Patent ID: 8642175

Claim:
A glass substrate usable for a cover glass of a mobile terminal device to protect a display screen of the mobile terminal device, comprising: a primary surface comprising: a compressive stress layer formed in an uppermost surface layer thereof by chemical strengthening; wherein the compressive stress layer contains one or more potassium ions; and wherein the compressive stress layer is configured to enhance strength of the glass substrate due to a compressive stress generated in the compressive stress layer; wherein the primary surface is an etched face; and wherein the compressive stress layer consists of a layer of a potassium ion concentration more than 0 parts per million and equal to or less than 5000 parts per million; and wherein the glass substrate has a breaking load equal to or greater than 546 N, the breaking load being measured when a center of the primary surface of the glass substrate, which has a thickness of 0.5 mm, is pressed with a pressing pin in a state where a peripheral end of the glass substrate is held.