Effect of Post-detachment Cleaning on the Hydrophilic Nature of Nickel Thin Film Nozzle Plates for Piezo Ink-jet Printer Heads

摘要

A hydrophilic nickel nozzle plate used in piezo inkjet printer heads with a minimum 5 deg water contact angle was obtained by (1) primary cleaning of the detached nickel nozzle plate by immersion for 90 sec in a thoroughly pre-electrolyzed 20 wt percent NaOH solution maintained at 97 deg C (207 deg F) and (2) secondary cleaning by 1 min of scrubbing with a wiper soaked with a newly formulated post-treatment cleaner to remove surface oxides and corrosion product films. Successfully obtaining a hydrophilic nickel nozzle plate surface was attributable to (1) thorough pre-electrolysis of the primary 20 wt percent NaOH cleaner solution to remove dissolved oxygen and platable cations and (2) proper formulation of the post-treatment cleaner solution, especially in the selection of a non-ionic block copolymer type of surfactant. Pre-electrolysis must be carefully carried out to avoid possible aqueous caustic corrosion of the nickel nozzle plate as the stable region of the passivating NiO or Ni(OH)_2 films at 97 deg C (207 deg F) is smaller than that at room temperature. The effect of post-treatment cleaning was experimentally substantiated by measurement of the water contact angle on the post-treatment cleaned nickel nozzle plate surface.