Light Emitting Device Wiring Structure for Enhanced Light Extraction

Solution Overview

Problem

The light extraction efficiency of light emitting devices is reduced due to light absorption by the substrate surface, particularly when the reflective member's material and thickness are not optimally designed between light emitting elements and the mounting board.

Innovation Solution

A light emitting device with a mounting board featuring wiring structures where first wiring parts with higher reflectance than bonding members are used to efficiently reflect light, and second wiring parts made of the same material as the bonding members for improved bonding strength, along with a reflective member covering the bonding members and wiring structures to enhance light extraction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a reflective member is disposed between light emitting elements and the mounting board, then light extraction efficiency is improved, but light can still reach and be absorbed by the substrate surface when the reflective member's material and thickness are not optimally designed

Engineering Contradiction:

Improvelight extraction efficiencyVSAvoidlight absorption by substrate

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The wiring structure is divided into two distinct parts: a first wiring part with high reflectance for reflecting light, and a second wiring part made of the same material as bonding members for bonding light emitting elements. This segmentation allows each part to perform its specific function optimally without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different parts of the wiring structure are assigned different properties: the first wiring part has high reflectance to reflect light back into the device, while the second wiring part has bonding compatibility with the light emitting elements. This local differentiation of properties resolves the contradiction between light reflection and substrate absorption.

Inventive Principle:

Principle #3Local quality

2Loss of energy

If the first wiring parts have higher reflectance than bonding members, then light reflection is improved, but bonding strength between elements and mounting board may be compromised

Engineering Contradiction:

Improvelight reflection efficiencyVSAvoidbonding strength

Core Design Contradiction:

Loss of energyVSStrength

Solution Approach 1:

The wiring structure is divided into two distinct parts: a first wiring part with high reflectance for reflecting light, and a second wiring part made of the same material as bonding members for bonding light emitting elements. This segmentation allows each part to perform its specific function optimally without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different parts of the wiring structure are assigned different properties: the first wiring part has high reflectance to reflect light back into the device, while the second wiring part has bonding compatibility with the light emitting elements. This local differentiation of properties resolves the contradiction between light reflection and substrate absorption.

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 increases light extraction efficiency by reflecting light emitted from the elements back into the device, reducing absorption by the substrate and improving bonding strength between elements and the mounting board.

Implementation Method 1

A reflectance of the one or more first wiring parts is higher than a reflectance of the bonding members

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS10367129B2Light emitting device

Publication Date: 2019.07.30 NICHIA CORP

AI summary

A light emitting device includes a mounting board including: a base part, and one or more wiring structures, each of which includes one or more first wiring parts, and one or more second wiring parts, in that order, from a base part side, wherein, in a plan view, an area of each of the one or more second wiring parts is smaller than an area of each of the one or more first wiring parts; one or more light emitting elements bonded to the second wiring parts via bonding members; and a reflective member covering at least a portion of the bonding members and at least a portion of the one or more wiring structures. A reflectance of the one or more first wiring parts is higher than a reflectance of the bonding members. The one or more second wiring parts and the bonding members comprise the same material at their outermost surfaces.