Liquid Ejection Head Buried Wiring and Connection Structure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing liquid ejection heads face challenges in reducing wiring resistance and ensuring reliable connections between wirings and external terminals, particularly at high densities, due to limitations in photolithography methods and the difficulty in connecting buried wirings to terminal portions.
Innovation Solution
A liquid ejection head design featuring a buried wiring in a groove on the substrate, covered by a connection wiring with a recessed portion, where the connection wiring and terminal portion are positioned to overlap with the buried wiring, allowing for reduced resistance and reliable connection without the need for additional processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wiring is provided in a groove of a wiring substrate to reduce electric resistance, then the electric resistance value is reduced, but the wiring surface becomes lower than the substrate surface making connection to external terminals difficult
Solution Approach 1:
The patent transitions from a two-dimensional surface wiring to a three-dimensional structure by creating a groove and filling it with wiring material. The connection wiring then extends from the groove upward to connect with external terminals, utilizing the vertical dimension to resolve the height difference problem while maintaining the low-resistance buried wiring configuration.
2Reliability
If the wiring substrate is made large to accommodate wider wirings for reduced resistance, then the electric resistance value is reduced, but the device size increases
Solution Approach 1:
Instead of increasing the substrate area to accommodate wider wirings, the patent utilizes the vertical dimension by creating grooves and extending connection wirings upward. This allows for reduced electric resistance through optimized wiring paths without increasing the horizontal footprint of the device.
3Area of stationary object
If wirings are disposed at high density to reduce substrate size, then the device size is reduced, but connection conditions between wiring and external terminals are restricted
Solution Approach 1:
The patent employs vertical extension of connection wirings from buried grooves to external terminals, creating multiple connection points and flexible routing options. This three-dimensional wiring approach maintains high density while improving connection adaptability by allowing terminals to be positioned at different heights and locations.
Data Source
AI summary
In a plan view from a perpendicular direction to a surface of a wiring substrate on which a wiring is provided, a buried wiring, a connection wiring, and a terminal portion of an external wiring are formed at an overlapping position, in which a recessed portion is provided at a position corresponding to the buried wiring on a surface of the connection wiring on an opposite side to the wiring substrate, and in which, in a direction intersecting an extension direction of the wiring on the surface of the wiring substrate on which the wiring is provided, a width of the connection wiring is larger than a width of the buried wiring, a width of the terminal portion of the external wiring is larger than a width of the recessed portion, and the terminal portion is provided across the recessed portion of the connection wiring.