Multilayer Element Substrate Wiring for Inkjet Printheads
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Solution Overview
Problem
Inkjet printheads face issues with voltage drops and overheating due to concurrent heater operation, leading to wire breaks and subsequent electric erosion, which affects discharge stability and image quality.
Innovation Solution
A multilayer structured element substrate with individual wiring connections between heaters and common wiring, using barrier metal layers in through-holes to prevent the spread of electric erosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a common wiring is made thick and wide to reduce resistance, then voltage drop is reduced, but the wiring becomes more susceptible to electric erosion spread
Solution Approach 1:
The patent segments the wiring structure into multiple layers: a lower wiring layer containing the common wiring, and an upper wiring layer containing individual heater wirings. This segmentation isolates the common wiring from direct exposure to ink and electric erosion, while still enabling effective power distribution to all heaters through the multi-layer configuration.
Solution Approach 2:
The patent transitions from a single-plane wiring layout to a three-dimensional multilayer structure. By stacking wiring layers vertically and using through-holes for inter-layer connections, the design reduces the electrical path length and resistance in the common wiring while protecting it from horizontal spread of electric erosion in the ink-exposed plane.
2Object-affected harmful factors
If individual wiring connections are used between heaters and common wiring, then electric erosion spread is suppressed, but wiring complexity increases
Solution Approach 1:
The patent merges multiple wiring functions into a coordinated multilayer system. The lower layer handles common power distribution, while the upper layer manages individual heater connections. Through-holes provide vertical interconnections, combining horizontal and vertical wiring paths into an integrated structure that reduces electric erosion risk without excessive complexity.
Solution Approach 2:
The upper wiring layer acts as an intermediary between the common wiring in the lower layer and the heater elements. This intermediate layer of individual wirings isolates the common wiring from direct contact with ink and potential electric erosion paths, while still enabling effective power delivery to all heaters through the structured multi-layer arrangement.
3Reliability
If wiring is exposed to ink at the time of wire break, then electric erosion occurs, but making wiring thicker to prevent break increases resistance
Solution Approach 1:
The patent applies different wiring configurations to different functional requirements: the common wiring in the lower layer is optimized for low resistance and high current carrying capacity, while the individual heater wirings in the upper layer are optimized for direct heater connection and isolation from ink exposure. This local differentiation allows each wiring segment to be optimized for its specific function without compromise.
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 suppresses the spread of electric erosion, maintaining discharge stability and preventing collective malfunction of heaters, thereby enhancing image quality.
Implementation Method 1
a multilayer structured element substrate is provided. A lower wiring layer including a common wiring connected to a plurality of heaters, and an upper wiring layer including an individual wiring individually connected to each heater are formed. The individual wiring is connected to the common wiring via a through-hole
Data Source
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AI summary
To suppress the progress of metal dissolution by ink when wire break of a wiring to a heater occurs, in an element substrate (700), according to the present invention, for example, which is used in an inkjet printhead (3), each of heaters (350) integrated in the element substrate is connected to an individual wiring (132) via a first through-hole (330, 340) penetrating an insulation layer (230, 240), and further connected to a common wiring (131) from the individual wiring via a wiring (121) formed in another wiring layer (120) via a second through-hole (320) penetrating an insulation layer (220). The individual wiring and the common wiring are formed in the same wiring layer, and an aspect ratio of the second through-hole is lower than an aspect ratio of the first through-hole.