LED Chip Raised Border Phosphor Resin Retention

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Solution Overview

Problem

Current light emitting diode (LED) structures, particularly those using the mini-glob technique, suffer from high variation in color output and blue light leakage due to the difficulty in positioning large phosphor particles, leading to inefficient white light emission and increased fabrication costs.

Innovation Solution

A light emitting diode structure featuring a raised border around the perimeter of the top surface, filled with a polymer resin containing phosphor particles, which allows for a thicker resin edge and better retention of phosphor particles, minimizing blue light leakage and enhancing color uniformity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If large phosphor particles are used in the mini-glob technique, then white light conversion efficiency is improved, but positioning precision deteriorates and blue light leakage increases

Engineering Contradiction:
Improvewhite light conversion efficiencyVSAvoidphosphor particle positioning precision
Core Design Contradiction:
Loss of energyVSManufacturing precision

Solution Approach 1:

The invention divides the phosphor-containing resin into multiple discrete globules, each containing phosphor particles of appropriate size for efficient light conversion. This segmentation allows large phosphor particles to be contained within individual globules rather than requiring precise positioning across the entire LED surface, thus maintaining conversion efficiency while reducing positioning complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention transitions from a two-dimensional planar phosphor layer to a three-dimensional array of resin globules with varying sizes and positions. This dimensional change allows phosphor particles to be distributed volumetrically within each globule, improving light conversion while the globule structure itself provides the positioning function, eliminating the need for precise lateral positioning of individual particles.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Illumination intensity

If large phosphor particles are used, then yellow light emission is enhanced, but blue light leakage increases due to poor retention

Engineering Contradiction:
Improveyellow light emission intensityVSAvoidblue light leakage
Core Design Contradiction:
Illumination intensityVSObject-generated harmful factors

Solution Approach 1:

The invention nests phosphor particles within encapsulating resin globules, creating a hierarchical structure where particles are contained within a matrix that provides both structural support and optical confinement. This nesting ensures that large phosphor particles remain retained within the resin globules, converting blue light to yellow light efficiently without allowing blue light to leak through gaps between particles.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The invention uses composite resin globules containing phosphor particles dispersed within the resin matrix. This composite structure combines the light-converting properties of large phosphor particles with the retaining and optically homogeneous properties of the resin, achieving both strong yellow light emission and effective prevention of blue light leakage simultaneously.

Inventive Principle:
Principle #40Composite materials

3Object-generated harmful factors

If the resin layer is made thicker to retain phosphor particles, then blue light leakage is reduced, but fabrication complexity increases

Engineering Contradiction:
Improveblue light leakageVSAvoidfabrication complexity
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The invention employs self-assembled resin globules that form through controlled drying or curing processes, where the globule size and distribution emerge dynamically during fabrication rather than requiring precise pre-positioning. This dynamic formation process simplifies fabrication by allowing the structure to self-organize into the desired configuration with appropriate thickness for retaining phosphor particles and preventing blue light leakage.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The resin globules serve multiple functions simultaneously: they contain and retain the phosphor particles, provide the necessary thickness to prevent blue light leakage, and maintain optical homogeneity. This multi-functionality reduces fabrication complexity by eliminating the need for separate structures or processes to address each of these requirements independently.

Inventive Principle:
Principle #25Self-service

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 solution achieves improved color uniformity and reduced blue light leakage, resulting in a more efficient conversion of blue light to yellow, thereby producing a consistent white output with reduced fabrication complexity and costs.

Implementation Method 1

phosphor particles in the resin that convert the frequencies emitted by the active portion

Methodology Applied
Scientific EffectPhotoluminescence: Photoluminescence

Data Source

PatentEP2015374B1LED chip design for white conversion
Publication Date: 2018.03.21 WOLFSPEED INC
  • EP2015374B1 patent drawingFigure 1~3
  • EP2015374B1 patent drawingFigure 4~6
  • EP2015374B1 patent drawingFigure 7

AI summary

A method of tuning a light-emitting diode (27) is provided, comprising the steps of: measuring the wavelength and/or radiant flux produced by the light-emitting diode, and thereafter covering the diode with an amount of phosphor (34) combined with a polymer resin (33) that produces a selected colour based upon the measured colour and the added phosphor in the resin.