The Preparation And Performance Of Lithium Aluminun-silicon Glass-ceramics With Low Coefficient Of Thermal Expansion

With the rapid development of microelectronic technology, the electronic components are in the direction of miniaturization, multi-functional, integrated direction,which puts forward the intergration of circuit is more higher,which resulted in the higher of the electronic packaging materials.Due to its high flexural strength, low coefficient of thermal expansion, and good dielectric properties,Lithium-aluminum-silicon glass-ceramic has the potential as LTCC package . In this paper, we selected it as the research object, and explored the formulation and mechanism of Li₂O-Al₂O₃-SiO₂ to meet the requirements of LTCC packaging materials.In this paper, Li₂O-Al₂O₃-SiO₂ glass-ceramics were prepared by melting method.The effects of crystal nucleating agent and rare earth oxide doping on the crystal phase change, microstructure, flexural strength, thermal expansion coefficient and dielectric properties of the samples were studied. The results show that when the ZrO₂ + TiO₂ composite doped the same amount, the samples with higher ZrO₂ content have higher bending strength and better mechanical properties. The bending strength and thermal expansion coefficient of the samples can be promoted by the addition of La₂O₃ in lithium aluminum silicon glass .When the contents of La₂O₃ is 0.2wt%, the flexural strength is 163MPa, the thermal expansion coefficient is 2.64 × 10-6 /? ,.the comprehensive performance is the best. The addition of 1 wt%Sm₂O₃ in Li₂O-Al₂O₃-SiO₂ glass-ceramic has the lowest dielectric constant ?7.9? and dielectric loss ?1.23 × 10-3?, the highest bending strength ?162MPa?, the best performance,continue to increase the doping amount will deteriorate microstructure of the sampl and affect the performance of the sample. The Cr₂O₃ doped in the Li₂O-Al₂O₃-SiO₂ can significantly improve the microstructure and bending strength of the samples, and when the Cr₂O₃ doping amount is 3wt%, The sample has the most dense microstructure and the highest bending strength ?208MPa?, the best overall performance. Through the study of the doping modification of Li₂O-Al₂O₃-SiO₂ glass-ceramics, the performance of the samples was improved, and the LTCC packaging materials with excellent performance was obtained.In order to predict and control the thermal expansion coefficient of glass-ceramic samples, this paper draws on the existing thermal expansion coefficient calculation model, and puts forward the two kinds of calculation method of thermal expansion coefficients, the difference between the calculated value and the tested value is very large by the oxide method, this is because of the oxide method takes only the raw material of the glass-ceramic . The crystal phase method considered the residual glass phase and the crystal phases , The calculated values are in agreement with the tested values, and the error is less than 15%, which indicates that the thermal expansion coefficient can be adjusted by controlling the crystallization of the glass-ceramic.In this paper, the crystallization kinetics of Li₂O-Al₂O₃-SiO₂ glass-ceramic was studied. Kissinger analysis and Ozawa analysis were used to calculate the crystallization energy E of the samples. The results were similar. The crystallization index n was calculated by Ozawa analysis. The results show that the glass-ceramic in this experiment is the whole crystal.