Yun Chuan Liu,Li Ying Zhang,Xiang Lei Yu,Wei Chao Li,Jun Peng Li,Guo You Gan
A high-temperature conductive silver slurry containing lead-free ZnO-B2O3-SiO2 glass for metallization of ceramic MgTiO3 substrate has been prepared. The ZnO-B2O3-SiO2 glass was obtained by high-temperature melting and cold extraction with a transition temperature (Tg) of 579 °C and thermal stability (∆T) of 105 °C as an inorganic bonding phase of high-temperature conductive silver paste. Then, silver paste with different glass powder content was sintered on ceramic MgTiO3 substrate between 730 °C and 930 °C in increments of 50 °C. Characterization of the prepared materials revealed that their resistivity increases with the increase in glass powder content and decreases with the increase in sintering temperature. Sintering temperature and glass content have significant effects on the resistivity and adhesion of the thick silver film. When the silver paste with a glass content of 1.1 wt% was sintered at 830 °C for 10 min, the resulting thick silver film had a low resistivity of 1.81 μΩ·cm (1.65 μΩ·cm for silver) and a good adhesive strength of 39.4 N mm−2. During the sintering process, the glass material melts and wets the silver powder, which promotes the sintering of the silver powder to form a dense network structure and improves the electrical conductivity of the silver film. In addition, the formation of ZnTiO3 by chemical reactions between the glass and the substrate was observed, which dramatically improved the bonding strength of the silver film. Therefore, lead-free silver paste containing ZnO-B2O3-SiO2 glass powder and MgTiO3 ceramics has broad development prospects in ceramic filters.
Bo Wang,Zihao Pan,Ziyan Zhao,Bo Zhou,Xuejian Liu,Zhengren Huang,Yan Liu
In this paper, we designed two series of the ZnO-B 2 O 3 -SiO 2 (ZBS) glass to explore their applicability for joining AlN ceramic. The density, flexural strength, structure, characteristic temperature, coefficient of thermal expansion (CTE) and crystallization behavior of the ZBS glass with varying ZnO and B 2 O 3 content were systematically studied. The results show that as B 2 O 3 content increase, the glass network is disrupted with the transition from three-dimensional shelf-like structure [BO 4 ] to two-dimensional layers [BO 3 ], increasing the number of the broken bonds, while an increase in ZnO results in a more compact glass network structure. We also found that both glass transition temperature (T g ) and softening temperature (T S ) exhibit a declining trend with the increase in B 2 O 3 and ZnO. Zn 2 SiO 4 and ZnAl 2 O 4 , began to precipitate after heat treatments in all the samples except 60ZnO-30B 2 O 3 –10SiO 2 (abbreviated as B30), where the diffraction peaks do not appear in Zn 2 SiO 4 but in Zn 4 B 6 O 13 . Notably, Zn 2 SiO 4 is the main phase for most samples while the main phase of B30 sample is ZnAl 2 O 4 . The CTE increases from 4.6 to 5.03 (× 10 –6 / °C) and 4.23 to 4.73 (× 10 –6 / °C) with an increase of B 2 O 3 and ZnO content, respectively. Among these, the CTE of B30 sample is compatible with that of AlN ceramic substrate. The optimal shear strength, 60.32±10.26 MPa, was achieved with B30 samples at 750 °C. The high strength was attributed to the interfacial reaction that leads to strong chemical bonding and the uniform distribution of the ZnAl 2 O 4 in the interlayer, which reinforces the strength of the interlayer itself.
A new type of glass/ Al 2 O 3 ceramic composite material was prepared by the conventional solid-state method for lead-free low-softening ZnO-B 2 O 3 -SiO 2 (ZBS) glass. The effects of glass content and sintering temperature on the phase structure, sintering performance, microstructure, dielectric properties, thermal properties and mechanical properties of the composite materials were investigated by adding different mass fractions of ZnO-B 2 O 3 -SiO 2 glass into Al 2 O 3 ceramics. The results show that the doped ZnO-B 2 O 3 -SiO 2 glass effectively reduced the sintering temperature of Al 2 O 3 ceramics, and the sintering aid ZnO-B 2 O 3 -SiO 2 glass had no crystalline phase. The ZBS/ Al 2 O 3 composites sintered at 875–925 ℃ mainly contain two crystalline phases, ZnAl 2 O 4 and Zn 2 SiO 4 , and the content of the phases depended on the composition of the composites and the sintering temperature. When the content of ZnO-B 2 O 3 -SiO 2 glass was 74 wt.%, and the composites were sintered at 875 ℃ for 1 h, the volume density of the composites was 3.49 g/cm 3 , the thermal conductivity λ was 1.46W/mK, the thermal expansion coefficient CTE was 5.52/ppm ℃, the flexural strength was 155 MPa, the relative dielectric constant was 6.28, and the dielectric loss was 0.937 × 10 −3 (@12.571 GHz). The dielectric properties are the best, and it has a good application prospect in LTCC at high frequencies.
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