Patent ID: 8921245

Claim:
A glass substrate comprising, in mass percent based on the oxides: from 68 to 81% of SiO 2 , from 0.2 to 18% of Al 2 O 3 , from 0 to 3% of B 2 O 3 , from 0.2 to 11% of MgO, from 0 to 3% of CaO, from 0 to 3% of SrO, from 0 to 3% of BaO, from 0 to 1% of ZrO 2 , from 1 to 18% of Na 2 O, from 0 to 15% of K 2 O, and from 0 to 2% of Li 2 O, wherein Al 2 O 3 +K 2 O is from 7 to 27%, Na 2 O+K 2 O is from 11.5 to 22%, MgO+CaO+SrO+BaO is from 0.2 to 14%, MgO+0.357Al 2 O 3 −0.239K 2 O−5.58 is from −3.0 to 1.5, Na 2 O+0.272Al 2 O 3 +0.876K 2 O−16.77 is from −2.0 to 2.5, a glass transition temperature is 500° C. or higher, and an average thermal expansion coefficient at from 50 to 350° C. is less than 85×10 −7 /° C.