Study On The Application Of Spodumene Crystallizable Glass For LTCC Composites

In this paper, the primary aim is to prepare low-TCE composites for LTCCapplication with spodumene crystallizable glass. In this paper, we tried to prepare“glass+ceramic” system LTCC material by the mixture of spodumene crystallizableglass and fused silica, and “glass+glass” system LTCC material by the mixture ofspodumene crystallizable glass and anorthite crystallizable glass.Three kinds of spodumene glasses whose mole ratios of Li:Al:Si were1:1:3.5,1:1:4and1:1:6respectively were designed. The sintering character of the spodumeneglasses was studied. The results indicated that the sintering process was inhibited bythe crystallization. So the sintering ability of all the “spodumene glass+fused silica”composites was poor. When it came to the “spodumene glass+anorthite glass”composites, although the sintering ability of the pure glasses was poor, the densifiedcomposites were achieved.The difference in phase evolution between two pure glasses and the compositeswas shown in the XRD results. The main phases of the composites were β-quartz solidsolution （or β-spodumene solid solution depending on the sintering temperature）derived from LASB glass and anorthite derived from CMABS glass respectively.Diopside crystallized in the composites above840°C, indicating that mutual diffusiontook place between the glasses during sintering. As a consequence of the mutualdiffusion, alkaline earth ions partially occupied the sites for the motion of the Li+inthe glass and the dielectric loss of the composite was below0.005. The DSC resultsproved that the sintering mechanism of the pure glasses was viscous flow sintering.Densification process of the composites was a two-stage viscous flow sinteringprocess, which was dominated by LASB glass and CMABS glass in sequence.Densified composites （relative density>95%） were obtained from800°C⁸80°C.CTE of the measured composites was in the range of2.8⁵.4×10^-6K^-1and could beadjusted by simply changing the ratio of LASB/CMABS. Dielectric constant values ofthe studied composites sintered above840°C were between5.2and5.8. The preparedcomposites have the potential for LTCC application.