| 摘要 |
Disclosed is an alkali-free glass substrate wherein both the long side and the short side are not less than 1500 mm. This alkali-free glass substrate is characterized in that the difference between the maximum value and the minimum value of the absolute values of the thermal shrinkage rate of the substrate is not more than 5 ppm when the substrate is heated from room temperature at a rate of 10°C/min, kept at 450°C for 10 hours, and then cooled at a rate of 10°C/min (namely, when the substrate is heat-treated according to the temperature schedule shown in Fig. 1). Such a substrate can be produced by adjusting the average cooling rate within the range from the slow cooling point to the point lower than the slow cooling point by -100°C in the cooling process during production to not more than 100°C/min in the central portion and the end portion of the substrate in the width direction. |
