium ions in the allotted process time. The reduction of concentration of sodium ions in the surface layer also improves the weathering resistance of the flat glass by reducing the incidence of sodium hydroxide reactions at the surface of flat glass. The migration of sodium ions is significantly reduced and the disturbance of electrical devices due to the migration of sodium ions is significantly reduced. The reduced sodium ion transfer secures that the rate of loss of photovoltaic cell efficiency over the lifetime of photovoltaic cell and the loss of efficiency of coatings used on an architectural solar glass is avoided. The obtained flat glass has excellent mechanical property.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) glass pane having a thickness of 3.2 mm or less, preferably 2.4 mm or less; and    (2) electronic device.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view explaining the flat glass production using a treatment unit for applying a gaseous or liquid flow onto a glass ribbon.    Glass furnace (4)    Glass melt (5)    Tin bath chamber (8)    Molten tin/molten tin alloy (9)    Application unit (20)