NOZZLE PLATE AND ITS MANUFACTURE

PROBLEM TO BE SOLVED: To reduce sagging occurring at the time of processing by an excimer laser, facilitate adhesion, and form nozzle holes of a beautiful shape by setting the numerical aperture of a processing lens used for the processing of a nozzle plate with an excimer laser at a specified value. SOLUTION: By setting the numerical aperture of a processing lens used when nozzle holes are processed with an excimer laser at 0.13 or higher, the processing resolution can be improved, and sagging can be prevented. In other words, the numerical aperture should be preferably at least 0.13 in respect of the amount of sagging. An increase in the numerical aperture decreases the depth of a focus A decrease in the depth of a focus means more difficulty in alignment at the time of processing. When the aperture is 0.35, the depth of a focus becomes 1μm. A further decrease in the depth of a focus makes alignment very difficult. In other words, the numerical aperture is preferably 0.35 or less in respect of the depth of a focus.