Micro-LED Display Module Simultaneous Transfer Bonding
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Solution Overview
Problem
The existing roll-to-roll process for mounting micro-LED chips on a mount substrate is inefficient due to separate transfer and bonding steps, leading to low throughput and increased defects, and thermal expansion of the substrate during solder heating causes dislocation of micro-LED chips.
Innovation Solution
Simultaneous transfer and bonding of micro-LED chips to a mount substrate using a planar carrier member with heated solders, where thermal expansion is suppressed by a suction chuck to maintain substrate flatness and precision, allowing reliable bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If separate transfer and bonding steps are used in roll-to-roll process, then device complexity is reduced, but productivity is lowered
Solution Approach 1:
The patent combines the transfer process and bonding process into a single integrated simultaneous transfer and bonding (STB) system. The planar carrier member transfers micro-LED chips to the mount substrate while solder reflow bonding occurs at the same time, eliminating the need for separate sequential steps and thereby increasing productivity without significantly increasing device complexity
2Productivity
If simultaneous transfer and bonding is performed, then productivity is increased, but manufacturing precision deteriorates due to substrate bending
Solution Approach 1:
The patent applies preliminary anti-action by using a suction chuck to apply negative pressure to the mount substrate before and during the solder heating process. This pre-counteracts the thermal expansion forces that would cause substrate bending, preventing dislocation of micro-LED chips and maintaining manufacturing precision even during simultaneous transfer and bonding operations
Solution Approach 2:
The patent changes the physical state of the mount substrate by applying suction pressure to counteract thermal expansion. By modifying the pressure parameter during the heating process, the substrate remains flat and prevents chip dislocation, thereby maintaining positioning accuracy while enabling simultaneous transfer and bonding
3Strength
If solder heating temperature is increased for reliable bonding, then bonding strength is improved, but thermal expansion of substrate increases causing chip dislocation
Solution Approach 1:
The suction chuck applies negative pressure to the mount substrate to counteract the thermal expansion forces generated during high-temperature solder heating. This preliminary counter-action prevents substrate bending and maintains chip alignment even at elevated temperatures required for strong bonding
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 increases production efficiency and ensures precise, reliable bonding of micro-LED chips without substrate deformation, improving color uniformity and reducing defects.
Implementation Method 1
the mount substrate is bent by thermal expansion at a solder heating temperature
Implementation Method 2
the negative pressure is created in each of the pneumatic holes, whereby the micro-LED chip is attached to the lower surface of the quartz plate by the negative pressure
Implementation Method 3
the solders are heated simultaneously with the transfer of the micro-LED chips to bond the micro-LED chips to the mount substrate
Data Source
AI summary
Disclosed is a method for constructing a micro-LED display module. The method includes: retaining micro-LED chips in a matrix on a chip retaining member; picking up the micro-LED chips on the chip retaining member and transferring the picked up micro-LED chips to a planar carrier member; pressing the micro-LED chips on the planar carrier member against a mount substrate; and heating solders disposed on the mount substrate above the melting point of the solders simultaneously with the pressing of the micro-LED chips against the mount substrate to bond the micro-LED chips to the mount substrate. The mount substrate is sucked by a suction chuck during heating of the solders.