The Study Of Preparation And Properties Of LTCC Materials Based On Li₂MgSiO₄

With the microwave communication field developed rapidly,and more attention are paid to electronic components due to the requirements for miniaturization,high integration and multifunctionalization.LTCC technology has risen rapidly in the field of microelectronics for several years.LTCC materials need lower sintering temperature（<960℃）,suitable dielectric constant,higher Q?f value and near zero temperature coefficient,meanwhile good chemical compatibility is required when co-fired with electrode materials.Li₂MgSiO₄ ceramics as the main research object are studied via solid-phase synthesis in this paper.The microwave dielectric properties of Li₂MgSiO₄ ceramics and different glass to reduce the sintering temperature of Li₂MgSiO₄ ceramics are investigated in detail.In addition,TiO₂ is used to adjust the temperature coefficient of Li₂MgSiO₄ ceramics after low-sintered.As the specific research contents follows:1.The Li₂MgSiO₄ ceramics was prepared by solid-phase synthesis,and the calcination temperature of Li₂MgSiO₄ powder was discussed via differential thermal analysis.The phases of the powder at different calcination temperatures were compared by XRD analysis.When Li₂MgSiO₄ powder calcinated at 800℃,there was a little unreacted MgO and SiO₂ in the powder,and the second phase Li₂SiO₃ was detected;with the calcination temperature increased,MgO and SiO₂ decreased,while the second phase Li₂SiO₃ increased.When Li₂MgSiO₄ ceramics calcinated at 850℃and sintered at 1250℃for 2 hours,the following microwave dielectric properties were obtained:?_r=6.08,Q?f=31872GHz,?_f=-76.5 ppm/℃.2.To achieve the low-temperature sintering of Li₂MgSiO₄ ceramics,several different glass La₂O₃-B₂O₃-ZnO（LBZ）,Li₂O-Al₂O₃-B₂O₃（LAB）and ZnO-B₂O₃-SiO₂（ZBS）as the sintering aid were studied to low the sintering temperature of Li₂MgSiO₄ ceramics.As the related research contents follows:（1）The addition of 0.5wt%².0wt%La₂O₃-B₂O₃-ZnO（LBZ）glass can effectively reduce the sintering temperature of Li₂MgSiO₄ ceramics to around 900℃,XRD analysis showed that with the amount of LBZ glass increased,second phase of Mg₂SiO₄ and a trace of unreacted SiO₂ were detected,and the rest were the main crystal phase Li₂MgSiO₄.When adding 1.0wt%LBZ glass and sintered at 900℃,good microwave dielectric properties of Li₂MgSiO₄ ceramics were achieved:?_r=6.01,Q?f=28507GHz,?_f=-29.84 ppm/℃;（2）After adding 0.25wt%-1.0wt%Li₂O-Al₂O₃-B₂O₃（LAB）glass,Li₂MgSiO₄ceramics can be sintered at 925℃to obtain better bulk density.After XRD analysis,it was known that the main crystal phase of the sample was Li₂MgSiO₄.No second phase was detected in the system when LAB glass addition increased.The following microwave dielectric properties of the Li₂MgSiO₄ ceramics added with 0.5wt%LAB glass sintered at 925℃were achieved:?_r=6.2,Q?f=33368GHz,?_f=-64.3 ppm/℃;（3）The sintering temperature of Li₂MgSiO₄ ceramics was reduced from 1250℃to925℃by adding ZnO-B₂O₃-SiO₂（ZBS）glass.According to XRD analysis,no second phase was detected in the sample,indicating that the sample was Li₂MgSiO₄ single-phase ceramic material.When the Li₂MgSiO₄ ceramics added with 1.0wt%ZBS glass sintered at 925℃,the following microwave dielectric properties were obtained:?_r=6.13,Q?f=31992GHz,=-79.6 ppm/℃.3.Li₂MgSiO₄-1.0wt%LBZ ceramics doped with TiO₂ to adjust its temperature coefficient.It was found that TiO₂ can effectively adjust the value of Li₂MgSiO₄-1.0wt%LBZ ceramics;however,the Q?f value decreased obviously with the dielectric constant increased.According to XRD analysis,with the content of TiO₂increased,the second phase Li₂TiO₃,Li₂TiSiO₅ and Mg₂SiO₄ were detected in the system,which influenced on the microwave dielectric properties of the ceramics.As the sample doped with 20wt%TiO₂ sintered at 930℃,its temperature coefficient had a smaller value:?_r=7.51,Q?f=12019GHz,?_f=-16.14 ppm/℃.