Study On Microwave Dielectric Properties Of Low Temperature Co-fired Ceramics For Mg₂Al₄Si₅O₁₈-TiO₂-BBS System

Low Temperature Cofired Ceramics?LTCC?technology is a new material technology that is the technical basis for high integration,high performance electronic packaging and miniaturization,light weight and high reliability of electronic components.Nowadays,low temperature co-fired ceramic materials are mainly divided into two categories: 1)pure glass ceramic system,2)composite system of ceramic material and glass ceramic.Firstly,the temperature coefficient of cordierite is adjusted by TiO₂.After obtaining the ratio of TiO₂ with a temperature coefficient close to zero.By means of XRD,SEM,EDS,DSC,vector network analysis,impedance analysis and other methods are used to study the addition of different crystal nucleating agents and different contents of low melting glass powder to the material effect on microwave dielectric properties.The main contents of this article are as follows:?1?Studying a series of?1-x?Mg₂Al₄Si₅O₁₈-TiO₂-x TiO₂?x=0.05,0.1,0.15,0.2,0.25,0.3,0.35?ceramics.When 0.05?x?0.1,no rutile phase was detected by XRD test,indicating that TiO₂ and cordierite formed a solid solution.When 0.15?x?0.35,many white spots appeared on the surface of the crystal grains.The EDS test indicated that the white point belongs to TiO₂.When x=0.1,The ceramic obtains the highest Q×f values,and the microwave dielectric properties are: ?r = 6.2,Q×f = 68756 GHz,tf =–25 ppm/°C,when x=0.25,the temperature coefficient of resonant frequency close to zero is obtained,the microwave dielectric properties at this time are: ?r = 6.7,Q×f =51186 GHz,tf = –1.2 ppm /°C.?2?The sintering mechanism,microwave dielectric properties,microstructure,phase composition and influencing factors of BBS?Bi₂O₃-B₂O₃-Si₂O₃?glass and Mg₂Al₄Si₅O₁₈-TiO₂ ceramic composites with TiO₂ were studied systematically.During the sintering process,there was no chemical reaction between the(0.75Mg₂Al₄Si₅O₁₈-TiO₂-0.25 TiO₂)ceramic and the BBS glass.From the XRD analysis,only the Mg₂Al₄Si₅O₁₈-TiO₂ phase and the TiO₂ phase were present,and the BBS addition amount was 6wt%,0.75Mg₂Al₄Si₅O₁₈-TiO₂-0.25 TiO₂ addition amount was 94wt% by weight of the composition was co-fired with Ag at 925°C for 4h.XRD analysis showed that the composite did not react with Ag.As the BBS glass content increasedfrom 4wt% to 12wt%,the dielectric constant of BBS/0.75Mg₂Al₄Si₅O₁₈-TiO₂-0.25 TiO₂increased from 4.3 to 5.5,the Q×f values increased from 5500 GHz to 26900 GHz,and the temperature coefficient was from-9.5ppm/°C reduced to-11 ppm/°C.When the content of BBS glass added was 6wt%,0.75Mg₂Al₄Si₅O₁₈-TiO₂-0.25 TiO₂ was 94wt%,the composite sintered at 1025°C for 4h showed the best microwave dielectric properties:?r = 5.4,Q×f = 26900GHz?at 16.02 GHz?,tf=–9ppm/°C.?3?The sintering mechanism of MAST and MASTL glass-ceramics was prepared and studied by high-temperature melting method.The microwave dielectric properties of MAST and MASTL glass-ceramics were characterized.The sintering process is mainly composed of two parts,that is,the samples in the previous stage are nucleated at 780°C for 2h,and the crystallization process at 850°C?1250°C for 2h,By means of XRD and DSC,the crystallization process of MAST and MASTL glass-ceramics were studied.when sintered at 1200°C for 2h,MAST glass ceramics obtains the best microwave dielectric properties: ?r = 8.2,Q×f =17574 GHz?at 11.8GHz?,tf =–23.8ppm/°C.When the sintering temperature is 1150°C for 2h,MASTL glass ceramics obtains the best dielectric properties: ?r=8.4,Q×f =16596 GHz?at 12.28GHz?,tf =–17.6ppm /°C.