LED Lighting Device Thermal Management via Composite Encapsulation

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Solution Overview

Problem

Lighting devices with medium to high power LED sources face challenges in heat dissipation due to low thermal conductivity of encapsulation materials, leading to complex and expensive solutions that compromise device geometry and appearance.

Innovation Solution

Incorporating a thermally-conductive material within the encapsulation, such as a silicone or polyurethane matrix with dispersed particles, that is strategically positioned to enhance heat dissipation without altering the device's structure or visibility, allowing for flexible design and use of standard materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If encapsulation materials with low thermal conductivity are used to achieve protection against penetration of foreign agents, then protection against foreign agents is improved, but heat dissipation deteriorates

Engineering Contradiction:

Improveprotection against penetration of foreign agentsVSAvoidheat dissipation

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent employs a composite encapsulation structure consisting of an outer protective layer made of low thermal conductivity material (for IP protection) and an inner heat dissipation layer made of high thermal conductivity material (for heat removal). This composite approach allows simultaneous achievement of both protection and thermal management functions.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The encapsulation is divided into functionally distinct segments: an outer protective encapsulation layer and an inner heat dissipation layer. Each layer performs its specific function independently, with the protective layer providing foreign agent resistance and the heat dissipation layer providing thermal conduction pathways.

Inventive Principle:

Principle #1Segmentation

2Temperature

If thermally-conductive layers made of copper with specific structure are provided on device substrate to improve heat dissipation, then heat dissipation is improved, but device complexity and cost increase

Engineering Contradiction:

Improveheat dissipationVSAvoiddevice implementation complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The heat dissipation function is extracted from the substrate and relocated to the encapsulation structure. Instead of modifying the substrate with complex copper layers, the patent places thermally-conductive material within the encapsulation layers, simplifying substrate design while achieving effective heat removal.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The encapsulation structure acts as an intermediary between the light radiation sources and the external environment, providing both protective and thermal management functions. The thermally-conductive layer within the encapsulation serves as a mediator that conducts heat away from the sources without requiring direct substrate modification.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Temperature

If thermally-conductive material is incorporated within encapsulation to enhance heat dissipation, then heat dissipation is improved, but device geometry may be affected

Engineering Contradiction:

Improveheat dissipationVSAvoiddevice geometry

Core Design Contradiction:

TemperatureVSShape

Solution Approach 1:

The thermally-conductive material is strategically positioned in specific locations within the encapsulation structure where heat dissipation is most needed, rather than uniformly distributing it throughout. This localized approach enhances thermal performance while minimizing impact on overall device geometry and appearance.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The thermally-conductive layer is nested within the protective encapsulation layer, with the heat dissipation structure contained inside the protective outer shell. This nested arrangement allows the heat dissipation elements to be hidden from external view, preserving device appearance while providing effective thermal management.

Inventive Principle:

Principle #7Nested doll (Nesting)

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 effectively increases light output power while improving heat dissipation without affecting the device's geometry or appearance, allowing for adaptable heat management tailored to the application and usage needs, using readily available materials and simplifying production and handling.

Implementation Method 1

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP3351852B1A lighting device and corresponding manufacturing method

Publication Date: 2019.10.30 OSRAM SOC RIUNITE OSRAM EDISON CLERICI

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Figure 4a~4e
Figure 5a~5e

AI summary

A lighting device (10) includes: - an elongated laminar substrate (12) having opposed front and back surfaces, - one or more electrically-powered light radiation sources (14), e.g. LED sources, at the front surface of the substrate (12), - a protective encapsulation (160, 162a, 162b, 20) sealingly encapsulating the substrate (12) and the light radiation source(s) (14), the encapsulation being light-permeable to facilitate propagation of light radiation from the device. The encapsulation includes thermally-conductive material (20) at the back surface of the substrate (12) .