A Research Of Low Temperature Cofired Ceramic Materials Of Mg-Al Based

With the rapid development of electronics,communications,aerospace and other industries,the development trend of electronic components is miniaturization,digitalization,integration and high speed.Electronic products are increasingly demanding on the performance and size of package substrates.Glass+ceramics for low temperature co-fired ceramics?LTCC?not only have low dielectric constant,low dielectric loss and low sintering temperature,but also can be used for high frequency communication??29?10GHz?.Therefore,it has been widely studied.In this paper,taking MgAl₂O₄ as the main ceramic phase and Li₂O-MgO-ZnO-B₂O₃-SiO₂?LMZBS?glass as the basic glass,the glass components,ceramic components,experimental process and modification of the glass+ceramics system were studied respectively.Firstly,the ceramic components were studied.In this section,the mixing ratio of glass and ceramics was optimized firstly.The experiment results showed that the increase of glass could accelerate the rearrangement of the particles and increase the density and the Qxf value,when the sintered body was not dense.In contrast,the Qxf value could be reduced because of the large amount of glass phase.Secondly,the effect of MgAl₂O₄ceramics synthesized from different raw materials on the microwave properties was investigated.Different raw materials have different particle sizes.And the smaller the particle sizes,the lower the activation energy,which promoted the grain growth and got a higher Qxf value.Then,in order to obtain LMZBS glass with the best Qxf value and three points flexural strength,the effects of B,Mg and Zn elements in the glass were researched systematically.The experiment results showed that the content of H₃BO₃ in glass system played a major role in the sintering temperature.When the H₃BO₃ content was lower than 40 wt.%,the sintering temperature was up to 1000°C.The possible reason is that when the content of H₃BO₃ was too low,there was a large amount of high melting point MgO phase.If the content of MgO in glass was too low or too high,the Qxf value would decrease,which depended on the non-intrinsic loss.For the former,the Qxf value was low because the second phase Mg₃B₂O₆ with better Qxf value was not synthesized.For the latter,there was decline in Qxf value as a result of the increase of the number of pores and the formation of liquid phases.In glass,ZnO could reduce the sintering temperature and affect the dielectric properties of glass+ceramics.With the increase of ZnO content,the formation of Mg₂B₂O₅ phases would be promoted,and Mg₃B₂O₆ and Li₂MgSiO₄ phases would be inhibited,which led to the decrease of the Qxf value.Finally,the experimental processes were investigated.The effects of calcining temperature on the dielectric properties and microstructure were studied.And then the effect of different ball milling time on the particle size distribution was discussed too.Through the above research on the glass ceramics system,the best microwave properties can be achieved for the glass+ceramics system sintered at 930°C:e_r=7.12,Qxf=48000?at 13GHz?,t_f=-70ppm/°C,flexural strength=203MPa.In order to make the materials properties meet the engineering applications requirements,thet_f was adjusted by adding SrTiO₃ into the glass+ceramics system.Thet_f of the glass+ceramics system was increased from-70 ppm/°C to+8 ppm/°C.