Abstract: Due to the lack of uniform specifications, how to use alcohol to efficiently and quickly determine the leak point has always been a key concern for vacuum coating companies. In this paper, the effectiveness of the alcohol spray leak detection in vacuum coating equipment is studied, and the cesium mass spectrometer leak detection is used for verification and calibration. The three main influencing factors including air pressure working range, pumping rate and leak point structure are systematically studied. The following conclusions, the alcohol-based leak detection and helium mass spectrometry leak detection of vacuum coating equipment were studied. It was mainly found that, in the 1.0×10^-1Pa~9.9×10^-1Pa pressure range due to the large size of the leak point, after the alcohol is sprayed, the air pressure rises directly and then falls. However, in the air pressure range of 5.0×10^-3Pa~9.9×10^-2Pa, the air pressure trend of alcohol leakage detection is firstly decreased, then increased and then decreased. When the air pressure is lower than 5.0×10^-3Pa, the alcohol leak detection cannot detect the leak point. At different pump speeds, compared with the operation of two molecular pumps, the alcohol and helium mass spectrometer leak detectors have a long waiting time and are prone to miss detection when a molecular pump is working for leak detection. In the case of alcohol leak detection, the complex leaky point pressure reaction takes longer than the simple structure leak point. The above research results provide effective guidance for vacuum production and application units using alcohol efficient and easy leak detection.

Key words: vacuum, leak detection, alcohol, helium mass spectrometer leak detector