Micro-LED Active Matrix Layout Without Substrate Thinning

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Solution Overview

Problem

The manufacturing process of micro-LED displays is complex and costly due to the need for multiple substrate transfers and thinning operations to position LEDs with their emitting surface opposite the electrical contacts, leading to reduced yield and limited assembly temperatures and pressures.

Innovation Solution

A micro-LED display design featuring a support plate with integrated power supply planes and conductive elements that connect µLED chips to an active matrix, eliminating the need for contacts on the emission face and reducing the number of power supplies, with a transparent blade carrying the active matrix to ensure efficient light transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If multiple substrate transfers and thinning operations are performed to position LED emitting surface opposite electrical contacts, then light transmission is improved, but manufacturing complexity and cost increase

Engineering Contradiction:
Improvelight transmissionVSAvoidmanufacturing process complexity
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The patent inverts the conventional LED structure by placing the emitting surface on the same side as the electrical contacts. This inversion eliminates the need for substrate thinning and multiple transfers, as the emitting surface is naturally positioned on the front side where contacts are already located, thereby simplifying the manufacturing process while maintaining light transmission capability

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent extracts and eliminates the substrate thinning and multiple transfer operations from the manufacturing process. By designing the LED with the emitting surface on the same side as the contacts, the complex steps of substrate removal, thinning, and repositioning are completely removed, reducing manufacturing complexity and cost

Inventive Principle:
Principle #2Taking out (Extraction)

2Illumination intensity

If substrate thinning or removal is performed to allow light transmission, then light emission is improved, but manufacturing yield decreases and component embrittlement occurs

Engineering Contradiction:
Improvelight emissionVSAvoidmanufacturing yield
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent inverts the LED structure so that the emitting surface is on the same side as the electrical contacts. This eliminates the need for substrate thinning or removal, thereby preventing component embrittlement and maintaining high manufacturing yield while still achieving effective light emission

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent performs the emitting surface positioning action during the initial LED fabrication process, before any potential damage can occur. By designing the LED with the emitting surface on the front side from the outset, there is no need for subsequent substrate removal or thinning operations that could cause embrittlement or reduce yield

Inventive Principle:
Principle #10Preliminary action

3Illumination intensity

If multiple substrate transfers are performed to position LED emitting surface opposite contacts, then light transmission is improved, but manufacturing cost increases

Engineering Contradiction:
Improvelight transmissionVSAvoidmanufacturing cost
Core Design Contradiction:
Illumination intensityVSEase of manufacture

Solution Approach 1:

The patent inverts the conventional LED structure by placing the emitting surface on the same side as the electrical contacts. This eliminates the need for multiple substrate transfers and thinning operations, significantly reducing manufacturing cost while maintaining effective light transmission

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent extracts and eliminates the multiple substrate transfer and thinning operations from the manufacturing process. By designing the LED with the emitting surface on the front side, these costly manufacturing steps are completely removed, reducing overall manufacturing cost

Inventive Principle:
Principle #2Taking out (Extraction)

4Ease of manufacture

If substrate thinning is performed to allow color conversion layers to be made on emitting side, then color conversion is improved, but component embrittlement occurs

Engineering Contradiction:
Improvecolor conversion layer fabricationVSAvoidcomponent strength
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The patent inverts the LED structure so that the emitting surface is on the same side as the electrical contacts. This allows color conversion layers to be applied directly on the emitting surface without requiring substrate thinning, thereby maintaining component strength while enabling effective color conversion

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent performs the color conversion layer application during the initial LED fabrication process, before any substrate manipulation that could cause embrittlement. By having the emitting surface on the front side from the outset, color conversion layers can be applied early in the process when the substrate is still intact and strong

Inventive Principle:
Principle #10Preliminary action

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 simplifies the manufacturing process, reduces contact and power supply complexity, and enhances the display's efficiency by minimizing manufacturing steps and improving light transmission, thereby reducing costs and increasing yield.

Implementation Method 1

each μLED chip comprising several light-emitting diodes, each μLED chip comprising a substrate comprising on its lower part a conductive surface acting as a common electrode and on its upper part the μLEDs and their electrical control contacts

Methodology Applied
Scientific EffectLight emission: Light Emitting Diode

Data Source

PatentEP4082040B1Micro-led display emitting through the active matrix
Publication Date: 2024.05.01 THALES SA
  • EP4082040B1 patent drawingFigure 1~2
  • EP4082040B1 patent drawingFigure 3~4

AI summary

The invention relates to a display comprising a plurality of electronic chips (10) with μLEDs and an active matrix (40) for controlling the chips, the active matrix being mounted on a transparent slide (2), each chip comprising a plurality of electroluminescent diodes (13), each chip comprising a substrate (11) comprising an electrode (12) which is common to the μLEDs and, on the upper portion thereof, the μLEDs and their electrical control contacts (14). The display comprises: one or more power supply planes (20) arranged on the upper face of a support plate (1); the plurality of electronic chips, first conductive elements (30) providing the electrical connections between the common electrodes of each chip and the power supply planes; the transparent slide (2) bearing the active matrix, second conductive elements (31) providing the electrical connections between the electrical contacts of the electronic chips and the electrical contacts (41) for controlling the active matrix.