Helium leak detectors: from a laboratory device to dedicated industrial leak test units

• Published in: Vacuum 1993-05, Vol.44 (5), p.627-632
• Main Author: Bley, Werner Große
• Format: Article
• Language: English
• Subjects: Exact sciences and technology; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Mass spectrometers and related techniques; Physics
• ISSN: 0042-207X; 1879-2715
• DOI: 10.1016/0042-207X(93)90112-N

The development of helium leak detectors was stimulated by the requirement for the detection of very fine leakages in vacuum devices. The idea of using a small mass spectrometer together with the choice of helium as a tracer gas turned out to be very successful. The helium leak detector—first a great hulking machine—developed into a variety of specialized units and, in the last few years, portable versions became possible. The basic specifications of leak detectors will be described in their relevance and how the so called counterflow technique revolutionized the performance by making liquid nitrogen dispensable will be discussed. The real industrial unit was finally possible because all the complicated jobs of tuning, zeroing, ranging and calibrating are nowadays done by the built-in microprocessor. As examples, a testing machine for semiconductor devices and a detection module for industrial testing are described. Looking at the future, two perspectives show up: for vacuum leak detection more specialized units with less or smaller pumps operating oilfree and in higher pressure regions are the developmental trend. For overpressure leak detection new principles without pumps and mass spectrometers (membrane techniques?) could be a possible direction of development.