Precision glass machining, drilling and profile cutting by short pulse lasers

Demands for producing micro-crack free, high quality and high-aspect ratio microholes and microfeatures in glass substrates have been increasing for a number of applications such as in MEMS device packaging, optical fibre alignment, mini-vision systems and microelectronic packaging. However, due to the poor thermal properties of most glasses the fabrication of finely machined features, e.g. grooves, microholes etc. has been a challenging task. In this study, short pulse solid-state lasers with pulse duration in the ns to fs range were used to process different types of glass materials. The effect of the pulse duration and other process parameters on the machined features was analyzed to reveal the underlying thermal effects and nonlinear processes. Edge quality, circularity, aspect ratio, formation of the redeposit material and machining rate were also studied with respect to the process variables such as focusing optics, laser power, wavelength and repetition rate. Arrays of drilled micro-hole patterns and fabricated microfeatures are demonstrated with discussions on their potential applications.