Crack Propagation Analysis in Laser Scribing of Glass

In the laser scribing of a glass sheet, a crack propagates across the glass surface as the surface is locally cooled down immediately following CO2 laser beam irradiation. In this process, the crack depth and scribable conditions are influenced by various parameters such as the laser power, the scribing velocity, and the distance between the heating area and the cooling area. Therefore it is important to examine the laser scribing phenomenon by analyses of these parameters. We analyzed the crack propagation phenomenon by a finite element method, using a two-dimensional model with a pre-crack. The crack depth was obtained by calculating the stress intensity factor. The obtained conclusions are as follows: The maximum velocity of the scribing for each laser power can be estimated by applying a static threshold of the stress intensity factor, K-Sth in the two-dimensional crack propagation analysis. The depth of the crack caused by the laser scribing can be estimated by applying a dynamic threshold of the stress intensity factor, K-Dth. As a result, the suitable scribing conditions for the practical use can be found. DOI:10.2961/jlmn.2010.02.0002