Pulsed electrochemical machining (PECM) has been conducted for invar (Fe-Ni) fine sheet consisting of 64 % Fe ions and 36 % Ni ions. Solutions of sodium chloride (NaCl), acetic acid (CH 3 COOH), sodium nitrate (NaNO 3 ), and sodium nitrite (NaNO 2 ) mixed with sodium tartrate (C 4 H 4 Na 2 O 6 ) were used as an electrolyte. First, the electrical conductivities of all electrolytes have been measured. As the concentration of each electrolyte increased, the electrical conductivities of electrolytes increased except for the acetic acid. The electrochemical machinability has been investigated using four types of electrolytes. The results of PECM show that the electrolyte which has the high electrical conductivity value leads to the low electrochemical machinability. The pulse waves which indicate the electrical characteristics during the PECM has been observed and it is confirmed that the passivating oxide film occur in PECM. To compare the capability of changing in transpassive state, the anode surface has been investigated. This study presents the relationship between electrical conductivity and electrical machinability. Moreover, the capacity of changing in transpassive state has been investigated as compared with four types of electrolytes. This study shows the possibility of applying invar fine sheet in PECM and contributes to determining the electrolyte for the process.

No abstract

No abstract

Recently, invar (Fe-Ni) material has been applied to OLED shadow masks due to its thermal change characteristics and thermal expansion coefficient. The most widely used manufacturing methods for invar are etching and laser machining, but they have problems like non-machined areas generated by etching and surface burning in laser machining. For this reason, an alternative machining method is necessary. In this study, pulsed electrochemical machining (PECM) has been applied to fabricate an OLED shadow mask. PECM is a highly promising technology for shadow mask manufacturing because it can produce micro-scale and complex tapered holes in one process. A pilot experiment was carried out to find a suitable electrolyte for invar film, and an array of coated Ti electrodes was used to fabricate micro holes.