Vibration assisted scribing process on LCD glass substrate

A technique of vibration assisted scribing of LCD glass substrate is developed. In the paper a fundamental theory of vibration assisted scribing process is manifested. It is proposed that the rapidly varying periodical scribing load does not lead to as much an increase in the plastic deformation as that due to the servo controlled constant scribing load. Instead it mainly results in an increase in the elastic deformation. The induced elastic component would increase the median crack depth of the glass substrate. To verify the proposed theory, an additional piezoelectric actuator is implemented on the servo controlled loading mechanism of the scribing machine, and a periodically varying load superposed on the constant load is provided to the standard scribing wheel. Experimental results show that under a proper vibration frequency condition the median crack depth is significantly increased to about twice of that without vibration assisted scribing. Thus, the automatic separation of the glass without the need of breaking process similar to the case with the use of toothed wheel (penett) can take place. On the other hand, while the bending strength of the glass panel after scribing by toothed wheel is merely about half of that resulting from scribing by standard wheel, it remains almost unchanged by the developed technique.