Black porous alumina ceramics: The light-absorbing material of semiconductor vacuum ceramic chuck
In recent years, with the continuous improvement of the product performance and output of integrated circuits, the demand for vacuum chuck that provide higher precision and performance for component clamping has been increasing. The vacuum chuck is connected to the vacuum equipment through a connecting pipe. When the vacuum chuck comes into contact with the object to be processed, such as sheet or film materials, the vacuum equipment starts to work, creating negative pressure inside the vacuum chuck. Under the action of atmospheric pressure, the object to be processed firmly adheres to the vacuum chuck, and then the corresponding processing operation can be carried out. When the workpiece to be processed is completed, the vacuum equipment stops working, and air is slowly filled into the vacuum chuck. The workpiece automatically separates from the vacuum chuck, completing the processes of clamping, processing and handling of the workpiece. Traditional vacuum chuck are through-hole metal chuck, such as aluminum alloy and stainless steel chuck. Due to the large size of the adsorption holes, when adsorbing and fixing surface mount/thin film components, the gas pressure will cause local elastic deformation of the thin sheet or thin film material near the adsorption holes, which brings adverse effects to subsequent processing operations such as circuit printing. At present, porous ceramics with pore sizes at the micrometer level are commonly used as vacuum chuck. Meanwhile, to prevent interference caused by stray light reflected from the chuck during the photolithography processing of electronic components, the color of the vacuum chuck is required to be black. At present, all the black porous ceramic vacuum chuck used by electronic component manufacturers in our country are imported from abroad and are very expensive.
Therefore, the research and preparation of new black porous ceramic vacuum chuck by Fountyl Technologies is of great significance and has broad application prospects for eliminating import dependence and reducing the production costs of domestic enterprises. Black alumina ceramics are made by sintering Al2O3 as the main component, transition metal oxides as colorants, and sintering AIDS added at a certain temperature. Among them, the colorant is an important component of this type of ceramic and determines the final color. When choosing colorants for such ceramics used as vacuum chuck, it is necessary to ensure the degree of coloration, mechanical strength, porosity and pore size of the vacuum chuck.
At present, the commonly used transition metal oxides as colorants at home and abroad include Fe2O3, CoO, NiO, Cr2O3, MnO2, etc., among which Fe2O3, CoO, NiO, and MnO2 are the most frequently used. This is because alumina has a relatively weak volatilization at high temperatures, while the opposite is true for transition metal oxides; the higher the temperature, the faster the volatilization. These oxides form spinel-type compounds during high-temperature sintering, and their volatility will be reduced. Therefore, to suppress the volatilization of transition metal oxides, appropriate process conditions should be selected to enable them to combine into spinel-type compounds at lower temperatures.
Preparation of black alumina ceramics
At present, in the industry, two-step sintering and one-step sintering methods are often used to prepare such ceramics. A synthetic method is the alumina oxide, shaded, cosolvent directly according to certain proportion and process for the preparation of alumina black. This method is simple in process, but the coloring of ceramics is slightly worse than that of the secondary synthesis method. The reason is that coloring oxides such as Fe2O3, Cr2O3, CoO, V2O5, NiO and Mn2O3 all have strong volatility at high temperatures. The secondary synthesis method involves first synthesizing black pigments using some metal oxides, and then preparing black alumina by combining the black pigments, co-solvents, and alumina in a certain proportion and process. This method is rather complicated in process and has high energy consumption.
Black porous alumina ceramics were prepared by gel injection molding
Porous alumina ceramics are a type of ceramic material with alumina as the matrix, which is sintered at high temperatures and contains a large number of micro-pores or porous structures that are interconnected and also communicate with the surface. The pore structure and specific chemical composition inside porous ceramics directly affect their morphology and properties, and the most important factor influencing the pore structure is the preparation process and method.
The gel injection molding method involves adding high-molecular organic substances to the ceramic slurry. The polymerization reaction it generates causes the ceramic slurry to solidify in situ to form a green body. The water in the green body evaporates, leaving pores. Finally, sintering is carried out at high temperatures to decompose the high-molecular organic substances in the green body. Thus, a porous ceramic material with a certain porosity is obtained. The porosity of the black porous alumina ceramic used for vacuum chuck needs to reach about 40%.
During the preparation of black porous alumina ceramics, an appropriate amount of sintering AIDS are added. Due to the fact that the lattice constant of the alumina matrix is not much different from that of some sintering AIDS, solid solutions or new phases are easily formed during the sintering process, causing lattice distortion and thereby reducing the sintering temperature. Oxide (MnO2) generates a liquid phase during the sintering process. Due to the fluidity of the liquid phase and the effect of surface forces, the diffusion rate of atoms is accelerated, promoting the formation of mixed spinel compounds and causing ceramic samples to present varying degrees of color. According to relevant experimental research, when the content of sintering AIDS is the same, reducing the content of alumina and increasing the content of colorants will deepen the color.
The influence of sintering AIDS and colorants on black porous alumina ceramics
Preparation with the method of ceramic pore rate can reach 95%, general for nanoscale aperture, and the porosity distribution is relatively uniform, in the process of preparation of porous alumina ceramic black add right amount of sintering additives, due to the lattice constant of alumina substrates were similar, with some sintering additives on sintering process is easy to form solid solution or a new phase, make the lattice distortion, Thereby reducing the sintering temperature; Oxide (MnO2) generates a liquid phase during the sintering process. Due to the fluidity of the liquid phase and the effect of surface forces, the diffusion rate of atoms is accelerated, promoting the formation of mixed spinel compounds and causing ceramic samples to present varying degrees of color. According to relevant experimental research, when the content of sintering AIDS is the same, reducing the content of alumina and increasing the content of colorants will deepen the color.
As the sintering temperature of the samples prepared by the gel injection molding method is 1250℃, which is relatively low, and since both the oxides Fe2O3 and MnO2 have both coloring and fluzing effects, the porosity will decrease as the content of the colorant gradually increases. Subsequently, as the content of the colorant further increases, a certain amount of MnO2 will vaporize at a higher temperature. It plays a role similar to foaming, thereby increasing the porosity.
Vacuum chuck made of porous ceramics use ultra-fine micron-sized holes and hole spacing, which can reliably handle thinner and more delicate workpieces. Meanwhile, this vacuum chuck can adsorb workpieces of different sizes without the need to maintain a series of shapes and sizes for different workpieces, thereby saving costs and improving work efficiency. At present, domestic black porous ceramic vacuum chuck still rely on imports. Studying their process principles and preparation directions is of great significance for enterprises to reduce costs.
Fountyl Technologies Pte Ltd., introduced Japanese technology to research and produce various types of porous ceramic vacuum chucks, especially black matte porous ceramics. Currently, they have been in mass production. Relying on 13 years of technical experience, Fountyl has become the preferred supplier of ceramic chuck in the semiconductor industry.
