The basic concepts of vacuum coating equipment leak detection, an ideal vacuum system or vacuum container, should be existed without any leak, no producing any leak phenomenon. However, any vacuum system or vacuum vessel, it is impossible that there is no leak phenomenon. Especially in the case of low pressure, as the impact of growing air leaks, the vacuum can not reach a predetermined process requirements, is a fairly common problem. To this end, the detection vacuum system or the existence of the vacuum vessel leak site determines the size of the leak, and plugging the drain hole to eliminate leak current. It has become an important task for vacuum technicians.

1. Virtual Leak

With respect to a physical phenomenon is real in terms of leak. This phenomenon is mostly due to material out-gassing, absorption, gas condensate solution or system memory evaporated gas, flowing in the dead space and other reasons, then causing a phenomenon by its vacuum system or elevated pressure vessel. When the vacuum leak detection works, you need to eliminate the influence of the virtual leak.

2. Air Tightness.

It is the characterization of the vacuum system or container wall in a performance level of the air-impermeable.

3. Leak Poles. 

It refers to the presence of the wall of the vacuum with undefined shape, small holes or gaps, The atmosphere goes into the vacuum system or container by those small holes or gaps.

4. The Leak Rate

That leak rate, which defines that the atmosphere goes through the leak gap, or the amount of gas flowing to the vacuum system or vessel in the unit of time. 

5. The Minimum Leak Rate.

It refers to the use of a leak detection method or instrument detected with the smallest possible leak rate.

6. Leak Detection Sensitivity

So called as defective sensitivity, leak can be detected for the smallest leak rate in the good working condition.

7. The Reaction Time.

Also known as the response time, it is the time which rises to a peak of 63% from the implementation of leak detection method (such as start leaking gas injection) to leading method or instrument indicated value.

8. The Elimination Time.

It refers to that the leak detection drops to 37% of the time from stopping (such as sputtering gas leake)to indicated method or instrument value.

9. Clogging the Leak Holes.

It refers to the leakage of dust or liquid caused by the blockage, the blockage often leads to leak due to improper operation, then forming a temporary phenomenon. when  detected without leak, but it will appear a phenomenon of gas through the exhaust.