Micro LED Display Encapsulation via Softened Film and Micro Structures
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Solution Overview
Problem
Micro LED displays face challenges with micro LED chips easily falling off due to weak adhesion forces, especially on flexible substrates, and existing package methods either result in uneven surfaces or increased costs with additional coating processes.
Innovation Solution
A package method involving a softened encapsulation film that is pressed onto the micro LED chips and substrate, using micro structures on the chips to enhance adhesion and eliminate the need for additional coating, ensuring even surfaces and improved stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If micro LED chips are bonded to substrate using only conductive bonding layer, then manufacturing process is simple, but adhesion force is weak causing chips to fall off
Solution Approach 1:
The patent uses a composite structure combining conductive bonding material with transparent encapsulation material. The encapsulation material forms a protection layer that integrates both mechanical support and electrical conduction functions, creating a composite bonding system that enhances chip adhesion while maintaining process simplicity.
Solution Approach 2:
The transparent encapsulation material serves multiple functions simultaneously: it provides mechanical adhesion to prevent chip detachment, acts as a conductive path for electrical signals, and forms a protective barrier. This multi-functional layer eliminates the need for separate bonding and protection layers.
2Reliability
If three micro LED chips are encapsulated to form larger modules, then adhesion force increases, but gaps between modules cause surface unevenness
Solution Approach 1:
The patent employs a thin film encapsulation approach where a continuous transparent encapsulation layer is formed over individual micro LED chips rather than grouping them into modules. This thin film provides uniform coverage that maintains surface flatness while ensuring adequate adhesion strength for each chip.
Solution Approach 2:
Instead of combining multiple chips into single modules, the patent applies encapsulation to each micro LED chip individually. This segmentation approach allows precise control over each chip's encapsulation layer thickness and adhesion, eliminating the surface unevenness caused by gaps between larger modules.
3Reliability
If encapsulation glue is applied by coating process, then protection layer is formed, but additional apparatus and process increase cost
Solution Approach 1:
The patent utilizes the transfer substrate itself as the encapsulation application tool. The transparent encapsulation material is already present on the transfer substrate, and the mass transfer process automatically deposits it onto the target substrate along with the micro LED chips, eliminating the need for separate coating apparatus.
Solution Approach 2:
The patent combines the chip transfer process with the encapsulation material deposition process. Both operations are performed simultaneously in a single mass transfer step, merging two previously separate processes (chip placement and encapsulation application) into one integrated operation that reduces equipment requirements.
4Reliability
If encapsulation glue is coated on flexible substrate, then protection layer is formed, but coating control becomes difficult during bending
Solution Approach 1:
The encapsulation material is pre-applied to the transfer substrate before the mass transfer process. This preliminary action ensures that the encapsulation layer is already in place and properly controlled on a rigid substrate, avoiding the difficulties of attempting to coat and control viscous material on a flexible, bending substrate during the transfer operation.
5Device complexity
If non-uniform coating thickness of encapsulation glue is used, then cost is reduced, but light emission becomes uneven
Solution Approach 1:
The patent employs a thin film encapsulation approach where a continuous transparent encapsulation layer is formed with uniform thickness. This thin film provides consistent optical properties across the display surface, ensuring uniform light emission while maintaining a relatively simple formation process through the mass transfer technique.
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 method provides enhanced stability and even surfaces for micro LED displays by tightly combining the encapsulation film and micro LED chips, reducing costs by omitting the additional coating process and improving light extraction.
Implementation Method 1
a package method involving a softened encapsulation film that is pressed onto the micro LED chips and substrate
Implementation Method 2
A light-emitting surface of each of the micro LED chips is set with at least one micro structure... The top ends of the micro structures are located in a light-emitting surface of the encapsulation film
Data Source
AI summary
A micro light-emitting diode (micro LED) display and a package method thereof are described. The micro LED display includes a substrate, various micro LED chips, and an encapsulation film. The substrate includes a wire. The micro LED chips are disposed on a surface of the substrate and are electrically connected to the wire. A light-emitting surface of each of the micro LED chips is set with at least one micro structure, and each micro structure has a top end. The encapsulation film encapsulates the micro LED chips, and covers the surface of the substrate. The top ends of the micro structures are located in a light-emitting surface of the encapsulation film.