Liquid Ejection Head Sealing Structure for Wire Insulation
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Solution Overview
Problem
The adhesiveness of the resin sealing agent between the side surface of the element substrate and the external wire in liquid ejection heads is inadequate, leading to potential peeling and reduced electrical insulation, which affects the longevity of the device.
Innovation Solution
The formation of depressed portions on the substrate surface to enhance the adhesion of the resin sealing agent, ensuring it covers a larger area and improves bonding with the substrate, thereby preventing peeling and enhancing electrical insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resin sealing agent is disposed between the side surface of the element substrate and the external wires to improve electrical insulation, then electrical insulation is improved, but the adhesiveness is inadequate leading to peeling
Solution Approach 1:
The patent applies local quality by creating a depressed portion at a specific location on the side surface of the substrate to enhance local adhesion. The resin sealing agent is concentrated in this depressed region, providing both electrical insulation and improved bonding strength where it is most needed, rather than uniformly distributing the sealing agent across the entire surface.
Solution Approach 2:
The depressed portion introduces a curved surface geometry that increases the surface area and improves the mechanical interlocking between the resin sealing agent and the substrate. This curvature allows the resin to better conform to the substrate surface, enhancing adhesion and preventing peeling while maintaining electrical insulation.
2Reliability
If the resin sealing agent is applied to cover the electrical connection portion, then electrical insulation is achieved, but the resin peels due to insufficient adhesion
Solution Approach 1:
The depressed portion is pre-formed on the substrate surface before applying the resin sealing agent. This preliminary structural modification prepares the surface to enhance resin adhesion from the outset, ensuring that when the resin is applied, it immediately achieves better bonding without subsequent peeling, thereby extending device longevity while maintaining electrical insulation.
Solution Approach 2:
The curved surface of the depressed portion allows the resin sealing agent to better conform and bond to the substrate, creating a more durable electrical insulation layer that resists peeling over time, thus extending the operational life of the device.
3Ease of manufacture
If a flat side surface is used for substrate sealing, then manufacturing is simple, but the sealing agent adhesion is insufficient
Solution Approach 1:
Rather than making the entire substrate surface complex, the patent introduces a localized depressed portion that provides enhanced adhesion only where the resin sealing agent is applied. This approach maintains the simplicity of manufacturing the overall substrate while locally improving the critical bonding area.
Solution Approach 2:
The depressed portion introduces a curved surface feature that significantly improves resin adhesion through increased surface area and mechanical interlocking, while requiring minimal additional manufacturing steps compared to a completely complex surface structure.
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 improved adhesiveness extends the life of the liquid ejection head by preventing resin peeling and maintaining electrical insulation, thus ensuring reliable operation.
Implementation Method 1
the sealing agent enters the depressed portion to cover at least a part of the side surface of the substrate
Data Source
AI summary
A liquid ejection head is used which has: a substrate provided with an ejection port for a liquid, an energy generating element for generating an energy for ejecting the liquid, a liquid inflow port for receiving supply of the liquid, a pad electrode, and an internal wire for connecting the pad electrode and the energy generating element; and an external wire connected to the pad electrode of the substrate, wherein. a depressed portion is provided on the side surface of the substrate, and at least the pad electrode, a partial region. which is closer to the pad electrode, and the region, which includes the depressed portion of the side surface of the substrate, of the external wire are sealed with a resin sealing agent.