Liquid Ejection Head Inner Lead Width Standardization
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Solution Overview
Problem
The existing bonding methods for connecting electric wiring substrates with printing element substrates in liquid ejection heads face instability and increased bonding time due to the mixing of thick leads with large currents and thin leads with small currents, requiring different bonding conditions and multiple tool traversals.
Innovation Solution
The liquid ejection head design includes printing element substrates with multiple connecting terminals and electric wiring substrates featuring inner leads of varying widths, allowing for stable bonding under the same conditions by ensuring all inner leads have the same width, thus enabling sequential bonding without changing tool settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the line width of inner leads is increased to handle larger current, then heat generation is suppressed and reliability is improved, but bonding time increases due to requiring multiple bonding operations with different conditions
Solution Approach 1:
The patent applies local quality by providing different line widths for different functional groups of inner leads. Specifically, leads for logic circuits maintain a first line width, while leads for energy generating elements have a second line width that is larger to handle higher currents. This localized differentiation allows each lead type to be optimized for its specific current requirements while enabling all leads to be bonded under uniform conditions.
2Reliability
If different bonding conditions are used for thick leads and thin leads, then stable bonding is achieved, but device complexity and process complexity increase
Solution Approach 1:
The patent applies homogeneity by making all inner leads have the same thickness, which enables them to be bonded under uniform bonding conditions. This is achieved by providing different line widths in the wiring patterns of the flexible substrate, where the line width is adjusted according to the current requirements of each functional group, but the final lead thickness after formation is standardized. This uniformity simplifies the bonding process while maintaining reliable connections for both logic and energy generating element leads.
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 approach stabilizes the bonding process and significantly reduces bonding time by allowing all inner leads to be bonded under uniform conditions, minimizing tool travel and maintaining reliability across varying current loads.
Implementation Method 1
an inner lead and a corresponding connecting terminal are applied with an ultrasonic wave and a load using a tool
Data Source
AI summary
Provided is a liquid ejection head that makes it possible to achieve both of the stability of bonding and the shortening of a bonding time when bonding an electrical wiring substrate where thick leads applied with large current and thin leads applied with small current are mixed and a printing element substrate. For this purpose, the electrical wiring substrate includes wiring lines having different widths, and each of the wiring lines of the electric wiring substrate and a connecting terminal of the printing element substrate are connected by inner leads whose number corresponds to width of the wiring line.