Article history:Invar is a compound metal of Fe-Ni system contained 36.5% Ni. The characteristic of invar is that the coefficient of thermal expansion is 1.0×10 -6 cm/°C. It is approximately 10 times smaller than series of steel. Because of this low thermal expansion characteristic of Invar, it is used to shadow mask of display device such as UHDTV or OLED TV. In this study, pulse current from pulse generator instead of DC current is used to overcome the disadvantages of the conventional electrochemical machining. Pulsed current with different duty factor in PECM affect the precise geometry. Pulse electrochemical machining is conducted to machine the micro hole to the invar sheet with different duty factor. The machined shape and overcut of invar sheet with different duty factor is observed by optical microscope and scanning electron microscope (SEM). . 또한, 펄스전해가공은 기존