A new evaluation method of the "Edge Impact Test" has been developed. Breakage of cover glass from the edge is enabled to evaluate quantitatively by this method. It is found that resistance to edge impact damage has a correlation with the CT of glass, and a high CS is more effective to improve resistance to the edge impact damage than deep DOL.

Newly developed stress profile of chemically strengthened glass for smartphone cover glass is demonstrated in this study. This innovative stress profile, named as EICS profile, improves the durability to the drop breakage. With this EICS profile, high strength cover glass, such as the glass, which is 2 times or more stronger than ever to the rough ground, can be obtained.

This paper proposes a new process to manufacture cover glass which overcomes a strength trade‐off between the face and the edge. In the process, alkali‐barrier films are deposited on glass faces before an ion‐exchange process in order to control face stress properties without inhibiting the edge strengthening. As a demonstration of the process, alkali‐alumino‐silicate glass sheets with SiO2 films were chemically strengthened, and their stress properties and strengths were investigated. As a result, thicker SiO2 films cause lower face DOL (Depth Of strengthened Layer), and it is observed that the faces have lower DOL than the edges. In strength tests corresponding to major fracture modes of smartphone cover glass, specimens with 80‐100 nm films have more balanced face performance and better edge impact strengths than the no‐film specimen.

This paper proposes a new process to manufacture cover glass which overcomes a strength trade-off between the face and the edge. In the process, alkali-barrier films are deposited on glass faces before an ion-exchange process in order to control face stress properties without inhibiting the edge strengthening. As a demonstration of the process, alkali-alumino-silicate glass sheets with SiO 2 films were chemically strengthened, and their stress properties and strengths were investigated. As a result, thicker SiO 2 films cause lower face DOL (Depth Of strengthened Layer), and it is observed that the faces have lower DOL than the edges. In strength tests corresponding to major fracture modes of smartphone cover glass, specimens with 80-100 nm films have more balanced face performance and better edge impact strengths than the no-film specimen.