IEC 62047-38:2021 pdf download-Semiconductor devices – Micro-electromechanical devices.
5 Testing method and test apparatus 5.1 Test principle The test is performed by applying the contact load on the metal powder paste using a cleaned glass lens with a few millimetre curvature, and then by detaching the lens from the paste to evaluate the adhesion strength of the paste. A test example can be found in Annex A. During the loading process, the metal powder in the paste is deformed by the contact with the lens and the contact area between the lens and the metal powder is formed. The changes in the contact area are recorded by an optical microscope and CCD camera. The contact area is calculated by analyzing the recorded images after the test. During the unloading process, the contact load is decreased and a pulling force is applied on the interface between the lens and the paste due to the adhesion between them. After the maximum pulling force reaches, the contact area is rapidly decreased and the lens is completely separated from the paste. The adhesion strength of the metal powder paste can be evaluated by dividing the maximum pulling force with the contact area between the lens and the metal powder measured before the unloading process. The lens can be coated with thin metal films such as Au and Al for simulating the electrode materials of MEMS. 5.2 Test apparatus The test machine is shown in Figure 2. The glass lens is fixed on the top of the chamber by clamping and the metal powder paste test piece is installed on the sample stage. The test piece is moved toward the glass lens by moving the z-axis motorized stage for the loading process and then is separated from the lens by moving down the z-axis stage for the unloading process. During the test, the force is measured by loadcell, and optical images of the contact area are recorded using an optical microscope and CCD camera. The contact area images shall be recorded at a speed larger than 30 Hz using a camera with a microscope objective of 20x or more.