Patent ID: 8813520

Claim:
A method for manufacturing a glass substrate for a cover glass for protecting a display screen of a mobile terminal device, comprising the steps of: chemically strengthening the glass substrate by immersing the glass substrate in heated molten salt containing potassium nitrate such that ions of the glass substrate are ion exchanged for potassium ions of the molten salt at a temperature equal to or less than a glass transition point of the glass substrate; and removing 1 to 3 μm of an ion exchange layer formed in an uppermost surface layer of a primary surface of the glass substrate, by etching each surface of the glass substrate after the step of chemically strengthening; wherein a thickness of the glass substrate is 0.5 to 0.7 mm prior to the chemical strengthening step; and wherein the primary surface of the glass substrate has a potassium ion concentration equal to or less than 5000 parts per million (ppm) after the 1 to 3 μm of the ion exchange layer is removed.