Wavelength Conversion Element Polishing for Air-Bubble-Free Joining

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Solution Overview

Problem

Existing wavelength conversion elements face issues with air bubbles being trapped inside due to level differences formed during the manufacturing process, leading to appearance failures and potential defects from thermal expansion or contraction.

Innovation Solution

A method involving forming a periodic polarization inversion structure on a ferroelectric substrate, followed by etching to create level differences, applying a joining layer, and then polishing the surface to ensure a smooth join with a support substrate, thereby preventing air bubbles from being enclosed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a joining layer is formed on the substrate with periodic polarization inversion structure to join to support substrate, then joining is achieved, but level differences from etching cause gaps and air bubbles to be enclosed

Engineering Contradiction:

Improvejoining qualityVSAvoidair bubbles enclosed

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by performing polishing on the joining layer before the actual joining process. This preliminary surface treatment removes the level differences created by etching, ensuring a flat surface that prevents gap formation and air bubble enclosure during subsequent joining operations with the support substrate.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If etching is performed to form level differences for confirming periodic polarization inversion structure, then formation accuracy is verified, but gaps are formed between joining layer and support substrate

Engineering Contradiction:

Improveformation accuracy confirmationVSAvoidsurface flatness

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The polishing step is performed as a preliminary action after etching but before joining. This removes the level differences that were temporarily created for verification purposes, restoring surface flatness while preserving the underlying periodic polarization inversion structure, thus eliminating gaps in the final joined product.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent extracts or removes the harmful level differences from the joining layer surface through polishing, while retaining the essential periodic polarization inversion structure underneath. This separation allows the verification function to be temporarily utilized without compromising the final manufacturing precision.

Inventive Principle:

Principle #2Taking out (Extraction)

3Ease of manufacture

If joining layer is formed directly on etched substrate, then manufacturing process is simplified, but air bubbles are enclosed causing appearance failures

Engineering Contradiction:

Improveprocess simplicityVSAvoidappearance quality

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent introduces a preliminary polishing step between joining layer formation and the joining process. While this adds one more step to the manufacturing process, it is a simple surface treatment that effectively prevents air bubble enclosure and appearance failures, thereby improving overall product reliability.

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 method effectively prevents air bubbles from being trapped within the wavelength conversion element, ensuring a smooth surface for reliable operation and avoiding defects such as appearance failures and joining issues.

Implementation Method 1

etching a surface of the ferroelectric substrate provided with the periodic polarization inversion structure, to form level differences between the polarization inversion portions and the non-polarization inversion portions

Methodology Applied

Scientific EffectEtching:

Implementation Method 2

polishing a surface of the joining layer to cause the joining layer to have a second thickness

Methodology Applied

Scientific EffectPolishing:

Data Source

PatentUS20250306429A1Method of manufacturing wavelength conversion element, and wavelength conversion element

Publication Date: 2025.10.02 NGK INSULATORS LTD

AI summary

A method of manufacturing a wavelength conversion element including a periodic polarization inversion structure, includes: forming the periodic polarization inversion structure by alternately forming polarization inversion portions and non-polarization inversion portions on a ferroelectric substrate; etching a surface of the ferroelectric substrate provided with the periodic polarization inversion structure, to form level differences between the polarization inversion portions and the non-polarization inversion portions; forming a joining layer having a first thickness on the ferroelectric substrate provided with the level differences; polishing a surface of the joining layer to cause the joining layer to have a second thickness; and joining a support substrate to the polished surface of the joining layer.