Fluid-Ejection Nozzle Manufacturing via Wafer Segmentation
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Solution Overview
Problem
Existing manufacturing methods for fluid-ejection devices using piezoelectric technology are costly and require high precision, with limited freedom of action due to the coupling of multiple wafers and incompatibility with certain adhesive materials, and face challenges in forming anti-wetting coatings around the nozzle.
Innovation Solution
A manufacturing method involving the bonding of three wafers processed using micromachining technologies for MEMS devices, where the nozzle is formed on a separate wafer before assembly, allowing for the use of a wide range of micromachining technologies and the formation of a hydrophilic coating within the nozzle, reducing misalignment risks and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If multiple wafers are coupled via gluing or bonding to manufacture fluid-ejection devices, then the device can be assembled with pre-processed parts, but the manufacturing cost increases and manufacturing precision requirements become more stringent
Solution Approach 1:
The device is divided into three separate wafers that are processed independently and then coupled together. Each wafer can be manufactured and processed separately with standard micromachining techniques, avoiding the need for complex high-precision alignment during manufacturing. The segmentation allows each component to be optimized independently while simplifying the overall manufacturing process.
Solution Approach 2:
The wafers are pre-processed with all necessary features (nozzles, chambers, piezoelectric actuators) before coupling. This preliminary processing eliminates the need for post-assembly modifications and reduces alignment requirements during coupling, as all critical features are already in place on each wafer.
2Ease of manufacture
If multiple wafers are coupled via gluing or bonding, then the device can be assembled, but the device thickness increases
Solution Approach 1:
The coupling between wafers is achieved using thin adhesive layers that bond the wafers together while minimizing the added thickness. The adhesive films are applied as thin layers that provide sufficient bonding strength without significantly increasing the overall device thickness, thus maintaining a compact final product.
3Stability of the object's composition
If wafers are coupled together before nozzle formation, then the stack structure is established early, but freedom of action in processing is limited and anti-wetting coating formation becomes inconvenient
Solution Approach 1:
The nozzle features and anti-wetting coatings are formed on the wafers before coupling. This preliminary action allows the use of various micromachining techniques and coating processes that would be difficult or impossible to apply after the wafers are bonded together, thereby maintaining processing flexibility while still achieving a stable final structure.
4Manufacturing precision
If standard micromachining technologies are used on coupled wafers, then manufacturing precision can be maintained, but certain adhesive materials become incompatible due to high-temperature processes or solvents
Solution Approach 1:
By segmenting the manufacturing process into separate wafer processing and coupling stages, the patent allows standard micromachining processes to be applied to each wafer independently before coupling. This segmentation protects the adhesive materials from exposure to high-temperature processes or solvents that would occur during post-coupling processing, thereby expanding adhesive material compatibility while maintaining manufacturing precision.
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
This approach enables the production of fluid-ejection devices with improved wettability and reduced manufacturing costs by forming the nozzle on a separate wafer before assembly, enhancing the manufacturing process's efficiency and flexibility.
Implementation Method 1
A first wafer (2) including a substrate (11) is processed for forming thereon one or more piezoelectric actuators (3), which are designed to be driven for generating a deflection of a membrane (7)
Implementation Method 2
A third wafer (8) is processed to form holes (13) for ejection of the fluid (6) (nozzles)... formation of a hydrophilic coating within the nozzle
Data Source
AI summary
A method for manufacturing a device for ejecting a fluid, including producing a nozzle plate including: forming a first nozzle cavity, having a first diameter, in a first semiconductor body; forming a hydrophilic layer at least in part in the first nozzle cavity; forming a structural layer on the hydrophilic layer; etching the structural layer to form a second nozzle cavity aligned to the first nozzle cavity in a fluid-ejection direction and having a second diameter larger than the first diameter; proceeding with etching of the structural layer for removing portions thereof in the first nozzle cavity, to reach the hydrophilic layer and arranged in fluid communication the first and second nozzle cavities; and coupling the nozzle plate with a chamber for containing the fluid.