Papers by Author: Man Sik Myung

Abstract: This paper describes new structure of specimen easy to manipulate, align and grip a thin-film and test machine for a fatigue test. High cycle fatigue test has been performed on tensile type specimen of Al-3%Ti alloy using the newly developed fatigue test machine. The material used in this study was Al-3%Ti thin film, which was used in RF MEMS switch. The structure of the suggested specimen has two holes and several bridges. The holes at centre of grip end are able to make alignment and gripping easy. The bridges are to remove the side support strip easily and extract specimen from wafer without sawing. The test machine was developed using the voice coil of speaker. The new tensile loading system has a load cell with maximum capacity of 0.5N and a non-contact position measuring system based on the principle of capacitance micrometry with 0.1nm resolution for displacement measurement. Fatigue tests was performed on 7 specimens. The thickness and width of the thin film of specimen are 1.0μm and 150μm, respectively. The fatigue strength coefficient and the fatigue strength exponent of Al-3%Ti alloy micro-sized specimen are determined to be 164MPa and -0.01322, respectively

Abstract: A new tensile tester using an electromagnetic-force actuator (voice coil) was developed to measure the mechanical characteristics of surface-micromachined thin film materials. The tester has a load cell with maximum capacity of 0.5N and a non-contact position measuring system based on the principle of capacitance micrometry with 0.1nm resolution for displacement measurement. The tester was applied for tensile testing of Al-3%Ti thin films with dimensions of 1000μm long, 50-480μm wide and 1.0 and 1.1 μm thick. The Al-3%Ti is commonly used in RF(radio frequency) microelectromechanical systems(MEMS) switch. The specimen with holes and bridges was designed for easy tensile test. The holes at center of grip end are able to make alignment and gripping easy. The bridges are to remove the side supports easily and extract specimen from wafer without sawing. It was found that the mean tensile strengths of Al-3%Ti are 140-380MPa, depending on the width of specimens and converging to a certain tensile strength as the width decreases.

Abstract: This paper describes a novel test procedure, new structure of specimen easy to manipulate, align and grip a thin-film and test machine for a tensile and fatigue test. For the proposed specimen, the surroundings of the specimen including the side support strips except for six bridges are etched during the fabrication of the specimen, which in turn makes it possible to cut off easily the specimen from the wafer by minimizing a damage to the test film and also possible to produce the specimen in mass production. For the present specimen, a small hole is made at the grip end and using a small pin for setting the specimen onto the tester, the setting process and alignment of specimen is much easier, compared to the specimen proposed by Sharpe et al. To gain confidence in reliability of testing results, pre-test using the Al-3%Ti is performed, which is widely used in the RF switch and other MEMS devices. Tensile tests are performed, from which tensile strengths of the Al-3%Ti are measured as 343±16.22MPa at 200μm width and 1.1μm thickness.