Patent ID: 8071494

Claim:
A glass substrate for flat panel display, which is formed by a float method, which has a composition consisting essentially of, in terms of oxide amount in mass %: SiO 2 50 to 72%, Al 2 O 3 0.5 to 15%, MgO + CaO + SrO + BaO 4 to 30%, Na 2 O more than 0% and at most 10%, K 2 O 1 to 21%, Li 2 O 0 to 1%, Na 2 O + K 2 O + Li 2 O 6 to 25%, ZrO 2 0 to 10%, and Fe 2 O 3 0.0725 to 0.15%; and wherein the average Fe 2+ content in a surface layer of the glass substrate within a depth of 10 Î¼m from a top surface is at most 0.0725% in terms of Fe 2 O 3 amount.