Liquid Ejection Head Substrate Segmentation for Crack Prevention

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Solution Overview

Problem

The existing method for manufacturing liquid ejection heads using silicon ejection port members on a substrate with a different material causes stress due to thermal expansion differences, leading to defects like cracks in the substrate.

Innovation Solution

A method that forms ejection port members on a substrate, includes hardening the material through heat treatment, and creates a separation groove before hardening to prevent defect propagation, enhancing the quality of the liquid ejection heads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If ejection port members are formed with a material different from the substrate (e.g., silicon on different substrate), then the ejection port members can be formed with appropriate material properties, but stress due to thermal expansion difference causes defects such as cracks in the substrate

Engineering Contradiction:

Improvequality of liquid ejection headVSAvoidstress and defects in substrate

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The substrate is divided into multiple independent regions by forming separation grooves between adjacent liquid ejection heads. This segmentation prevents stress and defects from propagating across the entire substrate, isolating each ejection head region to maintain structural integrity despite using different materials for ejection port members and substrate.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Separation grooves are formed in the substrate before the ejection port members are attached and before heat treatment processes. This preliminary action ensures that stress relief paths exist before thermal expansion differences can cause damage, preventing crack propagation in advance.

Inventive Principle:

Principle #10Preliminary action

2Strength

If heat treatment is performed to harden the ejection port members, then the material strength is improved, but thermal expansion differences cause stress that can propagate defects across the substrate

Engineering Contradiction:

Improvehardness of ejection port membersVSAvoidthermal stress in substrate

Core Design Contradiction:

StrengthVSStress or pressure

Solution Approach 1:

The substrate is segmented into independent regions by separation grooves, which act as stress barriers during heat treatment. This allows each region to undergo thermal expansion independently, preventing stress accumulation and defect propagation across the entire substrate while still achieving the desired hardening of ejection port members.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Separation grooves are created before heat treatment to establish stress management pathways in advance. This ensures that when thermal stress occurs during subsequent hardening processes, the pre-formed grooves already provide channels to prevent crack propagation.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If the substrate is processed as a single unit, then manufacturing efficiency is maintained, but defects can propagate across multiple liquid ejection heads

Engineering Contradiction:

Improvemanufacturing efficiencyVSAvoiddefect propagation prevention

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The substrate is designed with separation grooves that divide it into multiple independent regions for individual liquid ejection heads. This segmentation allows the substrate to be processed as a single unit for manufacturing efficiency, while the grooves ensure that any defects remain localized to individual regions and cannot propagate to other heads.

Inventive Principle:

Principle #1Segmentation

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 approach effectively prevents the propagation of defects such as cracks in the substrate, improving the quality and reliability of the liquid ejection heads by forming the separation groove before the stress-inducing heat treatment process.

Implementation Method 1

The step of forming the ejection port members includes the step of hardening a material constituting the ejection port members by heat treatment

Methodology Applied

Scientific EffectHeat treatment: Heat Treatment

Implementation Method 2

forming a separation groove in the substrate to separate the substrate for each liquid ejection head

Methodology Applied

Scientific EffectPhysical barrier effect: Physical Containment

Implementation Method 3

forming ejection port members with a material different from that of its substrate causes stress due to a difference in the coefficient of thermal expansion

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS10479084B2Method for manufacturing liquid ejection head

Publication Date: 2019.11.19 CANON KK

AI summary

A method for manufacturing liquid ejection heads includes the steps of forming ejection port members on a substrate, the ejection port members each having a liquid channel and an ejection port for ejecting liquid through the channel, the liquid channel communicating with the substrate; forming supply ports passing through the substrate to supply liquid to the channels; and forming a separation groove in the substrate to separate the substrate for each liquid ejection head. The step of forming the ejection port members includes the step of hardening a material constituting the ejection port member by heat treatment. The step of forming the separation groove is performed before the step of hardening.