Perforated Substrate Etching via Resin Hole Sealing

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Solution Overview

Problem

Existing methods for manufacturing liquid ejection heads face challenges in efficiently removing protective film layers from heater elements, leading to increased energy loss and reduced thermal efficiency, while also causing unintended etching of non-standardized through holes, which can adversely affect production yield.

Innovation Solution

A perforated substrate processing method where a resin material is used to close through holes during the etching process, preventing etching solution or gas from reaching non-standardized holes and reducing the impact of misaligned or oversized holes on adjacent ones, thereby improving production yield.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If photoresist is used to cover through holes as etching mask, then the protective film layer can be selectively removed from heater elements, but non-standardized through holes may not be completely covered leading to unintended etching

Engineering Contradiction:

Improveselective removal of protective filmVSAvoidcoverage of through holes by etching mask

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The resin material is applied to fill the through holes before the etching process begins. This preliminary action ensures that even non-standardized through holes are completely sealed, preventing any etching solution or gas from reaching the substrate through misplaced or oversized holes during the subsequent etching step.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The resin material acts as an intermediary substance that temporarily fills the through holes during the etching process. This intermediary material provides a physical barrier that prevents the etching solution or gas from penetrating through the through holes to the rear surface of the substrate, while allowing the etching to proceed normally on the front surface.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If through holes are not completely covered by etching mask, then etching solution or gas can reach rear surface of substrate, but this causes adverse effects on remaining through holes and chips

Engineering Contradiction:

Improveproduction yield of wafersVSAvoidunintended etching of through holes

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The resin material serves as a cushioning barrier that is placed beforehand in the through holes to prevent any harmful etching solution or gas from reaching the rear surface of the substrate. This prior protective measure ensures that even if misalignment or sizing issues occur with the photoresist mask, the substrate remains protected from unintended etching.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If protective film layer remains on heater elements, then through holes are protected, but thermal efficiency of heater elements decreases

Engineering Contradiction:

Improveprotective coverage of through holesVSAvoidthermal efficiency of heater elements

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The etching process is applied locally and selectively only to the heater elements where the protective film needs to be removed for thermal efficiency, while the through holes remain protected by the resin material. This localized approach allows differential treatment: the heater elements receive etching to improve thermal contact, while the through holes are shielded to maintain their protective film coverage.

Inventive Principle:

Principle #3Local quality

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 method effectively suppresses the adverse effects of non-standardized through holes on the etching process, enhancing the thermal efficiency of heater elements and significantly improving the production yield of wafers by preventing unwanted etching and energy loss.

Implementation Method 1

a closing step of allowing part of the resin material to drop into each of the plurality of through holes

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Implementation Method 2

a step of etching the exposed etching object under a condition where each of the through holes is closed at least partly with the resin material

Methodology Applied

Scientific EffectChemical etching:

Data Source

PatentUS10632754B2Perforated substrate processing method and liquid ejection head manufacturing method

Publication Date: 2020.04.28 CANON KK

AI summary

A perforated substrate having a first surface, a second (opposite) surface, a plurality of through holes running through the substrate from the first surface to the second surface and an etching object arranged on the first surface, is processed by forming a coating layer containing a resin material on the etching object, then allowing part of the resin material to drop into each of the through holes so as to close each of the through holes at least partly with the dropped resin material, then patterning the coating layer such that the coating layer is left on each of the through holes as mask while at least part of the coating layer covering the etching object is removed to expose the etching object; and etching the exposed etching object under a condition where each of the through holes is closed at least partly with the resin material.