Novel process for cover glass with ideal stress distribution

Abstract — This paper proposes a new process to manufacture cover glass that 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 sputter‐deposited SiO₂ films were chemically strengthened, and then 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.