Liquid Ejecting Head Through Electrode Wiring
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Solution Overview
Problem
Existing ink jet recording heads face challenges with high manufacturing costs and defective connections due to dense wiring patterns and extensive wire bonding, leading to increased size and reliability issues.
Innovation Solution
A liquid ejecting head design featuring a passage-forming substrate with integrated pressure-generating elements and an IC chip, where the IC chip includes a semiconductor substrate with a driver circuit and through electrodes for direct electrical connection to the pressure-generating elements, simplifying the wiring structure and reducing the risk of defective connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire bonding is used to connect driver IC and wiring pattern, then electrical connection is achieved, but the area required for bonding wire extension increases, leading to increased head size
Solution Approach 1:
The patent merges the electrical connection function into the diaphragm structure itself by forming through-holes directly in the diaphragm to expose electrode patterns. This eliminates the need for separate wire bonding areas, as the electrical connection is integrated within the diaphragm's own structure, thereby reducing the overall head area required for bonding operations.
Solution Approach 2:
The patent transitions from planar wire bonding connections to three-dimensional through-hole connections in the diaphragm. By drilling through-holes vertically through the diaphragm layer, the electrical connection is established in the thickness dimension rather than requiring additional planar area for wire routing and bonding.
2Productivity
If high density wiring pattern is used on driver IC, then electrical connection to pressure-generating chambers is achieved, but manufacturing precision requirements increase and adjacent wires may short-circuit
Solution Approach 1:
The patent extracts the electrical connection function from the driver IC's surface wiring patterns and relocates it to through-holes in the diaphragm. This separation allows the driver IC to use standard, less demanding wiring patterns while the critical high-precision connections are made through the diaphragm's through-holes, which can be formed using precise drilling techniques independent of the IC's wiring density.
Solution Approach 2:
The diaphragm acts as an intermediary structure between the driver IC and the pressure-generating chambers. Instead of directly routing high-density wires from the IC to the chambers, the diaphragm's through-holes serve as precise intermediaries that connect the electrode patterns on the IC to the pressure-generating chambers, thereby mediating the connection and reducing the precision requirements on the IC's wiring patterns.
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 reduces manufacturing costs, prevents defective connections, and enhances the reliability and compactness of the liquid ejecting head by allowing easy and reliable electrical connection between the driver circuit and pressure-generating elements.
Implementation Method 1
a piezoelectric element is provided on a surface of the diaphragm, and the ink droplet is ejected by displacement of the piezoelectric element
Implementation Method 2
The through electrode penetrates through the semiconductor substrate. The through electrode is connected to the second pad
Data Source
AI summary
A liquid ejecting head includes a passage-forming substrate, a plurality of pressure-generating elements, and an IC chip. The passage-forming substrate has a nozzle opening, and a pressure-generating chamber communicating with the nozzle opening. The plurality of pressure-generating elements are provided on a surface of the passage-forming substrate with a diaphragm interposed therebetween. The pressure-generating elements have electrodes and cause pressure change in the pressure-generating chamber. The IC chip is mounted on the surface of the passage-forming substrate with the pressure-generating elements. In this liquid ejecting head, the electrodes of the pressure-generating elements include individual electrodes, and at least the individual electrodes are electrically connected to the driver circuit via the through electrode.