Flexible LED Strip Interposer Layout for Precise Positioning

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Solution Overview

Problem

The accurate positioning of light-emitting diodes on electrical conductors in flexible LED bands is complex due to their length and stress, making it difficult to achieve reliable connections for automotive applications.

Innovation Solution

A method for producing a flexible lighting strip with light-emitting diodes arranged in a longitudinal configuration using wire segments with circular cross-sections that can absorb compressive and tensile stress, allowing for precise soldering and mechanical symmetry, and potentially using interposers with light-emitting diodes mounted on them, connected via laser welding or other welding processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If light-emitting diodes are positioned directly on long electrical conductors, then the lighting strip can be produced, but the positioning accuracy deteriorates due to conductor length and stress

Engineering Contradiction:
Improvepositioning accuracy of light-emitting diodesVSAvoidcomplexity of positioning process
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent divides the continuous electrical conductor into discrete conductor sections, each associated with a specific light-emitting diode or group of diodes. This segmentation allows each section to be precisely positioned and soldered independently, eliminating the cumulative positioning errors that occur with long continuous conductors. The conductor sections are arranged in a comb-like pattern that facilitates accurate alignment during the molding process.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a comb-like structure as an intermediary element that holds both the conductor sections and light-emitting diodes in predetermined positions. This comb structure acts as a positioning template or fixture during assembly, ensuring that conductors and diodes align accurately without requiring complex manual positioning procedures. The comb structure is integrated into the mold, making it a permanent part of the lighting strip assembly.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If conventional conductor arrangements are used, then the structure is simple, but the reliability deteriorates under thermomechanical stress

Engineering Contradiction:
Improvereliability under thermomechanical stressVSAvoidcomplexity of conductor configuration
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces flexible zones in the conductor arrangement that can dynamically adapt to thermomechanical stresses. These flexible zones allow the conductor structure to deform elastically under stress rather than fracturing, maintaining electrical connectivity during thermal cycling and mechanical bending. The comb-like structure inherently provides this flexibility through its geometric configuration, allowing controlled movement while maintaining structural integrity.

Inventive Principle:
Principle #15Dynamics

3Ease of manufacture

If asymmetric conductor arrangements are used, then positioning may be simplified, but mechanical symmetry and stress distribution deteriorate

Engineering Contradiction:
Improveease of positioningVSAvoidmechanical symmetry
Core Design Contradiction:
Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent employs asymmetric conductor sections within the symmetric comb structure, where individual conductor segments have different lengths or configurations optimized for their specific positioning tasks. This controlled asymmetry allows each conductor section to be precisely tailored for its function while the overall comb structure maintains mechanical symmetry for balanced stress distribution. The asymmetric positioning elements are integrated into the symmetric mold design, combining both advantages.

Inventive Principle:
Principle #4Asymmetry

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

The solution enables high-accuracy positioning and improved reliability of light-emitting diodes, allowing the flexible lighting strip to withstand thermomechanical stress tests and meet automotive application requirements.

Implementation Method 1

at least one of the wire segments of the outer lines is bent building zones that are capable to receive compressive and/or tensile stress

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

The method comprises the steps of soldering a first functional element to a first wire segment and connecting of the at least one wire segment to a second functional element

Methodology Applied
Scientific EffectSoldering: Soldering

Implementation Method 3

The at least one wire segment is connected to the second wire segment by laser welding

Methodology Applied
Scientific EffectLaser welding: Laser Beam Welding

Data Source

PatentEP3824219B1Flexible light-emitting diode lighting strip with interposer
Publication Date: 2023.11.08 LUMILEDS HLDG BV
  • EP3824219B1 patent drawingFigure 1
  • EP3824219B1 patent drawingFigure 2
  • EP3824219B1 patent drawingFigure 3

AI summary

The invention describes a method for producing a flexible lighting strip (100) comprising a multitude of functional elements (21) in a longitudinal arrangement. The functional elements (21) comprise light-emitting diodes (22). In one alternative, the functional elements (21) may be light-emitting diodes (22) itself. In another alternative, the functional elements (21) may be interposers (24) with light-emitting diodes (22) mounted thereon. The functional elements (21) are arranged in at least two groups. Each group comprises at least two functional elements (21) arranged in an electrical series connection. The at least two groups are arranged in an electrical circuit having at least an anode track (12) and a cathode track (14) as outer lines (12, 14), wherein the at least two functional elements (21) are arranged in an electrical parallel connection to the anode track (12) and the cathode track (14). The at least two groups are arranged in a longitudinal arrangement such that a last functional element (21) of a first group is arranged next to a first functional element (21) of a second group. Each of the outer lines (12, 14) consists of a wire line having substantially circular wires (30), whereby the wires (30) of the outer lines (12, 14) are bent building zones that are capable to receive compressive and/or tensile stress. The electrical circuit provides a third wire line (15) having a substantially circular wire (30) as a center line arranged between the outer lines (12, 14). The method comprises the steps of soldering a first functional element (21) to a first wire segment and connecting of the at least one wire segment to a second functional element.