Flexible Light Emitting Device Stress Management

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Light emitting devices with flexible substrates experience stress issues when adhesive layers or magnet tapes are applied to the back surface, leading to potential deterioration and detachment of the light emitting elements during installation on mounting substrates.

Innovation Solution

A light emitting device design featuring a flexible substrate with a cover member, reflective member, and light transmissive member, where the adhesive layer is strategically applied with through holes or reduced thickness to minimize stress on the light emitting elements, allowing for flexible installation without direct fixation to the substrate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If adhesive layer is disposed on the whole surface of the back surface side of the substrate, then the light emitting device can be securely installed on mounting substrate, but stress is applied to the light emitting element which may cause deterioration and detachment

Engineering Contradiction:

Improveinstallation securityVSAvoidstress on light emitting element

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The adhesive layer is configured with non-uniform thickness, being thicker at the peripheral portion and thinner at the central portion of the back surface. This local quality variation allows the peripheral adhesive to provide strong bonding for secure installation, while the reduced central thickness minimizes stress transmission to the light emitting element positioned at the center, thereby resolving the contradiction between installation security and element protection

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The adhesive layer is segmented into different thickness regions - a first adhesive layer at the peripheral portion and a second adhesive layer at the central portion with different thickness characteristics. This segmentation allows each region to perform its specific function: the peripheral region provides anchoring strength while the central region reduces stress on the light emitting element

Inventive Principle:

Principle #1Segmentation

2Reliability

If adhesive layer is disposed on the whole surface of the back surface side, then the light emitting element is fixed to the mounting substrate, but this fixation causes stress and potential detachment of the light emitting element from the flexible substrate

Engineering Contradiction:

Improvedevice stabilityVSAvoidbonding strength between light emitting element and flexible substrate

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

By making the adhesive layer thinner at the central portion where the light emitting element is located, the bonding strength in that specific region is reduced, preventing excessive stress from detaching the element from the flexible substrate. Meanwhile, the thicker peripheral adhesive maintains overall device stability and secure mounting

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 design minimizes stress on the light emitting elements, preventing deterioration and detachment, while maintaining flexibility and enabling secure bonding to various substrates, thus enhancing the reliability and durability of the light emitting device.

Implementation Method 1

The reflective member covers at least a part of a lower surface and at least a part of a side surface of the at least one light emitting element

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

The light transmissive member covers a top surface of the at least one light emitting element

Methodology Applied

Scientific EffectLight transmission:

Data Source

PatentUS11276802B2Light emitting device

Publication Date: 2022.03.15 NICHIA CORP

AI summary

A light emitting device includes a flexible substrate, at least one light emitting element, a cover member, a reflective member and a light transmissive member. The flexible substrate has a first surface and a second surface opposite to the first surface, and includes a flexible base member and a plurality of wiring portions disposed on a first surface side. The light emitting element is arranged on the first surface of the flexible substrate and electrically connected to the wiring portions. The cover member is arranged on the second surface of the flexible substrate and defines a through hole at a position overlapping the light emitting element in a plan view. The reflective member covers at least a part of a lower surface and at least a part of a side surface of the light emitting element. The light transmissive member covers a top surface of the light emitting element.