Selective laser heat treatments for melting and crystallization of glass

This research investigated the behavior under selective laser remelting / devitrification of a parent glass powder of Sr2TiSi2O8 based glass ceramic. The purpose is to determine suitable conditions to form dense Sr2TiSi2O8 thin components usable in hybrid circuits for piezoelectric applications. Powder compacts have been treated in order to characterize the response of the powder according to the laser scan conditions (power, spot speed and vectorization step of the scan lines). The structure of the surface after selective laser treatment by a Nd-YVO4 (20W / 40 µm spot size / cw mode) have been evaluated by X-ray diffraction, scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). Results show that suitable scanning conditions make possible to obtain a dense and homogeneous glass coating. Devitrification of the amorphous coating may be realized with precise laser parameters. Moreover, the XRD patterns and the SEM observations highlight that the coating is fully crystallized with Sr2TiSi2O8 crystals correctly oriented. In order to investigate a specimen configuration similar to microelectronic components, next step is to realize a coating (typically 20 µm thick) on a substrate. First we will investigate a process to realize a coat of glass powder an alumina substrate. Then laser parameters have to be optimized for remelting and devitrification of the coating. Last step will be the characterization of the coating's electrical properties.