Laser Processing Light-Emitting Diode Gallium Layer Removal

Solution Overview

Problem

Current methods for removing the gallium layer from light-emitting diodes, such as pickling with hydrogen chloride, damage substrates and solder/bump materials, reduce yield, and cause environmental pollution, while also limiting light extraction efficiency.

Innovation Solution

Applying an energy beam with a power density between 0 and 2000 mJ/cm2 to separate the light-emitting diode from its substrate and form a surface-roughened layer, effectively removing the gallium residue and improving light extraction efficiency without chemical damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If pickling with hydrogen chloride is used to remove the gallium layer, then the gallium layer is removed, but the substrate and solder/bump material are damaged, yield decreases, and environmental pollution occurs

Engineering Contradiction:

Improvegallium layer removalVSAvoidsubstrate and solder/bump material damage

Core Design Contradiction:

Loss of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the chemical pickling process with a physical laser processing method. The laser beam directly ablates the gallium layer through controlled heating and vaporization, eliminating the need for chemical reagents like hydrogen chloride. This substitution of chemical mechanism with physical mechanism resolves the contradiction by achieving gallium removal without chemical damage to substrates and solder materials.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent utilizes controlled changes in laser processing parameters (power density, pulse duration, wavelength) to selectively remove the gallium layer while preserving the underlying substrate and solder/bump materials. By precisely adjusting these parameters, the process achieves selective ablation based on the different thermal properties and absorption characteristics of the various materials involved, thus removing gallium without causing damage.

Inventive Principle:

Principle #35Parameter changes

2Loss of substance

If pickling with hydrogen chloride is used to remove the gallium layer, then the gallium layer is removed, but environmental pollution occurs

Engineering Contradiction:

Improvegallium layer removalVSAvoidenvironmental pollution

Core Design Contradiction:

Loss of substanceVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the chemical pickling process with a physical laser processing method. The laser beam directly ablates the gallium layer through controlled heating and vaporization, eliminating the need for chemical reagents like hydrogen chloride. This substitution of chemical mechanism with physical mechanism resolves the contradiction by achieving gallium removal without chemical damage to substrates and solder materials.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent converts the potentially harmful gallium residue into a removable byproduct through laser ablation. The gallium layer, which would otherwise remain as a contaminant affecting light emission, is completely vaporized and removed by the laser energy. This transformation turns the harmful residue into a controlled removal process with no harmful chemical waste generation.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Loss of substance

If pickling with hydrogen chloride is used to remove the gallium layer, then the gallium layer is removed, but light extraction efficiency is not improved

Engineering Contradiction:

Improvegallium layer removalVSAvoidlight extraction efficiency

Core Design Contradiction:

Loss of substanceVSIllumination intensity

Solution Approach 1:

The patent utilizes controlled changes in laser processing parameters (power density, pulse duration, wavelength) to selectively remove the gallium layer while preserving the underlying substrate and solder/bump materials. By precisely adjusting these parameters, the process achieves selective ablation based on the different thermal properties and absorption characteristics of the various materials involved, thus removing gallium without causing damage.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a concave curvature or depression on the LED chip surface through controlled laser ablation. This curved surface structure improves light extraction efficiency by reducing total internal reflection and enhancing light emission in multiple directions. The curvature modification, achieved through precise laser processing, directly addresses the light extraction efficiency issue that simple planar gallium removal cannot resolve.

Inventive Principle:

Principle #14Spheroidality (Curvature)

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 enhances light extraction efficiency while being environmentally friendly, avoiding the drawbacks of chemical pickling and maintaining material integrity, thus aligning with green production trends.

Implementation Method 1

An energy beam is applied to process a surface of the light-emitting diode, where a power density of the energy beam is greater than 0 mJ/cm2 and less than or equal to 2000 mJ/cm2

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Implementation Method 2

An undoped gallium nitride layer is usually decomposed into a gallium layer and a nitrogen layer by using laser, to separate the light-emitting diode from a sapphire substrate

Methodology Applied

Scientific EffectLaser decomposition: Laser Ablation

Data Source

PatentUS11239389B2Method for manufacturing light-emitting element and electronic device applying light-emitting element

Publication Date: 2022.02.01 INNOLUX CORP

AI summary

The disclosure provides a method for manufacturing a light-emitting element, including the following steps. A light-emitting diode is provided. An energy beam is applied to process a surface of the light-emitting diode, where a power density of the energy beam is greater than 0 mJ/cm2 and less than or equal to 2000 mJ/cm2. The light-emitting element manufactured using the method for manufacturing a light-emitting element disclosed in embodiments of the disclosure may improve light extraction efficiency, may have a relatively good light-emitting effect, and may be electrically connected to a drive circuit to constitute an electronic device.