Micro-LED Bonding with SAP Bumps and Intermetallic Connections
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Solution Overview
Problem
The manufacturing method for display apparatuses using micro-LEDs is complex due to the need for stepped backplane substrates, which complicates the bonding process of light-emitting devices.
Innovation Solution
A method involving a source substrate structure with anisotropic conductive paste (SAP) is used to form bumps on micro-LEDs, allowing for simple and reliable bonding between the light-emitting devices and driving substrates, utilizing a two-layer structure of intermetallic compounds and adhesive layers for secure connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stepped portions are formed on the backplane substrate to connect light-emitting devices, then the light-emitting devices can be bonded to the backplane substrate, but the manufacturing process becomes complicated
Solution Approach 1:
The invention extracts the bonding function from the backplane substrate by introducing a separate transfer substrate. The light-emitting devices are bonded to the transfer substrate first, then transferred as a unit to the backplane substrate. This separation eliminates the need for stepped portions on the backplane substrate, simplifying its structure while maintaining bonding reliability.
Solution Approach 2:
The transfer substrate acts as an intermediary between the light-emitting devices and the backplane substrate. It provides a flat bonding surface for the devices and enables their transfer to the final destination without requiring complex modifications to the backplane substrate. The transfer substrate mediates the bonding process, allowing devices to be connected reliably while keeping the backplane substrate structure simple.
2Reliability
If stepped backplane substrate is used for bonding, then light-emitting devices can be connected, but manufacturing time increases
Solution Approach 1:
The invention performs preliminary bonding of light-emitting devices to the transfer substrate before final transfer to the backplane substrate. This preliminary action allows devices to be prepared and positioned in advance on a flat surface, simplifying the final bonding step and reducing overall manufacturing time compared to forming stepped portions and bonding devices individually.
Solution Approach 2:
The invention merges multiple light-emitting devices onto the transfer substrate in a single bonding operation, then transfers them collectively to the backplane substrate. This combining approach reduces the number of separate bonding operations required, thereby decreasing manufacturing time while maintaining reliable connections.
3Reliability
If stepped portions are formed on backplane substrate, then bonding can be achieved, but material waste increases
Solution Approach 1:
The invention extracts the bonding surface requirements from the backplane substrate by providing a separate transfer substrate with appropriate bonding features. This eliminates the need to modify the backplane substrate with stepped portions, reducing material usage and waste while achieving reliable bonding through the transfer substrate's structure.
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 method simplifies the manufacturing process, reduces material waste, and enhances the reliability and conductivity of connections between micro-LEDs and driving substrates, improving productivity and reducing costs, especially for high-resolution displays.
Implementation Method 1
A method involving a source substrate structure with anisotropic conductive paste (SAP) is used to form bumps on micro-LEDs
Implementation Method 2
Laser irradiation on the solder material portions can be employed to sequentially bond selected pairs of mated bonding structures
Implementation Method 3
The transferred devices can be pressed against the target substrate during a second reflow process
Implementation Method 4
utilizing a two-layer structure of intermetallic compounds and adhesive layers for secure connection
Implementation Method 5
utilizing a two-layer structure of intermetallic compounds and adhesive layers for secure connection
Data Source
Figure 1~6
Figure 7~9A
Figure 9B~9D
AI summary
A display apparatus, including a light-emitting device including a device-side electrode; a driving substrate configured to drive the light-emitting device; a driver-side electrode provided on the driving substrate; and a metal layer configured to connect the device-side electrode to the driver-side electrode, and including a first interface between the metal layer and the device-side electrode, and a second interface between the metal layer and the driver-side electrode, wherein at least one of the first interface and the second interface includes an intermetallic compound.