Patent ID: 8377834

Claim:
A glass composition for substrates, which is characterized by comprising, as represented by mass% based on oxides, from 55 to 75% of SiO 2 , from 5 to 15% of Al 2 O 3 , from 4 to 18% of MgO, from 3 to 12% of CaO, from 4 to 18% of SrO, from 0 to 20% of BaO, from 6 to 20% of Na 2 O+K 2 O, from 0.5 to 6% of ZrO 2 and from 18 to 25% of MgO+CaO+SrO+BaO, as a glass matrix composition, and containing from 0.001 to 0.6% of SO 3 , and which is further characterized in that when the viscosity is represented by η, the temperature satisfying logη=2 is at most 1,545° C. and the devitrification temperature is at most the temperature satisfying logη=4, the thermal expansion coefficient is from 75×10 −7 to 90×10 −7 /° C., the specific gravity is at most 2.8, and the glass transition point is at least 600° C.