Silicon Carbonitride Intermediate Layer for Ink-Resistant Adhesion
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Solution Overview
Problem
The existing liquid ejection heads face issues with adhesion between the substrate and the flow path forming member due to differences in linear expansion coefficients, leading to distortion and separation, especially when using inks that dissolve SiO or SiN adhesion improvement layers, resulting in corrosion and unreliable printing.
Innovation Solution
A liquid ejection head with a silicon carbonitride intermediate layer between the resin layer and the protective layer, which enhances adhesion and resistance to inks that dissolve SiO or SiN, ensuring a strong joined portion and maintaining printing quality over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If SiO or SiN adhesion improvement layers are used between the substrate and flow path forming member, then adhesion is improved, but the layers dissolve when exposed to certain ink ingredients causing separation
Solution Approach 1:
The patent introduces an intermediate layer composed of SiO2, SiN, or SiON between the substrate and the flow path forming member. This intermediate layer acts as a mediator that provides adhesion improvement while being resistant to dissolution by ink ingredients containing bisphosphonic acid or acrylic polymer, thereby resolving the contradiction between adhesion strength and resistance to ink dissolution.
Solution Approach 2:
The patent uses composite material structures where the intermediate layer is formed of specific silicon-based compounds (SiO2, SiN, or SiON) that combine the adhesion properties of SiO/SiN layers with enhanced chemical resistance to ink ingredients, creating a material that simultaneously achieves both adhesion improvement and dissolution resistance.
2Productivity
If the recording element substrate is increased in length to achieve faster print processing, then productivity is improved, but distortion and separation occur due to stress from difference in linear expansion coefficient
Solution Approach 1:
The intermediate layer of SiO2, SiN, or SiON serves as a stress-absorbing mediator between the substrate and flow path forming member. This layer accommodates the differential thermal expansion stress that occurs when the recording element substrate is increased in length for faster printing, preventing distortion and separation while maintaining structural stability.
Solution Approach 2:
The patent changes the material parameters of the intermediate layer to have specific thermal expansion characteristics that match or bridge the difference between the substrate and flow path forming member. By selecting materials with appropriate thermal expansion coefficients, the patent reduces stress accumulation during thermal cycling, enabling longer substrates without distortion.
3Reliability
If ink composition is changed to improve light resistance and gas resistance, then printing quality is improved, but the ink dissolves the adhesion improvement layer causing separation and corrosion
Solution Approach 1:
The intermediate layer of SiO2, SiN, or SiON acts as a chemically resistant mediator that protects the adhesion interface from dissolution by ink ingredients. This layer allows the use of advanced ink compositions with bisphosphonic acid and acrylic polymer for improved light and gas resistance without suffering from adhesion layer dissolution.
Solution Approach 2:
The patent employs composite material strategy where the intermediate layer is formed of silicon-based compounds that provide both adhesion improvement and chemical inertness against specific ink ingredients, enabling the use of high-performance ink formulations without compromising structural integrity.
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 silicon carbonitride intermediate layer provides improved adhesion and anti-liquid properties, preventing separation and corrosion, thus ensuring reliable and long-lasting printing performance.
Implementation Method 1
heating and bubbling ink by a heat-generating resistance element and ejecting, using the bubbling, the ink onto a recording medium
Implementation Method 2
the ink contains an ingredient that dissolves SiO or SiN, it is highly likely that a defect such as separation is caused by dissolution of the adhesion improvement layer
Data Source
AI summary
A liquid ejection head, including: a flow path forming member including a resin layer having an ejection orifice and a flow path formed therein; a substrate including a heat-generating resistance element for ejecting liquid and a protective layer having a portion for covering the heat-generating resistance element, a surface of the portion being exposed to the flow path; and an intermediate layer formed between the resin layer and the protective layer, the intermediate layer including a silicon carbonitride material.