Preparation And Properties Of Borosilicate/AlN Composite For Low Temperature Co-fired Ceramics Application

In this paper, the preparation and properties of glass/AlN composites for LTCC(low temperature co-fired ceramics) application were studied. In order to densify thecomposites at low temperature and in normal pressure, CBS(CaO-B2O3-SiO2) glassand multi-component borosilicate glass were firstly designed, and then compositedthe prepared glass with AlN powder. Several methods such as XRD, SEM were usedto study the sintering property, phase composition and microstructure of thecomposites. Effects of glass composition, sintering temperature and AlN content onthe properties of the materials were analyzed in detail.First, the components of calcium borosilicate glass were designed according toCaO-B2O3-SiO2phase diagram. On the basis of the sintering property and phasecomposition, CBS glass can densify at850℃and crystallized into CaB2O4and quartzafter sintering. The sintering ability of CBS/AlN composites was poor as the CBSglass cannot wet AlN and the AlN itself owns a low diffusion coefficient.Second, in order to obtain the glass with low melting temperature and wellwetting ability on AlN ceramic, BaO, Al2O3, Li2O and ZnO were added into CBSglass. The results showed that sintering temperature decreased with the increase inglass content, and the samples densified when the glass content was higher than40wt%. The main crystalline phases of the composites were celsian (BaAl2Si2O8) andAlN. According to the sintering properties of the composites, non-reactive liquidphase sintering was considered to be the dominant mechanism in this material system.Last, the thermal conductivity, TEC(thermal expansion coefficient), dielectricconstant, dielectric loss and flexural strength of samples were studied. Results showedthat porosity degraded the performances of the materials sharply. As for thewell-densified samples, the increase in AlN content directly improved theperformances of the composites. Composite with good comprehensive properties wereobtained as the AlN content was40wt%.