Study On Preparation And Properties Of Calcium Aluminosilicate Oxyfluorine Glass/ceramic LTCC Materials

Low temperature co-fired ceramic（LTCC）materials are a very important part of electronic packaging technology and a relatively complex process.LTCC materials have a very important impact on the performance,quality and selection of related process materials of electronic packaging modules,while glass/ceramics composite materials have become the mainstream LTCC substrate materials because of their many systems and controllable performance.In this paper,calcium aluminosilicate oxyfluoride（CFAS）glass/ceramic composite materials are selected as the research object.Based on CFAS glass,corundum and quartz were used as ceramic fillers to prepare LTCC substrate materials,and the microstructure and properties of the composites were optimized by changing the content of CaF₂ and Al₂O₃in CFAS glass.In the experiment,high-temperature melting method was used to prepare CFAS glass.The crystal phase composition and microstructure of the sample were analyzed by X-ray diffraction analyzer and scanning electron microscope（SEM）.The mechanical strength of the sample was tested by three-point bending method.Impedance analyzer to collect the dielectric constant and dielectric loss data of the sample.The experimental results show that CFAS glass has good wettability to corundum filler.When the content of corundum reaches 30 wt.%of the composite material and the sintering temperature of the sample is 850℃,A small amount of calcium feldspar（CaAl₂Si₂O₈）precipitated in the material.The bulk density and bending strength of the composite materials both reached maximum values of 2.89 g/cm³ and 290 MPa,respectively.The thermal expansion coefficient is 5.08×10^-6/℃（20-500℃）,which is close to the thermal expansion coefficient of silicon chips.And at this time,the optimal combination of dielectric properties is achieved,and the dielectric constant and dielectric loss are 3.13 and 2.45×10^-3（1 MHz）,respectively.When quartz is used as the ceramic filler,the good sintering temperature of the composite material can be reduced to 830℃.However,compared with CFAS glass/corundum composites,the bending strength is reduced and the thermal expansion coefficient is too large,which is 10.27×10^-6/℃（20-500℃）,which is difficult to match the thermal expansion coefficient of silicon chips.In addition,CFAS glass has poor wettability to quartz particles,causing serious deterioration of its dielectric loss.The increase of CaF₂ content in CFAS glass components will reduce the optimal sintering temperature of the composite material.And with the increase of CaF₂ content,the bulk density and flexural strength of the composites show a trend of first decrease,then increase and then decrease,and the thermal expansion coefficient gradually increases with the increase of CaF₂ content,and the dielectric properties do not change much.As the proportion of Al₂O₃ in the glass component increases,the bending strength of the composite material does not reach the expected improvement effect,and the maximum value is only 245 MPa.And the increase of the content of Al₂O₃ will increase the dielectric constant and dielectric loss of the sample in the optimal compact state,which are 4.92 and 2.63×10^-3（1 MHz）,respectively.However,the stability of the dielectric properties of the composites at high frequencies has not been affected by the increase in Al₂O₃ content.