Abstract: Microelectronic technology is the cornerstone of the electronic information industry. As products become increasingly miniaturized and integrated, the bonding areas of chips have reduced to the micrometer scale, demanding dispensing position accuracy and glue droplet consistency at the microliter and even nanoliter levels. The wear and distortion of the impact needle, a critical component of the dispensing valve, are the primary failure modes leading to a reduction in the service life of the valve. To address these issues, a cyclic dispensing experiment involving hundreds of millions of cycles is conducted, alongside microstructural characterization analysis. The experiment aimed to elucidate the fretting wear mechanisms of the needle under impact conditions. A fretting wear model for the needle is developed, and dynamic simulations are used to analyze the trends in impact force and displacement during the wear process. Principles of fluid dynamics are integrated to clarify the influence of needle wear on dispensing consistency. Based on the requirements for dispensing accuracy, a failure threshold is defined, enabling precise prediction of the dispensing valve needle lifespan through the wear model. This approach reduces detection and maintenance costs for dispensing valves and provides a theoretical foundation and technical support for the lifespan prediction of domestically produced, high-reliability, long-life dispensing robots.

Key words: dispensing valve needle, impact fretting wear, fluid dynamics, life prediction