| Recently, the main trends of electronic devices and components are to realize the chip device, small size, and higher integration of different functionality with the development of science and technology and the demands of customers. Realizing the chip device is the base of small size and higher integration of different functionality, low-temperature cofired ceramics (LTCCs) are receiving increasing attention in the research community because the application of novel chips multilayer structure involving small size and the integration of passive components. In multilayer structure, it is necessary to lower the sintering temperature of the dielectrics in order to co-fire with low melting point and highly conductive internal electrode metals, such as silver, copper, and their alloys. The key issue of manufacturing chip devises, such as chip LC filters, is cofiring the capacitors and inductors together at low temperature. In present investigation, the ZnTiO3 system dielectric materials and NiZnCu ferrite materials were selected as investigative object. Firstly the low-temperature sintering behavior and improvement of properties by dopants of dielectric materials were investigated, then by using zero-shrinkage technique, zero-shrinkage-difference technique, and adding interlayer, the low-temperature (≤900℃) co fired compositions with no camber, deformation and cracks were prepared. The interfacial diffuse, interfacial reactions, shrinkage behavior and dielectric properties of cofired compositions were researched.Zinc titanate ceramics were prepared by conventional mixed-oxide method combined with a chemical processing. The influences of raw materials on the low-temperature sintering of ceramics and the effects of V2O5, WO3 and V2O5-B2O3 addition on the phase stability, microstructures and low-temperature sintering behavior of ZnTiO3 ceramics were investigated. The results show that the low-temperature sintering of ceramics were very sensitive to raw materials, especially for TiO2. The densification temperature of ZnTiO3 ceramics could be reduced to 900℃by adding the above addition. The low-temperature sintering mechanism of V2O5-doped and V2O5-B2O3-doped zinc titanates ceramics was liquid phase sintering mechanism, while low-temperature sintering of WO3-doped zinc titanates ceramics can be attributed to solid phase reactive sintering mechanism. V2O5-doped zinc titanates ceramics exhibit the properties: Qxf=8061GHz,εr=21.3.The replacement of Zn by Mg enhances the thermal stability and extends the stability range of hexagonal phase. The densification temperature of (Zn, Mg)TiO3 (abbreviated as ZMT) ceramics can be reduced from 1200～1300℃to below 900℃by the chemical processing combined V2O5 additions. V2O5-doped ZMT ceramics exhibit good dielectric properties,εr=22 and tanδ=5.7×l0-4 for ZMT ceramics sintered at 875℃. The substituting Sn for Ti accelerated the decomposition of hexagonal phase, and cubic spinel Zn2(Ti1-xSnx)O4 solid solution formed. 1 wt% of V2O5 and B2O3 with the mole ratios of 3:1 were used to lower the sintering temperature of ceramics from 1300℃to 1000℃, The best dielectric properties were obtained at x=0.3. TheZnO-0.7TiO2-0.3SnO2 ceramics sintered at 900℃exhibit the dielectric properties:εr=29, tanδ=9.86×10-5.The tolerance factor computing formula of ilmenite structure was proposed for the first time, and the formula was proved appropriate for ilmenite structure by analyzing the structure stability of some ilmenite compounds, such as MgTiO3, NiTiO3, CoTiO3, ZnTiO3, and complex ilmenite (Zn1-x, Mx)TiO3 (M denote Mg, Ni, Co). According to the results of statistical analyzing the tolerance factor and electronegativity difference of the present ABO3-type ilmenite, the experience tolerance factor value and experience electronegativity difference value to form stable ilmenite compound were obtained, that is, t>0.80, e>1.465。ZT/NZC low-temperature co-sintered layer samples with no delamination, camber and crack defects were successful prepared using wet pulling film technics (a manual wet tape cast technique). The interfacial diffuse and interfacial reactions form and were studied.The sintering kinetics of ZMT3 ((Zn0.7Mg0.3)TiO3) and NZC were investigated, and the shrinkage kinetics equation was proposed. It is proved that the formation of camber results from the shrinkage difference of two materials in the sintering final stage. The geometric equation of camber was proposed to characterize the development of the camber. It is concluded that the more the shrinkage mismatch is, the larger the camber is. In addition, the experimental results indicate that the molding press has a great effect on the shrinkage of samples. By changing the molding press, the shrinkage difference and camber of co-sintered ZMT3/NZC samples can be weakened.The HH2 (mixing powder of ZMT1 and NZC in weight ratio 1: 1) and ZMT1 were selected as interlayer to relax the interfacial stress resulting from the shrinkage difference. The ZMT3/ZMT1/NZC and ZMT3/HH2/NZC co-sintered samples without delamination, camber and crack defects were prepared by dry press molding. The interfacial diffusion present in all interfaces of co-sintered samples. The semi-infinite diffusion couple model was used to fit the interfacial diffusion behavior, and the fitting results are consistent with the experimental results. According to this model, the diffusion coefficient and diffusion activation energy of different ions were estimated. The sequence of the ionic diffusion coefficients (900℃) and diffusion activation energy are as follow: D (Zn2+)＞D (Ni2+)＞D(Ti4+)＞D (Fe3+) and Qd (Fe3+)＞Qd (Ti4+)＞Qd (Ni2+)＞Qd (Zn2+), respectively. In addition, it is found that the ionic diffusion coefficient varied with different diffusion couple and sintering temperature.The zero shrinkage difference model of sandwich layer structure was founded according to our proposing zero shrinkage difference technology. Using this technology, the ZMT3/NZC/ZMT3 and NZC/ZMT3/NZC co-sintered sandwich layer samples without delamination, camber and crack defects were prepared. The experimental results reveal that using ZMT3 with bigger shrinkage than NZC as interlayer materials can eliminate the cracks effectively. The density correct factor k was proposed to characterize the difference between experimental density and fitting density. When k=0, it implies that there is no interfacial diffusion. The interfacial diffusion will result in interfacial density decrease.The dielectric properties of different co-sintered layer composition samples were investigated. The results show that sandwich layer samples have lower dielectric loss and dielectric constant than ZT/NZC, ZMT3/NZC/ZMT3 and NZC/ZMT3/ NZC samples.
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