Research On Li-Al-Si Ceramic Materials With High Thermal Conductivity

With the miniaturization,integration and high density of electronic equipment,the energy density of devices is getting bigger and bigger,which needs the substrate materials with higher thermal property.Currently,the research on ceramic with high thermal conductivity is mainly focused on doping of ceramics such as AlN and Al₂O₃,but they require a high sintering temperature?1600?¹800??,which greatly limits these high thermal conductivity materials in the LTCC field?sintering temperature below 950??.Therefore,it is particularly important to prepare LTCC with excellent thermal conductivity.Due to the outstanding thermal and dielectric performances of Li-Al-Si?LAS?,in this paper,the LAS-based LTCC substrate materials are prepared by traditional solid-state method.Meanwhile,the effects of raw composition and experimental process on the properties of ceramic are discussed.Further,K₂O-B₂O₃-SiO₂?KBS?and BaO-MgO-SiO₂?BMS?glass are doped in LAS ceramics to reduce the sintering temperature,respectively.Correspondingly,the influences of glass types and contents on the composition,microstructure,and performance of composites are studied.Firstly,the composition,microstructure,and comprehensive properties of ceramics using Al₂O₃ and AlN as raw materials are examined,respectively.The research shows ceramics prepared from Al₂O₃ have better comprehensive properties than those prepared from AlN.Adequate Al₂O₃ can improve the microstructure and promote the performance of ceramics.When the quality radio of Al₂O₃ is 4%and sintering temperature is 1020?,LAS ceramics have excellent properties:thermal conductivity is 10.46W/?7?m?K?8?,flexural strength is 180.23 MPa,dielectric constant is 6.51.Secondly,the influences of the technological process and Si/Li ratio in the raw materials on ceramics are examined.The consequences show that the appropriate pre-firing temperature is conducive to the initial reaction between the oxides and accelerates the densification and sintering process of the materials.The optimal molar ratio of Si/Li is 0.55.Finally,in order to reduce the sintering temperature of LAS ceramics,KBS and BMS glass are doped respectively,and the influence of glass content on the sintering behavior and performance are discussed.As a result,the addition of two kinds of glass can effectively reduce the sintering temperature of LAS.Compared with BMS,the KBS can get better achievement in lowing sintering temperature,and the thermal conductivity and flexural strength of KBS/LAS composites are higher.When the sintering temperature of KBS/LAS is 900?and the content of KBS is 2%,the composites have the best performance:thermal conductivity?9.83W/?7?m?K?8??,flexural strength?215.09 MPa?,and dielectric constant?6.24?.