Hermetically sealed electronic components such as MEMS, crystal oscillators and semiconductor devices are used in a wide range of applications.
High speed inspection
The test method by immersion (Fluorocarbon + helium) and test method of FUKUDA products (air + helium) are described in the diagram below.
Carry out gross leak testing using differential pressure type air leak testing. The leak rate of the test piece is detected as values by placing test piece and master into small capsules and comparing the pressure. For example, in the case of 1612 size, it is possible to measure up to equiv. 2×10-7 Pa・m3/s equivalent standard leak rate.
In order to test for minute defect apertures which cannot be detected using gross leak measurement, high-sensitivity type measurement called fine leak measurement is carried out using helium gas rather than air. Before measurement begins, the test piece is placed in a chamber (a pressure vessel to be charged with a helium atmosphere) and filled (bombed) with helium to at least 100 kPaG. If minute defect aperture(s) are present in the test piece, helium gas will enter the test piece through these apertures, and the helium partial pressure inside the test piece will gradually rise. After being bombed with helium for a set length of time, the test piece is removed from the chamber. Any helium gas which entered the test piece through the defect apertures will be discharged into the atmosphere immediately after removal from the chamber. Fine leak measurement detects the volume of this helium gas discharged into the atmosphere to measure the leak rate of the test piece. The amount of helium gas which enters the test piece depends on the internal volume of the test piece, the helium bombing pressure, and the helium bombing time. Furthermore, as the volume of helium gas discharged decreases over time, the detectable helium gas volume also decreases. Thus, time management after the test piece is removed is critical to the process. At FUKUDA, we call the time elapsed over this period “dwell time.”