Micro-LED Relay Substrate for Defective Chip Exchange
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Solution Overview
Problem
In the manufacturing of micro-LED display apparatuses, defective chips are difficult to remove from the driving substrate without damaging surrounding chips due to strong solder bonding, leading to inefficiencies in chip exchange and repair processes.
Innovation Solution
A method involving the formation of micro-LED chips on a relay substrate with exposed chip-side electrodes, where defective chips are identified and replaced using a resin material like silicone resin, allowing for easy transfer and bonding to a driving substrate without flux, using a temperature lower than the solder melting point for initial bonding and subsequent reflow for secure attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If micro-LED chips are firmly bonded to the driving substrate by soldering, then bonding strength is improved, but chip replaceability deteriorates
Solution Approach 1:
The patent introduces an intermediate relay substrate that segments the bonding process into two distinct stages: first bonding chips to the relay substrate with replaceability in mind, then transferring to the driving substrate for final secure attachment. This segmentation allows defective chips to be replaced on the relay substrate before final bonding, resolving the contradiction between strong bonding and easy replacement.
Solution Approach 2:
The patent performs preliminary bonding of micro-LED chips to the relay substrate before final transfer to the driving substrate. This preliminary action allows for inspection and replacement of defective chips on the relay substrate, which is designed to facilitate chip removal. After preliminary bonding and inspection, the relay substrate is transferred to the driving substrate for final secure attachment, thus achieving both replaceability during manufacturing and strong final bonding.
2Reliability
If defective chips are removed from the driving substrate, then product quality is improved, but surrounding chips may be damaged
Solution Approach 1:
The patent segments the manufacturing process into two phases: preliminary bonding on a relay substrate where defective chips can be safely replaced, and final transfer to the driving substrate. By performing defective chip removal on the relay substrate rather than the driving substrate, the harmful effects are isolated to the relay substrate which can be discarded, protecting the driving substrate and surrounding good chips from damage.
Solution Approach 2:
The relay substrate acts as an intermediary between chip production and final product assembly. It provides a temporary platform where defective chips can be replaced without risking damage to the final driving substrate. The relay substrate absorbs the harmful effects of chip removal and replacement operations, then transfers only the good chips to the driving substrate, thus protecting the final product from damage.
3Reliability
If flux is used during bonding, then bonding reliability is improved, but void formation at bonding interface increases
Solution Approach 1:
The patent extracts the flux application step from the bonding process by using a eutectic metal layer instead. The eutectic metal layer provides the necessary bonding facilitation without introducing flux that would cause void formation. This extraction of the harmful element (flux) while maintaining the beneficial function (bonding reliability) resolves the contradiction between bonding reliability and void formation.
Solution Approach 2:
The patent changes the bonding parameters by using a eutectic metal layer with specific composition and thickness control. The eutectic metal layer is designed with controlled thickness (e.g., 1-10 μm) and specific eutectic composition that enables reliable bonding at lower temperatures and pressures without requiring flux. This parameter change eliminates flux-related void formation while maintaining bonding reliability.
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 enables efficient and damage-free exchange of defective chips, reducing bonding defects and improving the yield of high-quality micro-LED modules suitable for durable applications by minimizing voids at the bonding interface and facilitating easier chip replacement.
Implementation Method 1
The forming the plurality of micro-LED chips on the relay substrate further includes attaching the plurality of micro-LED chips with a resin material formed on the relay substrate.
Implementation Method 2
bonding the chip-side electrode to the driving substrate-side electrode
Implementation Method 3
heating the chip-side electrode and the driving substrate-side electrode to a temperature lower than or equal to a solder melting temperature
Implementation Method 4
compressing the chip-side electrode and the driving substrate-side electrode via the solder
Implementation Method 5
heating the driving substrate onto which each of the plurality of micro-LED chips is compressed to a temperature equal to or higher than the solder melting temperature for reflow
Implementation Method 6
At least one of eutectic metal between the solder and the chip-side electrode or eutectic metal between the solder and the driving substrate-side electrode is formed by the reflow.
Data Source
AI summary
A method of manufacturing a display apparatus, a display apparatus, and a structure for manufacturing a display apparatus are provided. The method of manufacturing a display apparatus includes: forming a micro-light-emitting diode (LED) chip on a relay substrate such that a chip-side electrode is exposed; transferring the micro-LED chip from the relay substrate to a driving substrate including a driving substrate-side electrode; and bonding the chip-side electrode to the driving substrate-side electrode.