A test system to improve the reliability of a printhead was developed and various printheads was tested. We developed a thermally driven monolithic inkjet printhead comprising dome-shaped ink chambers, thin film nozzle guides and omega-shaped heaters integrated on the top surface of each chamber. In a durability test of an inkjet printhead, the test system automatically detects a heater failure using a Wheatstone bridge circuit. Various models were designed and tested to develop a more reliable printhead. Three design parameters of the thickness of heat-transmission layer, reinforcement layer, and insulation layer were investigated in the test. Specially, the reinforcement layer was introduced to improve the lifetime of printhead. The thicker the heat-transmission layer as well as the insulation layer, the longer the life of the printhead. The lifetime of a heater with a reinforcement layer was longer than the lifetime of a heater without a reinforcement layer.

This paper presents the results of tensile tests for lead zirconate titanate (PZT)/Platinum (Pt) thin films of 2.15 lm thickness in atmospheric air at room temperature. An axial loading tester developed by the authors was used for the tests. The tester was equipped with a load cell with a maximum capacity of 0.5 N and a non-contact position measuring system based on the principle of capacitance micrometry. Furthermore, the tester was equipped with a CCD (chargecoupled device) system for measuring the displacement of the gage length. Specimens with three different widths (50, 100 and 150 lm) were fabricated to study the size (width of specimen) effects. The elastic moduli of the specimens with 50, 100 and 150 lm width were 72.8 € 3.7, 75.0 € 1.3, 73.3 € 1.8 GPa, respectively. In addition, the ultimate tensile strength of the specimens with 50, 100 and 150 lm width were 263.4 € 21.1, 238.6 € 4.5, 221.1 € 13.9 MPa, respectively. It was observed that the width of specimen has little effect on the elastic modulus of PZT/Pt thin films but has an effect on the ultimate tensile strength of PZT/Pt thin films and the ultimate tensile strength decreases as the width increases. It was assumed that the scatter in the ultimate tensile strength of 50 lm width was attributed to delamination of PZT/Pt layers before the fracture in the tensile test. The 0.2% offset yield strength could not be measured because the PZT/Pt thin film is very brittle.Keywords: Lead zirconate titanate thin film (PZT) / platinum (Pt) / micro tensile test / tensile strength / elastic modulus / thin film / Schlüsselwörter: dünne Blei-Zirkonat-Titanat (PZT) Schicht / Platin (Pt) / Mikrozugversuch / Zugfestigkeit / elastischer Modul / dünne Schicht /

Micro-tensile properties of Au thin films were measured using a membrane deflection testing system. During the membrane deflection test, the deflection of the film was measured by an out-of-plane electronic speckle pattern interferometric (ESPI) system. From the measurement, the tensile loads and strains exerted on the membrane film during the deflection of the film could be determined. Quantitative analysis of the phase maps of the ESPI speckle patterns corresponding to the respective different deflection levels provided the deflection distribution along the testing section of the film. Test pieces were fabricated by electromachining process using 0.5 and 1. 0 μm thick Au films which were deposited on the silicon wafer by sputtering technique. Tensile properties, including elastic modulus, yield and tensile strength, were evaluated in the tensile stress-strain curve determined from the load-deflection relation. These properties were compared to those obtained from the micro-tensile tests. It was found that the yield and tensile strengths obtained from the deflection tests were lesser than those from the micro-tensile tests. Furthermore, the thickness effect, showing the increasing tendency of yield strength with decreasing thickness, was experimentally examined.

In this study, fatigue tests were performed for NiCo alloy which is commonly used in probe tips of test machines of semiconductors. The smooth specimens were fabricated by MEMS process including electro-plating process on a single-side polished 6 inches (100) silicon wafer. The NiCo thin film consists of about 66.2 % Ni and 33.8 % Co. The specimen is 2000 lm long, 9 lm thick and 100 lm wide. The tests were performed using a novel test procedure, a structure of the specimen is easy to manipulate, align and grip a thin-film and a test machine proposed by the authors. The closed-loop feedback control of the magnetic-electric actuator allowed load-controlled and high cycle fatigue tests with 5 Hz frequency, in ambient environment and with a stress ratio of R = 0.1. The fatigue strength coefficient and exponent were 1324 MPa and -0.0558, respectively. In a fatigue test of thin film, it is difficult to perform the fatigue test at R = -1. However, the result of the fatigue test at R = -1 should be required when fatigue life prediction is performed under variable loading. Therefore, in this study, the modified Goodman method, Gerber method and Soderberg method were considered to investigate which method is most reasonable when mean stress is considered.

To fabricate aluminum alloys with good drawability, the texture evolution of AA5182 sheets after rolling with high reduction ratios and subsequent annealing was studied. The measurement of the deformed textures was carried out for sheets with high reduction ratio and the change of the recrystallization texture was investigated after heat-treatments of the rolled sheets. Rolling without lubrication and subsequent annealing led to the formation of favorable rot-C ND {001}a110A and c-fiber ND//a111A textures in AA5182 sheets. From the results, the cfiber ND//a111A component well evolved during rolling at high l/d parameter of 6.77. The initial shear deformation texture, especially, the c-fiber ND//a111A texture was not rotated during heat treatment at holding time of 180~7,200 sonds on AA5182 in present rolling condition. Since the measured textures of the AA5182 sheets were nearly the same as IF (interstitial free) steel, the plastic strain ratio (R-value) were measured. The measurement of the plastic strain ratio was carried out for the AA5182 sheets which were cold rolled by using the symmetric roll and annealed in order to analyze the sheet drawability. The average plastic strain ratio of the AA5182 sheets was 1.50. It was considered that the higher plastic strain ratio resulted from the c-fiber ND//a111A component evolved during rolling and maintained during annealing. Therefore, the AA5182 sheets were fabricated by rolling having well evolved c-fiber ND//a111A texture which is advantageous for a good drawability of the sheets.