Micro LED Display Assembly Using Fluxed Conductive Adhesive
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Solution Overview
Problem
The existing display modules face challenges in achieving reliable bonding strength between micro light emitting diodes (LEDs) and substrate electrode pads, which affects the overall performance and durability of the display.
Innovation Solution
A display assembly is designed with an adhesive layer comprising a non-conductive polymer resin, a flux agent, and conductive particles, where the flux agent improves wetting properties and the conductive particles, including first and second conductive particles, ensure strong electrical connections between the LEDs and substrate electrode pads, using materials like tin, silver, and gold, and having sizes ranging from 10 nm to 1 μm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional adhesive materials are used to bond micro LEDs to substrate electrode pads, then the bonding process is simple, but the bonding strength and electrical connectivity are insufficient
Solution Approach 1:
The adhesive layer is formulated as a composite material containing conductive particles (silver, copper, or aluminum) dispersed in an adhesive matrix. This composite structure provides both mechanical bonding strength and electrical conductivity simultaneously, resolving the contradiction between strong bonding and sufficient electrical connectivity without requiring separate bonding and conductive layers.
Solution Approach 2:
The adhesive layer performs multiple functions simultaneously: it provides mechanical bonding between the micro LED and substrate, establishes electrical connectivity through conductive particles, and ensures proper positioning. This multi-functionality eliminates the need for separate bonding and conductive layers, maintaining process simplicity while achieving both strong bonding and reliable electrical connection.
2Reliability
If the adhesive layer contains only non-conductive polymer resin, then the material composition is simple, but the electrical connectivity between LEDs and substrate pads is insufficient
Solution Approach 1:
The adhesive layer incorporates conductive particles (silver, copper, or aluminum) with electrical conductivity of at least 10^-5 S/m dispersed in an adhesive matrix. This composite structure provides both mechanical bonding and electrical connectivity, resolving the contradiction between simple material composition and sufficient electrical connectivity for reliable device operation.
3Reliability
If no flux agent is added to the adhesive layer, then the manufacturing process is simpler, but the wetting property and bonding reliability are poor
Solution Approach 1:
The adhesive layer incorporates a flux agent that undergoes chemical changes during the bonding process to improve wetting properties. The flux agent modifies the surface energy and chemical composition at the bonding interface, enabling reliable bonding between the micro LED and substrate electrode pad. This chemical parameter change resolves the contradiction between bonding reliability and manufacturing simplicity.
4Reliability
If the conductive particles have large size, then the electrical conductivity is higher, but the bonding precision and connection reliability are reduced
Solution Approach 1:
The conductive particles are controlled within a specific size range of 0.1 μm to 10 μm, optimizing the balance between electrical conductivity and bonding precision. This parameter control ensures sufficient electrical connectivity while maintaining accurate positioning and reliable bonding, resolving the contradiction between conductivity and precision.
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 solution enhances the bonding strength and electrical connectivity between the LEDs and substrate pads, improving the display's reliability, efficiency, and contrast ratio by preventing light reflection and minimizing color mixing, thereby extending the product's lifespan and maintaining high brightness and resolution.
Implementation Method 1
The flux agent may be made of a material that improves wetting property of the plurality of conductive particles
Implementation Method 2
a plurality of conductive particles dispersed in the non-conductive polymer resin and connecting the electrodes of the light emitting diodes and the plurality of electrode pads
Data Source
AI summary
Provided is a display assembly including a plurality of light emitting diodes, a plurality of electrodes provided on the plurality of light emitting diodes, a substrate, a plurality of electrode pads provided on the substrate, the plurality of electrode pads being connected to the electrodes provided on the plurality of light emitting diodes, and an adhesive layer fixing the plurality of light emitting diodes to the substrate, wherein the adhesive layer includes a non-conductive polymer resin, a flux agent mixed with the non-conductive polymer resin, and a plurality of conductive particles dispersed in the non-conductive polymer resin and connecting the electrodes of the light emitting diodes and the plurality of electrode pads.