Cascade Impactor Nozzle Plate Micro-Orifice Manufacturing
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Solution Overview
Problem
Current nozzle plates in cascade impactors suffer from particle clogging due to uneven inner surfaces and fragile structures, leading to measurement errors and difficulties in cleaning, especially in the last stages where micro-orifices are prone to blockage and damage from improper cleaning methods.
Innovation Solution
A method for manufacturing nozzle plates with multiple micro-orifices featuring a smooth inner surface and uniform wall thickness, achieved through semiconductor processes like lithography, etching, and electroplating, using a mix of nickel and cobalt for the metal material, which allows for easy cleaning with ultrasonic cleaners and reduces clogging by gradually expanding the orifice diameter from the bottom to the top.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser drilling is used to manufacture micro-orifices, then the orifice diameter can be precisely defined, but the wall thickness becomes too thin (about 10 μm) causing fragile structure and abrupt steps that lead to clogging
Solution Approach 1:
The patent changes the manufacturing method from laser drilling to a multi-step process involving wet etching followed by electroplating. This parameter change in the manufacturing process allows for controlled wall thickness and smooth transitions, eliminating the abrupt steps and fragility caused by laser drilling while maintaining precise orifice diameter control through photoresist masking and controlled etching depths.
Solution Approach 2:
The patent creates a composite structure by combining the substrate material with a metal coating layer applied through electroplating. This composite approach allows the nozzle plate to have both the precise geometry defined by the photoresist mask and the enhanced mechanical strength and smooth surface provided by the metal coating, eliminating the fragility of thin-walled laser-drilled structures.
2Ease of operation
If high intensity ultrasonic cleaning is used to eliminate dust accumulation, then cleaning effectiveness is improved, but the fragile nozzle plates with thin walls are damaged
Solution Approach 1:
The patent applies a metal coating layer to the nozzle plate structure before use and cleaning operations. This coating acts as a protective cushion that strengthens the structure against the harsh mechanical stresses of ultrasonic cleaning, allowing effective dust removal without damaging the underlying substrate. The coating absorbs the mechanical stress that would otherwise damage thin-walled laser-drilled nozzles.
3Manufacturing precision
If the bottom part of orifice is made by laser drilling, then the orifice diameter is precisely defined, but an abrupt step is created at the bottom rendering clogging easily
Solution Approach 1:
The patent changes the geometry parameter of the orifice bottom from an abrupt step (laser drilling result) to a gradual transition profile. This is achieved by controlling the wet etching depth to create a tapered bottom followed by electroplating that fills and smooths the transition. The gradual profile eliminates the abrupt step that causes particle accumulation and clogging, while the photoresist mask maintains precise orifice diameter definition.
Solution Approach 2:
The patent replaces the mechanical laser drilling process with a chemical wet etching process followed by electroplating. The chemical etching allows for more controlled material removal that creates smooth transitions, and the electroplating further smooths the surface. This substitution of manufacturing mechanisms eliminates the abrupt steps inherent in laser drilling while maintaining dimensional precision through photoresist masking.
4Ease of manufacture
If wet etching process is used for the major part of nozzle, then manufacturing is simplified, but the final bottom part requires laser drilling creating structural weaknesses
Solution Approach 1:
The patent merges the wet etching process with an electroplating process to create a unified manufacturing approach. The wet etching creates the basic orifice structure and tapered bottom, then electroplating is applied to strengthen the walls and smooth the surface. This combination eliminates the need for a second laser drilling step, maintaining manufacturing simplicity while significantly improving structural integrity and eliminating the weaknesses caused by laser drilling.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The smooth inner surfaces prevent particle clogging, and the sturdy structure facilitates effective cleaning, enhancing the accuracy and reliability of aerosol sampling by maintaining the specified cut-off aerodynamic diameters and reducing pressure drops across the nozzles.
Implementation Method 1
electroplating a metal material onto the seed layer
Data Source
AI summary
A nozzle plate containing multiple micro-orifices for the cascade impactor and a method for manufacturing the same are disclosed. The nozzle plate is formed by a series of semiconductor processes, including lithography, etching and electroplating. The nozzle plate comprises a plate body and a plurality of micro-orifices formed on the plate body. The orifice has a diameter which gradually expands in the direction away from the bottom of the plate body to achieve a smooth inner surface, allowing particles to pass therethrough smoothly without being clogged in the nozzle plate.