Abstract:
An aperture plate is manufactured by plating metal around a mask of resist columns (2) having a desired size, pitch, and profile, which yields a wafer about 60µm thickness. This is approximately the full desired target aperture plate thickness. The plating is continued so that the metal (3) overlies the top surfaces of the columns until the desired apertures (4) are achieved. This needs only one masking/plating cycle to achieve the desired plate thickness. Also, the plate has passageways (24) formed beneath the apertures (32), formed as an integral part of the method, by mask material removal. These are suitable for entrainment of aerosolized droplets exiting the apertures (32).
Abstract:
An aperture plate (10) is formed from a palladium nickel alloy comprising about 89% palladium and about 11% nickel. There is a generally fine substantially equiaxed grain microstructure throughout the thickness of the aperture plate. The average grain width (W) is in the range of from 0.2 µm to 2.0 µm, in some cases from 0.2 µm to 1.0 µm. For optimum results the average grain width is approximately 0.5 µm. Because the grain structure is equiaxed (L/W =1) the grain length (L) is the same as the grain width. The improved aperture plate (10) extends the life of nebulisers, eliminates the risk of premature and unpredictable failure of a nebuliser in service, eliminates the risk of product returns from hospitals and patients, and eliminates the possible risk of fragments of the aperture plate breaking free from the nebulizer.