| 摘要 |
The present invention pertains to an alkali-free glass substrate reduced in thickness by at least 5 µm using hydrofluoric acid (HF) etching to yield a plate thickness of no more than 0.4 mm, wherein the alkali-free glass substrate has a relative elastic modulus of at least 32 MNm/kg and a photoelastic constant of no more than 31 nm/MPa/cm; the glass of the substrate has a distortion point of at least 710°C, an average thermal expansion coefficient at 30-350°C of 30×10-7 to 43×10-7/°C, a temperature T2 where the viscosity is 102 dPa/s of no more than 1710°C, and a temperature T4 at which the viscosity is 104 dPa/s of no more than 1320°C; the composition of the glass expressed as an oxide-basis molar percentage is SiO2: 66 to 70%, Al2O3 : 12 to 15%, B2O3: 0 to 1.5%, MgO: greater than 9.5 to 13%, CaO: 4 to 9%, SrO: 0.5 to 4.5%, BaO: 0 to 1%, and ZrO2: 0 to 2%; MgO+CaO+SrO+BaO is 17 to 21%; MgO/(MgO+CaO+SrO+BaO) is at least 0.40%, MgO/(MgO+CaO) is at least 0.40%; and MgO/(MgO+SrO) is at least 0.60. |
