Liquid Ejection Head Manufacturing via Layered Water Absorption
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Solution Overview
Problem
The existing methods for manufacturing liquid ejection heads, such as those described in Japanese Patent Laid-Open No. 2009-1003, result in long development times that can lead to solvent cracks due to the developer dissolving resin and penetrating exposed portions, causing wrinkles on the surface and affecting precise ink ejection.
Innovation Solution
A method involving an intermediate layer between the substrate and the flow channel member, with specific water absorption relationships between the intermediate layer, the flow channel member, and the ejection opening member, where the water absorption of the intermediate layer is greater than or equal to the exposed portions of the first and second photosensitive resin layers, and the second layer's absorption is less than the first, to control developer penetration and reduce solvent cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the development time is extended to ensure complete removal of unexposed resin, then the manufacturing precision deteriorates due to solvent cracks and wrinkles forming on the surface
Solution Approach 1:
The patent applies different water absorption properties to different layers (intermediate layer with higher water absorption, flow channel member with lower water absorption) to create local quality differences. This allows the developer to be absorbed preferentially by the intermediate layer, preventing excessive penetration into the flow channel member and ejection opening member, thus avoiding solvent cracks while ensuring complete development.
Solution Approach 2:
The intermediate layer with high water absorption acts as a cushioning layer that absorbs the developer before it can penetrate deeply into the exposed resin portions. This beforehand cushioning prevents the harmful effects of excessive developer penetration, such as solvent cracks and surface wrinkles, while still allowing complete removal of unexposed resin.
2Productivity
If the developer penetrates deeply to remove all unexposed resin, then the productivity improves, but the surface quality deteriorates due to wrinkle formation
Solution Approach 1:
The intermediate layer serves as an intermediary between the substrate and the photosensitive resin layers. It mediates the interaction between the developer and the exposed resin by absorbing the developer preferentially, thus preventing direct excessive contact between the developer and the exposed portions of the photosensitive resin layers, avoiding surface wrinkles while ensuring complete development.
3Ease of manufacture
If the water absorption of all layers is made uniform, then the ease of manufacture improves, but the manufacturing precision deteriorates due to uncontrolled developer penetration
Solution Approach 1:
The patent deliberately creates non-uniform water absorption properties across different layers. The intermediate layer has higher water absorption than the flow channel member and ejection opening member. This local quality differentiation enables precise control over developer penetration, ensuring that the developer is absorbed by the intermediate layer first, preventing excessive penetration into the functional layers while maintaining 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
This approach reduces solvent cracks and enables precise ink ejection by controlling the water absorption of the resin layers, ensuring the developer does not excessively swell the exposed portions, thereby maintaining the integrity of the ejection openings and improving the manufacturing efficiency.
Implementation Method 1
selectively exposing the first photosensitive resin layer to light, thereby curing the portion of the first photosensitive resin layer defining the flow channel member
Implementation Method 2
selectively exposing the second photosensitive resin layer to light, thereby curing the portion of the second photosensitive resin layer defining the ejection opening member
Data Source
AI summary
A method for manufacturing a liquid ejection head includes selectively exposing a first photosensitive resin layer to light, thereby curing the portion of the first photosensitive resin layer defining a flow channel member; forming a second photosensitive resin layer on the first photosensitive resin layer; selectively exposing the second photosensitive resin layer to light, thereby curing the portion of the second photosensitive resin layer defining an ejection opening member; and removing the unexposed portions of the first and the second photosensitive resin layer at one time with a developer. Before removal with the developer, the water absorption W of the intermediate layer, the water absorption W1 of the exposed portion of the first photosensitive resin layer, and the water absorption W2 of the exposed portion of the second photosensitive resin layer satisfy the relationship W≥W1>W2.