Non-wetting Coating on Fluid Ejector for Inkjet Printheads
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Solution Overview
Problem
Fluid ejectors, such as ink-jet printheads, face issues with fluid accumulation on exterior surfaces due to surface tension, leading to diversion or blockage of ejected fluid, and existing non-wetting coatings like Teflon and fluorocarbon polymers are soft, expensive, and difficult to pattern.
Innovation Solution
A fluid ejector design featuring a non-wetting layer with carbon and fluorine molecules on exterior surfaces and a hydrophilic overcoat layer made of inorganic oxide on interior surfaces, where the non-wetting layer is formed as a monolayer using vapor deposition and the overcoat layer is applied selectively to ensure improved fluid ejection properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-wetting coatings such as Teflon and fluorocarbon polymers are used to prevent fluid accumulation, then fluid repellency is improved, but coating durability and solvent resistance deteriorate
Solution Approach 1:
The patent uses a composite coating structure consisting of an inorganic oxide layer (such as silicon dioxide) combined with an organic non-wetting layer. This composite approach allows the inorganic base layer to provide durability and solvent resistance, while the organic non-wetting layer provides fluid repellency. The combination resolves the contradiction by integrating materials with complementary properties.
Solution Approach 2:
The patent changes the chemical composition parameters of the coating by using inorganic oxides with specific surface properties that can be modified to achieve both durability and non-wetting characteristics. By adjusting the oxide type, surface treatment, and organic layer composition, the coating achieves improved durability while maintaining fluid repellency.
2Reliability
If non-wetting coatings are applied to exterior surfaces, then fluid accumulation is reduced, but manufacturing complexity and patterning difficulty increase
Solution Approach 1:
The patent applies non-wetting properties selectively to specific exterior surfaces where fluid accumulation is most problematic, rather than coating entire components. This localized application reduces manufacturing complexity by focusing the coating process only on critical areas, thereby maintaining fluid accumulation prevention while improving ease of manufacture.
3Reliability
If soft non-wetting coatings are used, then fluid repellency is achieved, but coating durability and resistance to mechanical degradation worsen
Solution Approach 1:
The patent employs a composite structure where a hard inorganic oxide base layer provides mechanical durability and long service life, while an organic non-wetting layer applied on top provides fluid repellency. This composite material approach resolves the contradiction between soft non-wetting properties and coating durability by combining materials with complementary strengths.
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 solution reduces fluid accumulation on exterior surfaces, enhances the durability and solvent resistance of the non-wetting layer, and allows for improved control over droplet size and ejection rate by ensuring the interior surfaces are highly wetting, thus improving the reliability and versatility of the fluid ejector.
Implementation Method 1
non-wetting layer covering portions of at least the first surface... The non-wetting layer may include molecules which include at least one atom each of carbon and fluorine... The non-wetting layer may be hydrophobic
Implementation Method 2
an overcoat layer covering portions of the second surface but not a substantial portion of the first surface, the overcoat layer being more wetting than the non-wetting layer... The overcoat layer may include an inorganic oxide, such as silicon dioxide... The overcoat layer may be hydrophilic
Implementation Method 3
The non-wetting layer may be formed directly on an inorganic seed layer... The non-wetting layer can be durable and can be insoluble in most solvents... deposited by vapor deposition
Data Source
Figure 1A~1C
Figure 1D~1F
Figure 1G
AI summary
A fluid ejector having a first surface, a second surface, and an orifice that allows fluid in contact with the second surface to be ejected. The fluid ejector has a non-wetting layer exposed on at least a first surface of the fluid ejector, and a overcoat layer exposed on a second surface, the overcoat layer being more wetting than the non-wetting layer. Fabrication of this apparatus can include depositing a non-wetting layer on the first and second surfaces, masking the first surface, optionally removing the non-wetting layer from the second surface, and depositing an overcoat layer on the second surface.