Composite Phosphor Coating for Stable Red-Emitting LED Packages

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Solution Overview

Problem

Manganese (Mn4+) doped fluoride phosphors used in LED lighting systems are susceptible to degradation under use conditions, limiting their stability and longevity.

Innovation Solution

A process for fabricating LED lighting apparatus involving a composite coating with a first layer of manganese doped phosphor and a second layer of another phosphor composition, both mixed with poly(meth)acrylate binders, applied at the melting temperature of the binder to enhance stability and performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If manganese doped fluoride phosphors are used in LED lighting systems, then high quantum efficiency and luminous efficacy are achieved, but the phosphors are susceptible to degradation under use conditions

Engineering Contradiction:

Improvequantum efficiencyVSAvoidstability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies composite materials by combining manganese doped fluoride phosphor particles with a polymer binder to form a composite phosphor material. This composite structure protects the phosphor particles from degradation while maintaining their high quantum efficiency, resolving the contradiction between performance and stability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the physical state of the phosphor by incorporating it into a polymer matrix, transforming it from a loose powder to a stabilized composite material. This parameter change in the material's physical state protects against degradation while preserving optical properties.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If a surface coating of doped phosphor dispersed in a binder is applied, then the manufacturing process is simplified, but the stability and performance of the LED lighting system are compromised

Engineering Contradiction:

Improvemanufacturing processVSAvoidstability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent creates a composite phosphor-binder material where the phosphor is dispersed within a polymer matrix. This composite structure maintains ease of application as a surface coating while significantly improving stability and performance compared to simple phosphor-binder mixtures.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies the composite phosphor material as a surface coating on the LED chip, providing localized protection and performance enhancement exactly where the phosphor is needed, while maintaining the simplicity of a coating application process.

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

The approach improves the stability and performance of the LED lighting systems by maximizing quantum efficiency and luminous efficacy while maintaining high color rendering index (CRI) and color temperature, reducing degradation issues.

Implementation Method 1

Red-emitting phosphors based on complex fluoride materials activated by Mn 4+ from a blue LED... These materials absorb blue light strongly and efficiently emit between about 610-635 nm... Quantum efficiency can exceed 85% under blue (440-460 nm) excitation.

Methodology Applied

Scientific EffectPhotoluminescence: Photoluminescence

Implementation Method 2

Methodology Applied

Scientific EffectMelting: Melting

Data Source

PatentEP3155669B1Method for fabricating a LED package with red-emitting phosphors

Publication Date: 2024.03.27 GE LIGHTING SOLUTIONS LLC

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AI summary

A process for fabricating a LED lighting apparatus includes disposing a composite coating on a surafce of a LED chip, The composite coating comprises a first composite layer having a manganese doped phosphor of formula I and a first binder and a second composite layer comprising a second phosphor composition and a second binder. The first binder, the second binder or both include a poIy(meth)acrylate. Ax [MFy]:Mn4+.......... (I), wherein A is Li, Na. K, Rb, Cs, or a combination thereof; M is Si, Ge, Sn, Ti, Zr, AL Ga, In, Sc, Hf, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; x is the absolute value of the charge of the [MFy] ion; y is 5, 6 or 7.