Floating LED Carrier Design for Thermal Expansion Stress

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Solution Overview

Problem

Strip-lighting lamp assemblies face issues with crack formation and breakage due to different thermal expansion behaviors between light source printed circuit boards and heat sinks, leading to high tension at their connection points.

Innovation Solution

A light source mount design where the light source printed circuit board is rigidly connected to the heat sink at a central area and connected in a floating manner at two opposing end regions, allowing for relative movement and reducing thermal expansion-related stress while maintaining a secure thermal connection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the light source printed circuit board is rigidly connected to the heat sink at multiple points, then the thermal connection is secure, but high tension occurs due to different thermal expansion behaviors leading to crack formation or breakage

Engineering Contradiction:

Improvethermal connection reliabilityVSAvoidconnection strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The connection between the light source printed circuit board and heat sink is segmented into multiple independent connection points distributed across the board. Each connection point can move independently to accommodate thermal expansion differences, preventing stress concentration and crack formation while maintaining effective thermal contact.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The connection structure is designed to change its mechanical parameters (rigidity, contact pressure) in response to temperature changes. The floating connection allows the printed circuit board to expand and contract freely, while the thermal contact is maintained through elastic deformation of the connection elements, adapting to thermal expansion differences between materials.

Inventive Principle:

Principle #35Parameter changes

2Temperature

If the light source printed circuit board is rigidly connected to the heat sink, then thermal connection is secure, but relative movement is prevented causing stress during thermal expansion

Engineering Contradiction:

Improvethermal connection efficiencyVSAvoidthermal expansion adaptability

Core Design Contradiction:

TemperatureVSAdaptability or versatility

Solution Approach 1:

The connection system transitions from a static rigid connection to a dynamic floating connection that can adapt its configuration. The printed circuit board is allowed to move relative to the heat sink within certain limits, enabling the system to dynamically adjust to thermal expansion differences while maintaining thermal contact through spring-loaded or elastic connection elements.

Inventive Principle:

Principle #15Dynamics

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 effectively reduces the risk of crack formation and breakage by allowing differential thermal expansion while ensuring a robust and precise thermal connection, enhancing the reliability and longevity of the strip-lighting lamp assembly.

Implementation Method 1

at least one heat sink thermally connected to the light source printed circuit board

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

the light source printed circuit board and the heat sink have different thermal expansion behaviors (in particular due to the use of different materials having different thermal expansion coefficients)

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS10330288B2Lighting-means carrier for a strip-lighting luminaire

Publication Date: 2019.06.25 ZUMTOBEL LIGHTING GMBH

AI summary

The invention relates to a lighting-means carrier (5) for a strip-lighting luminaire, comprising: at least one lighting-means circuit board (30) having light-emitting diodes (33) that can be arranged thereon; and at least one heat sink (31) thermally connected to the lighting-means circuit board (30). In a central region, the lighting-means circuit board (30) is rigidly connected to the heat sink (31) in such a way that substantially no relative motion between the lighting-means circuit board (30) and the heat sink (31) is possible. In at least two further regions, the lighting-means circuit board (30) is connected to the heat sink (31) in a floating manner, the lighting-means circuit board (30) therefore being arranged on the heat sink (31) in such a way that the lighting-means circuit board can be moved in relation to the heat sink (31) outside of the central region. The invention further relates to a strip-lighting luminaire having at least one lighting-means carrier (5) according to the invention.