Thermal Oxide Coating on Fluid Ejector for Etching Resistance
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Solution Overview
Problem
Fluid ejectors, such as ink-jet printheads, face surface degradation and non-uniformity due to aggressive or alkaline fluids, leading to inaccuracies in fluid ejection.
Innovation Solution
A fluid ejection module is developed with a flow-path body and membrane coated with thermal oxide layers, ensuring uniform thickness and density, which are bonded together to form a dense, inert surface resistant to etching, avoiding high-temperature oxidation that could cause warping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal oxide coating is applied to protect fluid ejector surfaces from aggressive fluids, then resistance to etching and surface degradation is improved, but manufacturing complexity increases due to separate coating and bonding processes
Solution Approach 1:
The oxide layers are formed on the membrane and flow-path body surfaces before bonding occurs. This preliminary oxidation protects the surfaces that will be exposed to fluids during operation, while avoiding the need to oxidize the entire assembled device at high temperatures.
Solution Approach 2:
The fluid ejector is divided into separate components (membrane, flow-path body, nozzle plate) that are individually coated with oxide layers before assembly. This segmentation allows selective oxidation of only the surfaces requiring protection, simplifying the overall manufacturing process compared to oxidizing the complete assembled device.
2Reliability
If high temperature thermal oxidation is applied to the entire bonded fluid ejector, then oxide layer formation is achieved, but warping occurs in the membrane and structural components
Solution Approach 1:
The thermal oxidation process is performed on individual components before bonding, not on the assembled device. This prevents the high temperatures required for oxidation from causing warping in the membrane and structural components, while still achieving the desired oxide layer protection on critical surfaces.
Solution Approach 2:
By separating the oxidation step from the assembly step, the process applies thermal stress to individual components rather than the complete bonded structure. This segmentation prevents warping issues that would arise from heating the entire assembled device, particularly protecting the membrane from thermal deformation.
3Reliability
If uniform oxide coating is applied to protect all surfaces, then resistance to fluid attack is improved, but coating precision requirements increase to maintain thickness uniformity
Solution Approach 1:
Oxide layers are applied selectively to specific surfaces that require protection from fluid attack, rather than uniformly coating all surfaces. The inner surfaces of flow paths, membrane surfaces, and nozzle interior surfaces receive oxide coating, while exterior surfaces may remain uncoated or receive different treatment, optimizing both protection and manufacturing feasibility.
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 provides consistent and accurate fluid droplet ejection by creating a resistant, uniform oxide layer that prevents surface degradation and maintains structural integrity, reducing warping and enhancing ejection precision.
Implementation Method 1
Using a thermal oxide process to coat the fluid paths creates a dense oxide layer
Implementation Method 2
bonding the first thermal oxide layer to the second thermal oxide layer. The bonding can occur at a temperature of greater than approximately 1000° C.
Data Source
AI summary
A fluid ejection module includes a flow-path body, a first oxide layer, a membrane, and a second oxide layer. The flow-path body has a first outer surface and an opposing second outer surface and a plurality of flow paths, each flow path extending at least from the first outer surface to the second outer surface. The first oxide layer coats at least an interior surface of each of the flow paths and the first and second outer surfaces of the flow-path body and has a thickness that varies by less than 5% along {100} planes. The membrane has a first outer surface. The second oxide layer is coated on the first outer surface of the membrane and has a thickness that varies by less than 5% along {100} planes and is bonded to the first oxide layer.