Substrate for thin film electroluminescent display panel

A method for preparing an electroluminescent (EL) display element comprising the steps of:

• providing a glass substrate made of borosilicic acid;
• subjecting at least one surface of said glass substrate to a first primary grinding;
• subjecting said at least one surface of said primary ground glass substrate to a second grinding of a photo-mask grade,
• cleaning said ground surface of said glass substrate with a non-acidic solution followed by drying with freon vapors such that said prepared surface of said glass substrate is free of hydrolytic products;
• and
• providing in succession a transparent electrode formed on said cleaned surface of said glass substrate, first and second dielectric layers defining therebetween a EL thin film, and a counter electrode formed on said second dielectric layer so as to prepare said electroluminescent display element.