Patent ID: 7786035

Claim:
A glass substrate consisting of a glass composition that comprises, in mass %, 40 to 70% SiO 2 , 5 to 20% B 2 O 3 , 10 to 25% Al 2 O 3 , 0 to 10% MgO, 0 to 10% CaO, 0 to 20% SrO, and 0 to 10% BaO, and further comprises greater than 0.06% R 2 O, and greater than 0% and no greater than 1.5% Cl, where R is at least one selected from Li, Na, and K, and Li 2 O falls in a range of 0 to 0.5%, Na 2 O falls in a range of 0 to 0.5%, and K 2 O falls in a range of 0.05 to 1.5%, all in mass %, wherein the content of K 2 O is at least two times the content of Na 2 O.