In the field of electronics industry, alumina substrate has become an indispensable base material for electronic components because of its excellent insulation, chemical stability, high thermal conductivity and good high-frequency performance. It not only plays the role of support and heat dissipation, but also ensures the insulation performance of electronic components. Alumina casting slurry is the key raw material for the preparation of alumina ceramic substrate, and its composition and characteristics directly determine the quality and performance of the final product. The purpose of this article is to investigate how the characteristics of alumina powder, including purity, size and specific surface area, morphology and dispersion, affect the casting process and the performance of alumina ceramic substrate.

 

 

Purity effect

The purity of alumina powder is the basis of casting slurry quality. The required alumina content is usually not less than 95% to avoid the negative impact of impurities on the appearance, shrinkage, microstructure and performance of the finished product. For example, aluminum oxide powders containing free Fe particles will lead to color development inside or on the surface of the ceramic during the sintering process, forming spots that not only affect the appearance, but also reduce the insulation performance.

 

The effect of powder size and specific surface area

The size of the alumina powder is controlled in the range of 0.3-1.7μm, and the specific surface area is between 2-11m²/g, which has an important impact on the density of the finished product. Small particle size powder has higher surface area and surface energy, which is conducive to the densification of casting film. However, too small particle size will increase the need for additives such as dispersants and binders, deteriorate slurry fluidity, increase sintering shrinkage, and reduce sintering density.

 

Effect of powder morphology

The morphology of alumina powder is various, including spherical, flake, fibrous and irregular. Because of its smooth surface and good fluidity, the spherical particles are conducive to improving the density of the finished product. In contrast, non-spherical particles are easy to form gaps after sintering, which affects the densification process.

 

Optimization of decentralization

Improving the dispersion of the powder in the slurry is the key to ensure the quality of the finished product. In addition to the addition of dispersants, the powder surface modification treatment, such as chemical modification or physical treatment, can significantly improve the dispersion and rheological properties of the slurry, so as to optimize the casting process.

 

In summary, the characteristics of alumina powder play a crucial role in the casting process of alumina ceramic substrate preparation. By strictly controlling the purity, size, surface area and morphology of the powder and optimizing the dispersion, the key performance indicators such as thermal conductivity, resistivity, dielectric constant, chemical stability and mechanical strength of the alumina ceramic substrate can be significantly improved. In the future, with the continuous progress of material science and preparation technology, the in-depth study and fine regulation of the characteristics of alumina powder will further promote the application and development of alumina ceramic substrates in the field of high-end electronic components, and provide a solid foundation for the sustainable development of the electronics industry.