Liquid Ejecting Head Protection Film Atomic Layer Deposition

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Solution Overview

Problem

In liquid ejecting heads, such as inkjet recording heads, electrical contact between lead electrodes and wiring substrates is often hindered by protection films, leading to issues like liquid leakage, ejection failure, and substrate separation due to etching and ink exposure.

Innovation Solution

A liquid ejecting head design featuring a stack of substrates with a protection film that prevents etching and leakage, including a laminate with electrodes connected to a wiring substrate and a protection film formed using atomic layer deposition to cover inner walls of flow paths and surfaces, ensuring electrical connection without impeding diaphragm movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a protection film is formed on lead electrodes, then etching resistance and liquid leakage prevention are improved, but electrical contact between lead electrodes and wiring substrate deteriorates

Engineering Contradiction:

Improveetching resistanceVSAvoidelectrical contact failure

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary action by forming the protection film after establishing electrical connections through through-holes. The through-holes are created first to ensure electrical contact, then the protection film is deposited to provide etching resistance. This sequence resolves the contradiction by prioritizing electrical connection establishment before applying protective coverage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The protection film structure implements local quality by having different coverage characteristics in different regions. The film covers the inner walls of flow paths and surfaces where etching protection is needed, while leaving through-holes open to maintain electrical contact. This spatial differentiation allows simultaneous achievement of etching resistance and electrical conductivity.

Inventive Principle:

Principle #3Local quality

2Reliability

If a thick protection film is formed, then etching prevention is improved, but diaphragm deformation and liquid ejection performance deteriorate

Engineering Contradiction:

Improveetching preventionVSAvoidejection failure

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies parameter changes by optimizing the protection film thickness to a specific range that balances etching protection and diaphragm deformation. The film thickness is controlled to be sufficient for etching resistance but thin enough to allow adequate diaphragm movement for liquid ejection.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If protection film is formed before electrical connection, then manufacturing process simplicity is improved, but electrical contact reliability deteriorates

Engineering Contradiction:

Improveprocess simplicityVSAvoidelectrical contact reliability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies preliminary action by forming the protection film after establishing electrical connections through through-holes. The through-holes are created first to ensure electrical contact, then the protection film is deposited to provide etching protection. This sequence resolves the contradiction by prioritizing electrical connection establishment before applying protective coverage.

Inventive Principle:

Principle #10Preliminary action

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

The solution effectively prevents etching and leakage, maintains electrical contact, and ensures reliable operation by using a thin, high-density protection film that enhances ink resistance without obstructing the diaphragm's deformation, thus improving the stability and performance of the liquid ejecting head.

Implementation Method 1

The protection film may prevent or reduce etching of the substrates by liquid in flow paths in the substrates

Methodology Applied

Scientific EffectPhysical barrier protection:

Implementation Method 2

The protection film may also prevent or reduce liquid leakage, liquid ejection failure, and/or separation of the substrates

Methodology Applied

Scientific EffectSealing:

Implementation Method 3

a protection film formed using atomic layer deposition to cover inner walls of flow paths and surfaces

Methodology Applied

Scientific EffectAtomic layer deposition:

Data Source

PatentUS10850514B2Liquid ejecting head and method for manufacturing liquid ejecting head

Publication Date: 2020.12.01 BROTHER KOGYO KK

AI summary

A liquid ejection head manufacturing method comprising a step of forming a laminate, a step of connecting and a step of forming a protection film. The laminate includes electrodes and flow paths of liquid. The step of connecting is connecting terminals of a wiring substrate to terminals of the electrodes. The protection film is formed using atomic layer deposition, on a surface of the laminate defining the flow paths after connecting the terminals.