Liquid Ejecting Head Stacked Wiring Substrate
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Solution Overview
Problem
Existing liquid ejecting heads face challenges in minimizing wiring resistance and heat generation due to high resistance in the wirings, leading to waveform blunting of driving signals.
Innovation Solution
The configuration of the liquid ejecting head includes a wiring substrate with a base body portion between the flow path formation portion and the driving circuit, featuring signal and power supply wirings with a larger number of conductive layers on one side of the input terminal compared to the other, reducing wiring resistance and heat generation by utilizing stacked-layer and penetration wirings for efficient signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wirings are formed on the driving circuit substrate with conventional configuration, then the device structure is simple, but the wiring resistance is high causing heat generation and waveform blunting
Solution Approach 1:
The patent transitions from planar wiring configuration to three-dimensional stacked-layer wiring configuration. Multiple wiring layers are arranged vertically with penetration wirings connecting different layers, effectively utilizing the Z-direction (thickness direction) to reduce current path length and wiring resistance while maintaining a compact footprint.
Solution Approach 2:
The patent implements nested wiring structures where multiple wiring layers are stacked within each other, with penetration wirings passing through intermediate layers. This nesting approach allows signals to be transmitted through multiple conductive paths in parallel, reducing overall resistance without significantly increasing the lateral footprint.
2Loss of energy
If the number of wirings in the second portion is increased to reduce resistance, then wiring resistance and heat generation are reduced, but the wiring substrate becomes more complex
Solution Approach 1:
The signal wiring is divided into multiple segments arranged in parallel (first wiring, second wiring, third wiring in the second portion). This segmentation creates multiple current paths, reducing overall resistance and heat generation. Each segment can be independently optimized for its specific function.
Solution Approach 2:
The patent employs composite wiring structures combining different materials and configurations across multiple layers. The stacked-layer design integrates various conductive materials with different properties to optimize both electrical performance and thermal management, reducing heat generation through distributed current paths.
Data Source
AI summary
A liquid ejecting head includes a driving circuit configured to output a driving pulse; and a wiring substrate including a base body portion disposed between a flow path formation portion and the driving circuit, and a signal wiring formed on the base body portion and configured to transmit a driving signal for use in generation of the driving pulse by the driving circuit to the driving circuit from an input terminal. The signal wiring includes a first portion overlapping, in a plan view, at least one coupling terminal included in the driving circuit and coupled to the signal wiring, and a second portion located on the side of the input terminal when seen from the first portion, and the total number of wirings constituting the second portion is larger than the total number of wirings constituting the first portion.