MEMS Liquid Ejecting Head Substrate Protection
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Solution Overview
Problem
In ink jet recording heads, the mechanical damage to the pressure generating chamber forming substrate is a significant issue due to its larger size compared to the driver substrate, leading to reduced manufacturing yield and quality, and the challenge of electrical connection at high density of piezoelectric elements.
Innovation Solution
The use of two substrates of the same size, where the second substrate with the pressure generating chamber is protected by the first substrate, and an adhesive layer encloses the functional element, preventing mechanical damage and ensuring reliable electrical connection through bump electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the pressure generating chamber forming substrate is made larger to accommodate high-density nozzles and thinning for improved ejection precision, then ejection precision and nozzle density are improved, but mechanical strength decreases and mechanical damage occurs
Solution Approach 1:
The patent combines a pressure generating chamber forming substrate (second substrate) with a driver substrate (first substrate) to create a composite structure. The driver substrate provides mechanical strength while the pressure generating chamber forming substrate enables high-density nozzles and precise ejection, resolving the contradiction between mechanical strength and ejection precision through material and structural composition.
Solution Approach 2:
The pressure generating chamber forming substrate is disposed on and integrated with the driver substrate, forming a nested layered structure. This allows the thinner pressure generating chamber forming substrate to benefit from the mechanical support of the driver substrate, maintaining both high ejection precision and adequate mechanical strength.
2Quantity of substance
If the pressure generating chamber forming substrate is made larger than the driver substrate to achieve high-density nozzle arrangement, then nozzle density is improved, but mechanical damage occurs due to overhanging ends
Solution Approach 1:
The patent intentionally designs the driver substrate to extend beyond the pressure generating chamber forming substrate in certain regions, creating an asymmetric configuration. This asymmetric extension provides mechanical support to the overhanging portions of the pressure generating chamber forming substrate, preventing mechanical damage while maintaining high nozzle density.
Solution Approach 2:
The driver substrate acts as a pre-established mechanical support structure that cushions and protects the pressure generating chamber forming substrate from mechanical damage before any damage can occur. This prior cushioning through structural design prevents reliability issues while enabling high-density nozzle arrangements.
3Manufacturing precision
If piezoelectric elements are disposed at high density to improve ejection precision, then ejection precision is improved, but electrical connection becomes difficult
Solution Approach 1:
The patent merges the piezoelectric elements directly onto the driver substrate, integrating the actuation function with the driving circuit substrate. This combination simplifies electrical connection by reducing the number of separate components and connection interfaces, while maintaining high-density arrangement for precise ejection.
Solution Approach 2:
The driver substrate serves as an intermediary that provides both mechanical support and electrical connection pathways for the piezoelectric elements. This intermediary structure facilitates simplified electrical connection while enabling the high-density arrangement of piezoelectric elements required for precise ejection.
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 enhances the mechanical strength of the first substrate, reduces mechanical damage to the second substrate, and improves the reliability and yield of the ink jet recording head by ensuring stable operation of the piezoelectric element and efficient ink ejection.
Implementation Method 1
a functional element (piezoelectric element) that is provided on one surface side of the flow path forming substrate, generates pressure variation in the liquid within the pressure generating chamber by driving the piezoelectric element
Implementation Method 2
an adhesive, is blocked from the atmosphere, and moisture-proofing of the piezoelectric element is achieved
Data Source
AI summary
A MEMS device includes a first substrate and a second substrate that is disposed laminated on the first substrate and has a piezoelectric element on the first substrate side, in which the first substrate and the second substrate are substantially the same size, and in planar view, an end of the first substrate and an end of the second substrate are disposed at substantially the same position.