Micromachining of alumina ceramic for microsystems applications: a systematic review, challenges and future opportunities

This review article presents the current status of various micromachining techniques used to create microfeatures in alumina ceramic. Alumina has emerged as an advanced substrate in various radio-frequency communication and automotive packaging applications due to its superior electrical resistivity, lower dielectric loss, higher wear resistance, and dimensional stability at high temperatures. However, creating complex-shaped microfeatures in alumina is challenging due to its hard and brittle nature. Traditional contact-based methods fail to create microsized shapes in alumina; thus, the researchers are exploring novel machining methods, like abrasive, thermal, chemical, and hybrid micromachining processes. This review article comprehensively summarizes various micromachining methods used to create microfeatures in alumina ceramics. The mechanism, unique features, pros/cons, novelty, and applications of ultrasonic machining, laser ablation, electrochemical discharge machining, abrasive-jet machining, etc., are presented. The associated processing challenges in various alumina micromachining and the potential remedies to produce high-quality alumina microparts for microelectronics applications are discussed.