LED Light Extraction via Segmented Reflective and Gold-Plated Bonding Regions

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Solution Overview

Problem

Existing LED light emitting apparatuses face challenges in increasing light extraction efficiency while maintaining reliable connections to LED devices, due to issues with reflectivity and surface treatment in the device mounting region and wire connecting regions.

Innovation Solution

The solution involves forming a reflective layer in the device mounting region and using a gold-plated layer for the opposing electrodes to enhance connection reliability, with a sealing frame that covers the reflective layer to minimize light loss, and using a metal plate with a high-reflectivity insulating layer for improved heat dissipation and light extraction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a reflective layer is formed in the device mounting region to increase light extraction efficiency, then light extraction efficiency is improved, but the reliability of wire connections deteriorates due to poor bondability of reflective materials

Engineering Contradiction:
Improvelight extraction efficiencyVSAvoidconnection reliability
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

The mounting substrate surface is divided into two distinct regions: a device mounting region with a reflective layer for high light extraction efficiency, and a wire connecting region with a gold-plated layer for reliable wire bondability. This segmentation allows each region to have optimized properties for its specific function without compromise.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different surface treatments are applied to different locations on the mounting substrate: the device mounting region receives a reflective layer (silver or aluminum) to maximize light extraction, while the wire connecting region receives a gold-plated layer to ensure excellent wire bondability. This local differentiation resolves the contradiction by providing locally optimized properties.

Inventive Principle:
Principle #3Local quality

2Loss of energy

If the entire mounting substrate surface is treated for high reflectivity to maximize light extraction, then light extraction efficiency is improved, but wire bondability deteriorates

Engineering Contradiction:
Improvelight extraction efficiencyVSAvoidwire bondability
Core Design Contradiction:
Loss of energyVSEase of manufacture

Solution Approach 1:

The mounting substrate surface is segmented into functional zones: the device mounting region is covered with a reflective layer for optimal light extraction, while the wire connecting region is covered with a gold-plated layer for optimal wire bonding. This avoids applying reflective materials to areas where they would harm wire bondability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The surface treatment is made location-specific: high reflectivity is provided only where needed for light extraction (device mounting region), while gold plating is provided where needed for connection reliability (wire connecting region). This local quality approach maximizes light extraction without sacrificing wire bondability.

Inventive Principle:
Principle #3Local quality

3Loss of energy

If reflective materials like silver or aluminum are used for the entire surface to improve light extraction, then light extraction efficiency is improved, but connection reliability worsens due to poor bonding characteristics

Engineering Contradiction:
Improvelight extraction efficiencyVSAvoidconnection reliability
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

The surface is segmented into two functional areas with different materials: silver or aluminum reflective layer in the device mounting region for high light extraction efficiency, and gold-plated layer in the wire connecting region for reliable wire connections. This material segmentation resolves the contradiction between light extraction and connection reliability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different materials are applied locally according to functional requirements: reflective materials (silver/aluminum) are applied only in the device mounting region where light extraction is critical, while gold plating is applied in the wire connecting region where bondability is critical. This local material selection optimizes both light extraction and connection reliability.

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

This configuration significantly increases light extraction efficiency and enhances the reliability of connections to the LED devices, while also improving heat dissipation performance.

Implementation Method 1

forming a reflective layer in the device mounting region

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

the opposing electrodes are plated with gold to improve the wire bondability of the LED devices

Methodology Applied
Scientific EffectElectroplating: Electroplating

Implementation Method 3

a sealing frame that covers the reflective layer to minimize light loss

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 4

using a metal plate with a high-reflectivity insulating layer for improved heat dissipation and light extraction

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP2835837B1Light emitting device with light emitting diodes
Publication Date: 2019.08.07 CITIZEN WATCH CO LTD
  • EP2835837B1 patent drawingFigure 1
  • EP2835837B1 patent drawingFigure 2~3
  • EP2835837B1 patent drawingFigure 4

AI summary

The purpose of the present invention is to provide an LED light emitting apparatus, which has both the high reliability with respect to connection of the LED elements, and improved light extraction efficiency. This LED light emitting apparatus is characterized in having: a mounting substrate having an element mounting region, in which a reflection layer is formed; a plurality of LED elements mounted in the element mounting region; a pair of facing electrodes, which have gold plating layers formed thereon, respectively, which are provided around the element mounting region, and which are connected to the LED elements by wire bonding; and a sealing frame, which is disposed around the element mounting region so as to cover the pair of facing electrodes. The LED light emitting apparatus is also characterized in that the inner circumference of the sealing frame is provided at a position where the inner circumference of the sealing frame covers the outer circumference of the reflection layer.