UV Absorbing Layer and Soft Resin for LED Stability

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Solution Overview

Problem

Semiconductor light emitting devices with white LEDs face challenges due to the degradation of sealing resins caused by ultraviolet light, particularly affecting AlInGaP based LED chips with lower hardness, which are not adequately protected by conventional ultraviolet absorbing resins.

Innovation Solution

The implementation of a semiconductor light emitting device structure that includes a GaN based blue LED chip and an AlInGaP based yellow LED chip, both covered with an ultraviolet absorbing layer and sealed using a resin with lower hardness than the absorbing layer, reducing the stress on the AlInGaP chip and minimizing ultraviolet light exposure to the sealing resin.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an ultraviolet absorbing resin is used to seal the LED chips, then the sealing resin is protected from ultraviolet light degradation, but the AlInGaP based LED chip is damaged by stress from the hard resin

Engineering Contradiction:

Improvesealing resin stabilityVSAvoidLED chip integrity

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent changes the hardness parameter of the sealing resin by selecting a resin with lower hardness than the ultraviolet absorbing layer. This parameter change allows the resin to be soft enough not to damage the AlInGaP LED chip while still providing effective ultraviolet light absorption protection, thus resolving the contradiction between resin stability and chip integrity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite structure consisting of an ultraviolet absorbing layer with high hardness and a sealing resin with lower hardness. This composite material approach allows the ultraviolet absorbing layer to provide both ultraviolet protection and mechanical support, while the softer sealing resin provides sealing without damaging the LED chip

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If a hard ultraviolet absorbing resin is used, then ultraviolet light protection is effective, but stress from the resin damages the AlInGaP based LED chip

Engineering Contradiction:

Improveultraviolet light protectionVSAvoidLED chip damage

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The patent applies local quality by creating distinct layers with different properties: the ultraviolet absorbing layer has high hardness for effective ultraviolet protection, while the sealing resin has lower hardness to avoid damaging the LED chip. Each layer performs its specific function optimally without compromising the other

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The ultraviolet absorbing layer acts as an intermediary between the ultraviolet light source and the sealing resin. It absorbs the harmful ultraviolet light and provides a protective barrier, allowing the sealing resin to be softer and less likely to damage the LED chip while still providing adequate ultraviolet protection

Inventive Principle:

Principle #24Intermediary (Mediator)

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 enhances the long-term stability and life of the semiconductor light emitting device by reducing resin degradation and minimizing damage to the AlInGaP LED chip, while maintaining efficient light emission and color fraction of white light.

Implementation Method 1

an ultraviolet absorbing layer configured to cover the light extraction surface of the first semiconductor light emitting element

Methodology Applied

Scientific EffectUltraviolet absorption: Absorption (EM radiation)

Data Source

PatentUS8164102B2Semiconductor light emitting device

Publication Date: 2012.04.24 SEOUL SEMICONDUCTOR

AI summary

A semiconductor light emitting device may include a first lead; a second lead; a first semiconductor light emitting element mounted on the first lead, being configured to emit a light having an optical emission spectrum no more than 400 nm from a light extraction surface of the first semiconductor light emitting element; a second semiconductor light emitting element mounted on the second lead, being configured to emit a light having a peak wavelength in no less than 550 nm; an ultraviolet absorbing layer configured to cover the light extraction surface of the first semiconductor light emitting element; and a sealing resin configured to cover the ultraviolet absorbing layer, first semiconductor light emitting element and the second semiconductor light emitting element.