μLED Strip Assembly on Backplane via Laser Lift-Off
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Solution Overview
Problem
Conventional methods for producing microLED arrays are costly and time-consuming due to the need for individual microLED device placement and polymer adhesion, which can damage these thin devices.
Innovation Solution
The method involves coupling strips of micro light emitting diodes (μLEDs) onto a backplane using fabrication substrates, which are then removed after attachment, allowing for a monolithic assembly that reduces handling and supports the μLEDs during placement, and utilizing a laser lift-off method for substrate removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If individual μLED devices are picked and placed onto a chip using conventional methods, then each device can be positioned, but the process is costly and time-consuming
Solution Approach 1:
The patent segments the μLED array into multiple strips that are fabricated separately on individual chips, then transferred and assembled on the backplane in a systematic sequence. This segmentation enables parallel processing of multiple strips simultaneously, dramatically improving productivity while maintaining precise positioning through structured transfer mechanisms.
Solution Approach 2:
The patent applies preliminary action by pre-fabricating complete μLED strips on separate chips before transfer, including pre-bonding multiple μLEDs to each chip in predetermined patterns. This preliminary preparation reduces the complexity and time of the final assembly process on the backplane, enabling faster production while preserving placement precision.
2Strength
If polymer adhesion is used to bind μLED devices to the chip, then devices can be attached, but the thin devices are damaged
Solution Approach 1:
The patent introduces an intermediary approach by using temporary adhesive layers that provide sufficient bonding strength during the transfer process, then allowing for clean removal without damaging the thin μLED devices. The intermediary adhesive enables controlled manipulation and positioning while protecting the fragile devices from mechanical stress.
Solution Approach 2:
The patent applies parameter changes by carefully controlling the adhesive properties, bonding pressure, and temperature parameters during the attachment process. By optimizing these parameters, the process achieves adequate bonding strength while minimizing mechanical stress and thermal damage to the thin μLED devices.
3Ease of operation
If strips of μLEDs are coupled onto backplane with fabrication substrates, then handling is easier and damage is reduced, but substrates must be removed after attachment
Solution Approach 1:
The patent applies preliminary action by attaching μLED strips to fabrication substrates before transfer, which provides mechanical support and enables easy handling during manipulation and positioning. The substrates serve as temporary carriers that simplify the transfer process, with their removal planned as a subsequent step after the strips are securely positioned on the backplane.
Solution Approach 2:
The fabrication substrates act as intermediary carriers that facilitate the transfer process. They provide a stable platform for handling the fragile μLED strips, enable precise positioning, and can be cleanly removed after the strips are bonded to the backplane, leaving no residue or damage.
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 simplifies the assembly process, reduces damage to μLEDs, and enables the efficient fabrication of μLED arrays for display devices, such as those used in virtual reality systems, by providing structural support and enabling easier handling and bonding.
Implementation Method 1
utilizing a laser lift-off method for substrate removal
Data Source
AI summary
Embodiments relate to fabricating a display device by assembling strips of μLED devices onto a backplane instead of individually picking and placing each μLED device onto the backplane. A strip of first μLED devices is coupled to a set of interconnections on the backplane. Then, the first fabrication substrate is removed from the strip of first μLED devices. A strip of second μLED devices producing another color (e.g., green) is attached to a second fabrication substrate. The strip of second μLED devices is coupled to another set of interconnections on the backplane. The process may be repeated for a strip of third μLED devices producing yet another color (e.g., blue). After attaching the second and third μLED devices, fabrication substrates on the second and third μLED devices are simultaneously removed by laser based lift-off (LLO) method.