High-Purity Alumina Ceramics: The Key "Ceramic" Materials in Four Major Fields
High-purity alumina ceramics are important ceramic materials that use high-purity ultra-fine alumina as the main raw material and α-Al₂O₃ as the main crystalline phase. Due to their excellent properties such as high mechanical strength, high hardness, high temperature resistance and corrosion resistance, high-purity alumina ceramics have been widely used in fields like machinery, electronics, integrated circuits and medicine.
①Precision Components for Semiconductor Equipment
It is understood that a large number of precision ceramic components are used in semiconductor equipment, and these ceramic components can account for more than 10% of the cost of semiconductor equipment. Among them, alumina ceramics are a relatively commonly used ceramic material for precision components.
Currently, high-purity Al₂O₃ coatings or Al₂O₃ ceramics are mainly used as protective materials for etching chambers and their internal components. Beyond the chambers, high-purity alumina ceramics are also required for components of plasma equipment such as gas nozzles, gas distribution plates, and retaining rings that secure wafers. For another example, in the wafer polishing process, alumina ceramics can be widely applied to polishing plates, polishing pad conditioning platforms, vacuum chucks, and other components.
②In the mechanical field
High-purity alumina ceramics possess excellent mechanical properties. Alumina ceramics with a flexural strength of approximately 250 MPa can be prepared via the atmospheric pressure sintering method, while high-purity alumina ceramics produced by the hot-pressing sintering method can achieve a flexural strength of up to 500 MPa and a hardness of up to 9 GPa (Mohs hardness). Leveraging these characteristics of high-purity alumina ceramics, they can be used as grinding wheels, ceramic pins, and other components. Among these applications, high-purity alumina ceramic cutting tools and high-purity alumina ceramic balls are the most widely used. However, due to the relatively poor fracture toughness and thermal shock resistance of high-purity alumina ceramics, it is usually necessary to introduce a second phase (such as ZrO₂) into alumina to improve the toughness and thermal shock resistance of the high-purity alumina ceramic material. In addition, by refining the grain size to produce high-purity alumina ceramics with small and uniformly distributed grains, the strength and toughness of the material can also be significantly enhanced to a certain extent.
③In the electronic and electrical fields
High-purity alumina ceramics exhibit low high-frequency dielectric loss and excellent insulating properties, making them suitable for manufacturing insulating devices, ceramic substrates, and transparent alumina ceramics. Among these applications, ceramic substrates are relatively widely used and have found increasingly extensive application in many fields such as special optical instruments, lighting equipment, and space satellite equipment.
In terms of ceramic substrates, alumina ceramic substrates are the most widely used substrate materials in the modern electronic information industry and serve as the fundamental material for integrated circuit chips. For instance, in the field of LED lighting, the coefficient of thermal expansion (CTE) of mainstream substrates ranges from 14 to 17×10⁻⁶/K. When there is an excessive temperature difference or a sudden temperature change, PCBs (Printed Circuit Boards) expand more drastically than chip packages, leading to solder joint failure. Against this challenge, the CTE of alumina ceramic substrates is much closer to that of chips, which can effectively prevent such issues.
④In the medical field
Biomedical materials can repair human body functions without causing adverse effects on the human body, and healthcare organizations have extremely strict requirements for biomedical materials. These materials are not only required to have biocompatibility but also need to possess properties such as non-toxicity, environmental friendliness, and durability. Due to its excellent biocompatibility, mechanical properties, and chemical stability, high-purity alumina ceramics do not trigger rejection reactions when implanted into the human body. Therefore, they can be widely used in the manufacture of artificial bones, bolts, artificial joints, and other medical devices, and have been recognized in clinical practice and scientific research.