Micro LED Manufacturing via Cu Bump Bonding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The miniaturization of micro LEDs leads to narrow gaps between electrodes, causing short circuits due to Ni particle invasion and heat treatment issues during bonding, resulting in defective pixels and reduced yield in display module production.
Innovation Solution
A method involving the use of carbon nano tubes, graphene, or metal nano wires as conductive materials, along with a passivation element and a stepless bottom contact structure, to electrically connect the micro LEDs to a driving circuit layer without the need for heat treatment, eliminating the use of anisotropic conductive films and bump soldering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the chip size of micro LED is miniaturized, then the luminance efficiency and brightness are improved, but the gap between positive electrodes becomes too narrow causing short circuits due to Ni particle invasion
Solution Approach 1:
The patent removes the ACF and Ni particles from the bonding interface by using a direct bonding method with Cu bumps. This extraction eliminates the harmful Ni particles that cause short circuits while maintaining the miniaturized micro LED structure for high luminance efficiency.
Solution Approach 2:
The patent introduces Cu bumps as an intermediary bonding element between the micro LED and the substrate. These Cu bumps provide both mechanical support and electrical connection, replacing the problematic ACF/Ni particle system and preventing short circuits in miniaturized devices.
2Reliability
If bonding is performed through ACF or bump soldering, then the electrical connection is achieved, but heat treatment process causes cracks and misalignment of micro LEDs
Solution Approach 1:
The patent performs preliminary alignment of the micro LED with the Cu bumps before bonding. This pre-alignment ensures precise positioning is achieved before the bonding process, preventing misalignment issues that would otherwise occur during heat treatment.
Solution Approach 2:
The patent replaces the thermal bonding process (heating) with a mechanical bonding approach using Cu bumps. This substitution eliminates the heat treatment step that causes cracks and misalignment, while still achieving reliable electrical connection through the conductive Cu bumps.
3Ease of manufacture
If ACF is used as binder, then the connection of contact metals is facilitated, but the process complexity and heat treatment requirements increase
Solution Approach 1:
The patent extracts and removes the ACF layer from the bonding structure, replacing it with direct Cu bump bonding. This simplification eliminates the complex ACF material and its associated handling requirements, reducing overall process complexity while maintaining connection functionality.
Solution Approach 2:
The Cu bumps serve multiple functions simultaneously: they provide mechanical support, enable electrical connection, and facilitate thermal management. This multi-functionality replaces the specialized ACF binder, simplifying the overall structure and reducing process complexity.
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 approach enhances light emission efficiency, prevents short circuits, and improves production yield by simplifying the manufacturing process and eliminating the need for heat treatment, thereby reducing defects and costs.
Implementation Method 1
The conductive material may comprise at least one of carbon nano tube (CNT), graphene, or metal nano wire
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A display module and a manufacturing method thereof are provided. The manufacturing method may include forming an epitaxial film comprising a light emitting layer, a first type semiconductor layer, and a second type semiconductor layer, attaching the epitaxial film onto an intermediate substrate comprising a conductive material, patterning the epitaxial film to form a light emitting diode (LED) and electrically connecting the LED to a driving circuit layer through the conductive material.