Embedded Wire Configuration for Liquid Ejecting Head
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Solution Overview
Problem
Existing liquid ejecting heads face challenges in reducing wire resistance and area without increasing the size of the sealing plate, especially as the number of nozzles increases, leading to difficulties in maintaining electrical characteristics and preventing wire breakage due to environmental changes and migration.
Innovation Solution
Embedding wires within the wiring substrate allows for increased cross-sectional area without widening the wire, reducing resistance and improving layout flexibility, while direct connection to driver IC bump electrodes minimizes wire distance and resistance, and using electroplating for conductive material formation simplifies manufacturing and enhances reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the width of the wire is increased to lower the resistance, then the resistance of the wire decreases, but the wire area becomes large making it difficult to decrease the resistance without changing the size of the sealing plate
Solution Approach 1:
The wire is embedded within the sealing plate, transitioning from a surface-level configuration to a three-dimensional embedded structure. This allows the wire cross-sectional area to be increased vertically within the plate thickness, reducing resistance without increasing the planar wire width or sealing plate footprint.
Solution Approach 2:
The wire is nested within the sealing plate structure, with the wire positioned inside the plate body and connected to bump electrodes on the surface. This nesting arrangement enables the wire to occupy internal space of the sealing plate, achieving lower resistance through increased cross-sectional area while maintaining compact external dimensions.
2Productivity
If the number of nozzles is increased to achieve nozzle densification, then the productivity increases, but the electrical power supplied to the driver IC increases requiring lower wire resistance
Solution Approach 1:
By embedding the wire within the sealing plate and utilizing the thickness dimension, the wire cross-sectional area is increased without increasing the planar footprint. This enables the wire to handle higher electrical power demands resulting from increased nozzle counts while maintaining the compact sealing plate size required for high-density nozzle arrangements.
3Ease of manufacture
If the wire is formed on the surface of the sealing plate, then the manufacturing is simple, but the wire is susceptible to environmental changes and migration causing breakage
Solution Approach 1:
The wire is nested within the sealing plate structure, surrounded by the plate material that provides mechanical support and environmental protection. This embedded configuration shields the wire from external environmental factors and prevents migration, thereby enhancing reliability while the wire maintains its electrical connection function.
Solution Approach 2:
The sealing plate material surrounding the embedded wire provides beforehand cushioning and protection against environmental changes and mechanical stress. This protective structure prevents wire breakage due to migration or environmental factors before they can occur, ensuring long-term reliability.
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 effectively decreases wire resistance and area, improves reliability by suppressing changes in electrical characteristics and preventing breakage, and reduces manufacturing costs, resulting in a high-reliability liquid ejecting head.
Implementation Method 1
forming, by electroplating, the conductive material on the inner wall of the recessed portion
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A liquid ejecting head and a method of manufacturing the liquid ejecting head are provided. The liquid ejecting head has a pressure-chamber-forming substrate that includes a plurality of piezoelectric elements and that is connected to a first surface of a sealing plate, a driver IC that outputs signals that drive the piezoelectric elements and that is provided on a second surface of the sealing plate that is on the opposite side to the first surface, and a power supply wire that supplies electrical power to the piezoelectric elements, that is formed in the second surface of the sealing plate, and that has at least one portion thereof embedded in the sealing plate and a surface thereof exposed on the second surface side.