Preparation and application of minerals-based sacrificial pastes for fabrication of LTCC structures

This work presents the preliminary results on application of mineral sacrificial layer that is prepared to structure LTCC (low temperature co-fired ceramic). The proposed method suggests utilization of a sacrificial paste, which remains "permanent" during firing and later removed by chemical dissolution, thus providing an effective support throughout the firing. The paste is based on a mixture of B2O3 and alkaline earth oxides and screen-printed on an LTCC sheet that is laminated with additional LTCC layers. B2O3 forms a consolidated structure by melting at low temperatures (400 °C) and wetting alkaline oxide with high melting temperature (>2000 °C), which can, after firing, be removed easily by chemicals. The basic characteristics that the pastes should possess can be summarized as: adequately formulated composition to allow easy etching, prevention of excessive reaction with the LTCC, matching shrinkage behaviour with LTCC. TGA (thermo gravimetric analysis), SDTA (single differential thermal analysis), XRD (X-ray diffraction) and SEM (scanning electron microscopy) will be the means of analysis to characterize the processed materials and fabricated structure, respectively.