Wavelength Converting Layer for LED Packaging

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Solution Overview

Problem

Current light emitting devices with wavelength converting layers face challenges in simplifying the mounting and wire bonding processes for multiple LED chips, leading to increased package size and potential light loss, as well as damage to the wavelength converting layer from emitted light.

Innovation Solution

A light emitting device with a wavelength converting layer covering multiple semiconductor stacked structures, where additional electrodes are only disposed at current input and output terminals, allowing for simplified wire bonding and integration, and a spacer layer with a distributed Bragg reflector is used to prevent light from being re-absorbed by the LED chip, enhancing light efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple LED chips are individually mounted with wire bonding at package level, then electrical connection is achieved, but the packaging process becomes complex and package size increases

Engineering Contradiction:
Improveelectrical connectionVSAvoidpackaging process
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

Multiple LED chips are electrically connected to each other by conductive adhesive directly on the substrate, merging the electrical connection function into the mounting process itself, thereby eliminating the need for separate wire bonding steps and simplifying the overall packaging process

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

Electrical connections between LED chips are established during the mounting process using conductive adhesive before final packaging, performing the electrical connection action in advance rather than as a separate subsequent step

Inventive Principle:
Principle #10Preliminary action

2Reliability

If multiple LED chips are individually mounted, then electrical connection is achieved, but the package size increases making it difficult to provide a point light source

Engineering Contradiction:
Improveelectrical connectionVSAvoidpackage size
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The electrical connection function is merged into the mounting process by using conductive adhesive, allowing multiple LED chips to be connected directly to the substrate without additional wire bonding components, thereby reducing the overall package volume

Inventive Principle:
Principle #5Merging (Combining)

3Ease of manufacture

If wavelength converting layer is applied at wafer level, then manufacturing process is simplified, but light damage to the wavelength converting layer occurs

Engineering Contradiction:
Improvemanufacturing processVSAvoidlight damage
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The wavelength converting layer is applied to individual LED chips after they are mounted on the substrate, performing the coating action after the chips are in their final positions, thereby preventing light damage that would occur if coating were done at the wafer level before mounting

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

This solution simplifies the packaging process, reduces the size of the light source, and improves light efficiency by preventing light conversion loss and protecting the wavelength converting layer from damage.

Implementation Method 1

a wavelength converting layer for covering the plurality of semiconductor stacked structures

Methodology Applied
Scientific EffectPhotoluminescence: Photoluminescence

Implementation Method 2

a spacer layer with a distributed Bragg reflector is used to prevent light from being re-absorbed by the LED chip

Methodology Applied
Scientific EffectBragg reflection: Bragg Diffraction

Data Source

PatentEP2673812B1Light emitting device having wavelength converting layer
Publication Date: 2020.12.02 SEOUL SEMICONDUCTOR
  • EP2673812B1 patent drawingFigure 1~4
  • EP2673812B1 patent drawingFigure 5~7
  • EP2673812B1 patent drawingFigure 8~10

AI summary

Disclosed is a light emitting device having a wavelength converting layer. The light emitting device comprises a plurality of semiconductor stacked structures; connectors for electrically connecting the plurality of semiconductor stacked structures to one another; a single wavelength converting layer for covering the plurality of semiconductor stacked structures; an electrode electrically connected to at least one of the semiconductor stacked structures; and at least one additional electrode positioned on the electrode, passing through the wavelength converting layer to be exposed to the outside, and forming a current input terminal to the light emitting device or a current output terminal from the light emitting device. Since the single wavelength converting layer covers the plurality of semiconductor stacked structures, the plurality of semiconductor stacked structures can be integrally mounted on a chip mounting member such as a package or a module.