Liquid Discharge Head Substrate Electrode Plug Configuration
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Solution Overview
Problem
The existing liquid discharge head substrates face issues with uneven electrode plug formation, leading to incomplete coverage by the protective layer, which can result in a potential difference between the electrode plug and the liquid, causing the protective layer to dissolve and reducing the durability of the substrate.
Innovation Solution
The substrate design includes a heat generating resistive element and electrode plugs arranged such that the orthogonal projection of the resistive element overlaps with the electrode plugs, with the electrode plugs' length in one direction being smaller than the resistive element's length and larger in a perpendicular direction, ensuring proper contact and coverage, and a method of manufacturing involving insulating layers, conductive patterns, and a protective layer to enhance durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional electrode plug formation process is used, then the manufacturing process is simple, but the electrode plug surface becomes uneven and coverage by protective layer is incomplete
Solution Approach 1:
The patent applies preliminary action by forming a planarization layer before the protective layer to pre-compensate for surface unevenness. The planarization layer is deposited to fill in the uneven areas of the electrode plug surface, ensuring that the subsequent protective layer can be formed uniformly without exposing any portions of the heat generating resistive element.
2Reliability
If the protective layer coverage is incomplete, then the manufacturing cost is reduced, but electrolysis occurs and durability decreases
Solution Approach 1:
The patent introduces a planarization layer as an intermediary between the electrode plug and the protective layer. This intermediate layer serves as a buffer that compensates for surface unevenness, enabling the protective layer to achieve complete and uniform coverage over the heat generating resistive element, thereby preventing electrolysis and improving durability.
3Manufacturing precision
If the electrode plug is formed with standard dimensions, then the manufacturing is easy, but the protective layer cannot uniformly cover the heat generating resistive element
Solution Approach 1:
The patent solves the coverage uniformity problem by adding another dimension to the structure - a planarization layer deposited over the electrode plug. This additional layer provides the necessary surface compensation without requiring changes to the electrode plug fabrication process itself, maintaining ease of manufacture while achieving uniform protective layer coverage.
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 configuration improves the durability of the liquid discharge head substrate by preventing uneven electrode plug formation and ensuring complete coverage, reducing the risk of electrolysis and enhancing the substrate's operational stability.
Implementation Method 1
a heat generating resistive element arranged above the insulating layer and configured to generate heat energy for discharging a liquid
Implementation Method 2
electrode plugs electrically connecting the heat generating resistive element and the conductive patterns
Implementation Method 3
a liquid such as ink reaches the heat generating resistive element to generate a potential difference between the electrode plug at a positive potential and the liquid at the ground potential during the operation of the heat generating resistive element. Owing to the potential difference, the protective layer is dissolved by an electrolysis operation
Data Source
AI summary
A liquid discharge head substrate is provided. The head substrate comprises a substrate, an insulator arranged above the substrate, conductive patterns arranged in the insulator, a heat generating resistive element arranged above the insulator, a protective layer covering the heat generating resistive element, and electrode plugs configured to connect the heat generating resistive element and the conductive patterns. The heat generating resistive element and the electrode plugs are arranged in contact with each other to overlap each other. A current flows through the heat generating resistive element in a first direction. In the first direction, a length of the electrode plug is smaller than a length of the heat generating resistive element and in a second direction crossing the first direction, a length of the electrode plug is larger than a length of the heat generating resistive element.