Micro-LED Display Assembly Structure for Uniform DEP Transfer
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Solution Overview
Problem
Large-area micro-LED displays face challenges in quickly and accurately transferring millions of micro-LEDs to a display panel, leading to low transfer yield due to increased error rates and uneven dielectrophoresis (DEP) force.
Innovation Solution
A display device structure that eliminates the need for solder metal by using a substrate with first and second assembling wirings, a partition wall with a hole, and a semiconductor light-emitting device with a step difference part on its side portion, where a connection electrode is disposed on the step difference part to enhance electrical contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If self-assembly method is used to transfer micro-LEDs, then transfer speed is improved, but transfer error rate increases causing low transfer yield
Solution Approach 1:
The patent introduces an intermediary structure (the hole in the partition wall and the step difference part) that mediates between the micro-LED and the substrate. This intermediary structure guides the micro-LED into the correct position during self-assembly, reducing transfer errors while maintaining high transfer speed through automated processes.
Solution Approach 2:
The patent creates an equipotential environment by designing the hole and step difference part to provide uniform electrical and mechanical conditions across all micro-LED assembly positions. This ensures consistent self-assembly behavior for all micro-LEDs, reducing variation in transfer quality and improving overall transfer yield.
2Extent of automation
If DEP force is used for self-assembly, then assembly is achieved, but uneven DEP force causes low self-assembly rate
Solution Approach 1:
The patent applies local quality by designing the hole and step difference part with specific local characteristics that concentrate and uniformize the DEP force distribution. The hole geometry and step structure create localized electric field conditions that enhance the self-assembly rate by ensuring uniform DEP force action on each micro-LED.
3Extent of automation
If DEP force is used for self-assembly, then assembly is achieved, but semiconductor light-emitting device becomes slanted causing deteriorated electrical contact characteristics
Solution Approach 1:
The step difference part creates an equipotential mechanical interface that ensures uniform contact pressure and electrical contact conditions. This structure compensates for the slanting effect by providing a geometric constraint that guides the micro-LED into proper alignment, maintaining excellent electrical contact characteristics despite the automated self-assembly process.
4Strength
If solder metal is used for contact bonding, then bonding is achieved, but low melting point causes poor deposition and uneven roughness leading to poor contact
Solution Approach 1:
The patent extracts and eliminates the solder metal layer from the contact bonding structure. By removing this problematic intermediate layer with its low melting point and deposition issues, the invention achieves direct contact bonding between the micro-LED and the substrate through the step difference part, eliminating poor contact and uneven roughness while maintaining strong bonding.
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 improves electrical and optical characteristics, increases luminance, reduces power consumption, and enhances product reliability by expanding the electrical contact area and eliminating the need for solder metal, thereby preventing brightness deviations and tilt failures.
Implementation Method 1
In related technologies, a self-assembly transfer process using dielectrophoresis (DEP) is being attempted
Data Source
AI summary
A display device can include a substrate, a first assembling wiring on the substrate, a second assembling wiring on the substrate, a partition wall disposed on the first and second assembling wirings and having a hole, a semiconductor light-emitting device disposed in the hole and having a first step difference part on a side portion thereof, and a connection electrode disposed on at least the first step difference part.