Development of a Crack Cutting Method for Glass Plates Used for Flat Panel Displays

摘要

With a purpose to develop a new breaking method for brittle materials with high precision and high accuracy, indentation of glass surface using an inclined pyramid type indenter is proposed. It was reported that for an indentation angle of θ_i=3°, crack occurs straight in the inclination direction along the diagonal corners of the indent even for a single indent, and the probability of occurrence of the crack is rather high even for low loading. In this paper, a study on the crack occurrence mechanism, an analysis of the distribution of various stress, strain and hydrostatic pressure along with 3D FEM analysis using ductile fracture criteria is performed. As a result of this analysis, the fracture coefficient (C value) distribution, the qualitative measurement of crack propagation as well as propagation position of the indentation by a single pyramid indenter has been obtained. Intermittent indentation using an indenter with an indentation angle of θ_i=3° at a uniform interval of d=30μm along the ridge direction was performed. As a result connection between adjacent cracks along the diagonal could be achieved. On breaking the glass panel along a direction parallel to the diagonal crack direction, a good surface could be obtained. Finally a prototype inclined pyramid indenter type scribing machine based on the research results was manufactured and was found to work satisfactorily.