Liquid Ejection Head Terminal Structure for Substrate Reliability
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Solution Overview
Problem
The structural reliability of liquid ejection heads is compromised due to the thinning of substrates with eave-shaped terminals, which are prone to breakage, and ionic migration occurs at densely disposed electric wirings, affecting electric reliability.
Innovation Solution
A liquid ejection head design with a first substrate having ejection ports and a second substrate joined to its opposite surface, featuring projecting areas with terminals, supported by a reinforcement member and frame configuration to enhance structural integrity and reduce wiring density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electric wirings are densely disposed on the substrate to supply power to densely arranged energy generation elements, then high resolution imaging is achieved, but ionic migration occurs at the electric wiring parts lowering electric reliability
Solution Approach 1:
The patent transitions terminal arrangement from a planar 2D layout to a 3D protruding structure. Terminals are formed to protrude from the substrate surface, creating additional spatial dimension for wire bonding. This dimensional change allows electric connections to be made at elevated positions, reducing wiring density on the substrate plane while maintaining connection to densely packed energy generation elements, thereby preventing ionic migration while preserving high-resolution imaging capability
2Ease of operation
If terminals are disposed at eave-shaped portions to expose electric connection terminals, then electric connection is enabled, but the substrate becomes thin and prone to breakage
Solution Approach 1:
The patent performs preliminary reinforcement by forming protruding terminals with sufficient structural support before the substrate becomes vulnerable. The terminal structure includes reinforced portions that maintain substrate integrity during subsequent handling and wire bonding operations. This preliminary structural preparation prevents breakage while enabling reliable electric connection, addressing both requirements simultaneously
3Ease of operation
If substrates are thinned to form eave-shaped terminals, then terminal exposure for connection is achieved, but structural reliability is compromised due to breakage susceptibility
Solution Approach 1:
The patent employs composite structural design where terminals are formed as integrated structures combining conductive material with reinforced support portions. The terminal structure acts as a composite element that provides both electrical connectivity and mechanical reinforcement, preventing substrate breakage while maintaining terminal exposure for reliable electric connection
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 design improves the structural reliability of the liquid ejection head by reinforcing vulnerable eave-shaped portions and reducing the risk of breakage, while maintaining high ejection performance and electric connectivity.
Implementation Method 1
an energy generation element that generates an energy for ejecting the liquid in the liquid chamber through the ejection port
Data Source
AI summary
To improve the structural reliability of a liquid ejection head, the liquid ejection head includes a first substrate having ejection ports, liquid chambers, and energy generation elements, and a second substrate joined to a second surface of the first substrate situated opposite to its first surface. The first substrate includes projecting areas projecting from end portions of the second substrate in a planar direction perpendicular to a first-axis direction (z-axis direction). Terminals to be electrically connected to the energy generation elements are provided at the second surfaces of the projecting areas. A support member is joined to the first surface of the first substrate, has an opening at a position opposed to where the ejection ports are formed, and is fixed to the frame.