MEMS Inkjet Head Substrate Nesting for Mechanical Protection

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Solution Overview

Problem

In ink jet recording heads, the mechanical damage to the pressure chamber forming substrate is a significant issue due to its larger size compared to the driver substrate, leading to reduced manufacturing yield and quality, especially when the substrate is thinned for increased ejectability and precision.

Innovation Solution

A configuration where the pressure chamber forming substrate is smaller than the driver substrate, with its end portion positioned inside the driver substrate, providing protection and preventing mechanical damage, and a manufacturing method involving stealth dicing to ensure precise alignment and division of substrates for increased productivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the pressure chamber forming substrate is made larger to accommodate high-density nozzle arrangement, then the nozzle density is improved, but the substrate becomes more susceptible to mechanical damage

Engineering Contradiction:

Improvenozzle densityVSAvoidsubstrate mechanical strength

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The pressure chamber forming substrate is nested within the driver substrate, with the former being smaller and positioned inside the boundaries of the latter. This nesting arrangement allows the larger driver substrate to protect the smaller pressure chamber forming substrate from mechanical damage while still accommodating high-density nozzle arrangements.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent transitions from a conventional configuration where substrates are comparable in size to a configuration where the pressure chamber forming substrate is deliberately made smaller and positioned in a nested relationship with the driver substrate. This dimensional change resolves the contradiction by allowing high nozzle density without proportionally increasing substrate vulnerability.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If the pressure chamber forming substrate is thinned to improve ejectability and precision, then the ejection performance is improved, but the substrate becomes more fragile and prone to mechanical damage

Engineering Contradiction:

Improveejection precisionVSAvoidsubstrate mechanical strength

Core Design Contradiction:

Manufacturing precisionVSStrength

Solution Approach 1:

The driver substrate serves as a protective cushion for the thinned pressure chamber forming substrate. By positioning the smaller, thinned substrate within the boundaries of the larger driver substrate, the latter provides mechanical support and protection against damage during handling and operation, enabling the former to be sufficiently thin for high ejection precision.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Quantity of substance

If the pressure chamber forming substrate is made larger for high-density nozzle arrangement, then the nozzle density is improved, but the substrate overhangs from the driver substrate causing handling difficulties

Engineering Contradiction:

Improvenozzle densityVSAvoidsubstrate handling ease

Core Design Contradiction:

Quantity of substanceVSEase of operation

Solution Approach 1:

The pressure chamber forming substrate is nested within the driver substrate boundaries, eliminating overhang and creating a compact, handleable assembly. This nesting configuration maintains high nozzle density while ensuring the entire assembly has a uniform outer boundary defined by the driver substrate, facilitating easy handling during manufacturing and operation.

Inventive Principle:

Principle #7Nested doll (Nesting)

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 durability and manufacturing yield of the ink jet recording heads by preventing mechanical damage to the pressure chamber forming substrate, allowing for thinner and more robust devices with improved ejectability and precision.

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 chamber by driving the piezoelectric element

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS10449764B2MEMS device, liquid ejecting head, liquid ejecting apparatus, manufacturing method of MEMS device, and manufacturing method of liquid ejecting head

Publication Date: 2019.10.22 SEIKO EPSON CORP

AI summary

A MEMS device includes a first substrate; a second substrate that is disposed laminated on the first substrate; and a functional element that is disposed between the first substrate and the second substrate, in which the second substrate is smaller than the first substrate, and in planar view, an end portion of the second substrate is disposed inside an end portion of the first substrate.