Liquid Ejection Head Inorganic Sealing Layer
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Solution Overview
Problem
Existing liquid ejection heads face issues with liquid leakage due to insufficient resistance to physical shock and vibration, and challenges in evenly forming the flow path forming member, leading to gaps and detachment from the substrate.
Innovation Solution
A liquid ejection head with a flow path forming member made of inorganic materials, featuring a member that covers the substrate side end part of the inner wall to prevent leakage, formed through a process involving a sacrifice layer and etching to create a flow path mold, ensuring the member covers potential gaps and enhances structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the flow path forming member is thinly formed to achieve desired ejection characteristics, then the ejection performance is improved, but the resistance to physical shock and vibration becomes insufficient
Solution Approach 1:
The flow path forming member is constructed as a composite structure combining a resin base layer with an inorganic material layer. The resin provides shock absorption and flexibility, while the inorganic material layer (formed by CVD or similar processes) provides hardness, chemical resistance, and structural integrity. This composite approach allows the flow path to be thin for good ejection characteristics while maintaining sufficient resistance to physical shock and vibration through the reinforced inorganic layer.
2Ease of manufacture
If the flow path forming member is formed by photolithographic method, then the production process is simplified, but gaps or pinholes are formed leading to liquid leakage
Solution Approach 1:
The flow path forming member is divided into multiple functional layers: a resin base layer formed by photolithography that provides the overall structure and flow path geometry, and an inorganic material layer that provides sealing and defect-free characteristics. By segmenting the structure into these layers with different formation methods, the patent achieves both ease of manufacture (using photolithography for the base) and reliability (using CVD or similar processes for the inorganic sealing layer that prevents pinholes and gaps).
Solution Approach 2:
The patent changes the material parameters and formation process parameters by transitioning from a single-material photolithographic approach to a multi-material approach where an inorganic material layer is deposited over the resin base. This parameter change in material composition and formation process eliminates the pinhole and gap defects inherent in photolithographic single-layer structures while maintaining the manufacturability benefits.
3Strength
If another member is arranged to enhance the strength of the flow path forming member, then the resistance to physical shock is improved, but gaps are easily formed at the contact portion with the substrate
Solution Approach 1:
Instead of uniformly enhancing strength throughout the flow path forming member, the patent applies local quality enhancement by forming an inorganic material layer specifically at critical areas where gaps and pinholes are most likely to form, particularly at the contact portion with the substrate and at the flow path walls. This localized reinforcement approach provides the necessary strength and sealing where needed while avoiding the gap formation issues that occur with uniform reinforcement methods.
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 effectively reduces liquid leakage and improves the long-term reliability of the liquid ejection head by covering substrate side end parts, maintaining ejection characteristics and resistance to detachment and cracking.
Implementation Method 1
the flow path forming member is formed by means of a chemical vapor deposition (CVD) method so as to cover a mold material of the liquid flow path
Data Source
AI summary
A liquid ejection head includes a substrate and a flow path forming member on the substrate, the flow path forming member forming an ejection orifice from which a liquid is ejected and a liquid flow path. The flow path forming member is formed of an inorganic material, contains at least a flow path side wall portion forming a side of the liquid flow path and has a member covering a substrate side end part of an inner wall of the flow path side wall portion.