Invar alloy consisting of 64% iron and 36% nickel has been widely used for the production of shadow masks for organic light emitting diodes（OLEDs） because of its low thermal expansion coefficient（1.86 × 10^-6c...Invar alloy consisting of 64% iron and 36% nickel has been widely used for the production of shadow masks for organic light emitting diodes（OLEDs） because of its low thermal expansion coefficient（1.86 × 10^-6cm/°C）.To fabricate micro-hole arrays on 30 lm invar alloy film,through-mask electrochemical micromachining（TMEMM） was developed and combined with a portion of the photolithography etching process.For precise hole shapes,patterned photoresist（PR） film was applied as an insulating mask.To investigate the relationship between the current density and the material removal rate,the principle of the electrochemical machining was studied with a focus on the equation.The finite element method（FEM） was used to verify the influence of each parameter on the current density on the invar alloy film surface.The parameters considered were the thickness of the PR mask,inter-electrode gap（IEG）,and electrolyte concentration.Design of experiments（DOE） was used to figure out the contribution of each parameter.A simulation was conducted with varying parameters to figure out their relationships with the current density.Optimization was conducted to select the suitable conditions.An experiment was carried out to verify the simulation results.It was possible to fabricate micro-hole arrays on invar alloy film using TMEMM,which is a promising method that can be applied to fabrications of OLEDs shadow masks.展开更多
A high friction coefficient and a low wear rate of contacted surfaces are essential elements to friction pairs between the stator and the rotor in ultrasonic motors. It has been shown that surface textures have a sign...A high friction coefficient and a low wear rate of contacted surfaces are essential elements to friction pairs between the stator and the rotor in ultrasonic motors. It has been shown that surface textures have a significant effect on improving the tribological performance of friction pairs.In this paper, microgroove arrays are introduced to the stator surface for improving the tribological performance of friction pairs between the stator and the rotor in ultrasonic motors. Microgrooves were fabricated on a phosphor bronze surface by through-mask electrochemical micromachining（TMEMM）. Parameters, namely, the electrolyte inlet pressure, applied voltage, pulse duty cycle,and frequency, were varied to investigate their influences on the dimensions and morphology of the microgrooves. Results showed that the width and depth of the microgrooves were strongly affected by the applied voltage and frequency, while the morphology of the microgrooves was dependent on the electrolyte inlet pressure and the pulse duty cycle. Compared with a smooth surface, the friction coefficient increased from 0.245 to 0.334 and less abrasion was obtained when a surface was textured with microgrooves of which the width and depth were 185.6 and 57.6 lm,respectively. Microgroove arrays might play an important role in enhancing the performance of ultrasonic motors.展开更多
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIP)(No.2015R1A2A1A15054116)
文摘Invar alloy consisting of 64% iron and 36% nickel has been widely used for the production of shadow masks for organic light emitting diodes（OLEDs） because of its low thermal expansion coefficient（1.86 × 10^-6cm/°C）.To fabricate micro-hole arrays on 30 lm invar alloy film,through-mask electrochemical micromachining（TMEMM） was developed and combined with a portion of the photolithography etching process.For precise hole shapes,patterned photoresist（PR） film was applied as an insulating mask.To investigate the relationship between the current density and the material removal rate,the principle of the electrochemical machining was studied with a focus on the equation.The finite element method（FEM） was used to verify the influence of each parameter on the current density on the invar alloy film surface.The parameters considered were the thickness of the PR mask,inter-electrode gap（IEG）,and electrolyte concentration.Design of experiments（DOE） was used to figure out the contribution of each parameter.A simulation was conducted with varying parameters to figure out their relationships with the current density.Optimization was conducted to select the suitable conditions.An experiment was carried out to verify the simulation results.It was possible to fabricate micro-hole arrays on invar alloy film using TMEMM,which is a promising method that can be applied to fabrications of OLEDs shadow masks.
基金supported by the National Basic Research Program of China (973 Program,No.2015CB057502)the Fundamental Research Funds for the Central Universities (No.NZ2016106)
文摘A high friction coefficient and a low wear rate of contacted surfaces are essential elements to friction pairs between the stator and the rotor in ultrasonic motors. It has been shown that surface textures have a significant effect on improving the tribological performance of friction pairs.In this paper, microgroove arrays are introduced to the stator surface for improving the tribological performance of friction pairs between the stator and the rotor in ultrasonic motors. Microgrooves were fabricated on a phosphor bronze surface by through-mask electrochemical micromachining（TMEMM）. Parameters, namely, the electrolyte inlet pressure, applied voltage, pulse duty cycle,and frequency, were varied to investigate their influences on the dimensions and morphology of the microgrooves. Results showed that the width and depth of the microgrooves were strongly affected by the applied voltage and frequency, while the morphology of the microgrooves was dependent on the electrolyte inlet pressure and the pulse duty cycle. Compared with a smooth surface, the friction coefficient increased from 0.245 to 0.334 and less abrasion was obtained when a surface was textured with microgrooves of which the width and depth were 185.6 and 57.6 lm,respectively. Microgroove arrays might play an important role in enhancing the performance of ultrasonic motors.
