Patent ID: 7754631

Claim:
An alkali metal-free glass substrate, comprising substantially no alkali component or BaO and consisting essentially of, as represented by mol% based on oxide, from 57.0 to 65.0% of SiO 2 , from 10.0 to 12.0% of Al 2 O 3 , from 6.0 to 9.0% of B 2 O 3 , from 5.0 to 10.0% of MgO, from 6.0 to 8.0% of CaO and from 2.5 to 5.5% of SrO, provided that MgO+CaO+SrO is from 16.0 to 19.0%, MgO/(MgO+CaO+SrO)≧0.40, and B 2 O 3 /(SiO 2 +Al 2 O 3 )≦0.12; wherein Young's modulus ≧75 GPa; the linear expansion coefficient at from 50 to 350° C. is from 30×10 −7 /° C. to 40×10 −7 /° C.; the strain point ≧640° C.; the temperature T 2 (the viscosity η satisfies logη=2) is at least 1,580° C. and at most 1,620° C.; the temperature T 4 (the viscosity η satisfies logη=4) ≦1,245° C.; the devitrification temperature ≦T 4 ; and weight loss per unit area is at most 0.2 mg/cm 2 , when immersed in 0.1N HCl at 90° C. for 20 hours.