Ultrasound-assisted electrodeposition of Fe-Ni film for OLED mask

Abstract Fe-Ni alloy is considered as the most suitable metal for OLED mask making due to its excellent properties. However, electrodeposited Fe-Ni film is often companied with poor surface quality and thermal expansion. To get proper film for masks making, experiments of electroforming Fe–Ni were performed with different ultrasonic powers and current densities. Results show that Fe-Ni film with smooth surface could be electrodeposited at high current density due to the reducing of internal stress of film by ultrasonic power. The iron content, grain size, micro-hardness and Young’s modulus of film all present an upward trend with ultrasonic power increases from 13 W to 93 W, and then a downward trend due to the intensively transient cavitation caused by higher ultrasonic power 120 W. With the ultrasonic power of 93 W and current density of 1 A/dm2, a good surface quality of Fe-Ni films with 60.07 wt.% iron content, microhardness 351 HV, Young's modulus 167.5 GPa and CTE 3.38 × 10−6/℃ can be electrodeposited.