LED Mass Transfer via Insulating Adhesive Columns
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Solution Overview
Problem
The existing transfer methods for micro LED chips to display backplanes are costly, cumbersome, and prone to alignment issues, leading to weak welding strength and potential chip failure or abnormal connections.
Innovation Solution
A method involving the application of an insulating-adhesive between LED chips on a growth substrate, which forms columns upon heating, allowing direct transfer of LED chips onto a display backplane, ensuring precise alignment and bonding with reduced material usage and process complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple transfer steps are used to move LED chips from growth substrate to display backplane, then chip coverage can be achieved, but alignment precision deteriorates and welding strength becomes weak
Solution Approach 1:
The transfer process is segmented into two independent stages: first transferring LED chips from growth substrate to intermediate substrate, then from intermediate substrate to display backplane. Each stage uses dedicated alignment features (first alignment features on growth substrate, second alignment features on intermediate substrate) to ensure precise positioning at each step, preventing cumulative alignment errors that would occur in a single multi-step process.
Solution Approach 2:
An intermediate substrate is introduced as a mediator between the growth substrate and the display backplane. This intermediate substrate serves as a stable transfer platform that maintains alignment precision during the transfer process. The intermediate substrate includes alignment features that interface with both the growth substrate and the display backplane, ensuring accurate positioning throughout the multi-stage transfer.
2Quantity of substance
If multiple transfer steps are used, then chip coverage can be achieved, but process complexity increases and costs rise
Solution Approach 1:
The complex transfer process is segmented into standardized, repeatable stages that can be independently optimized and controlled. Each stage (growth substrate to intermediate substrate, then to display backplane) is a self-contained transfer operation with its own alignment and bonding procedures, making the overall complex process manageable through modular standardization.
Solution Approach 2:
Alignment features are pre-formed on both the growth substrate and the intermediate substrate before the transfer process begins. These pre-formed alignment features (first alignment features and second alignment features) eliminate the need for complex real-time alignment adjustments during transfer, reducing process complexity while ensuring accurate chip placement.
3Quantity of substance
If LED chips are transferred multiple times, then coverage can be achieved, but reliability deteriorates due to potential misalignment and weak welding
Solution Approach 1:
Alignment features are pre-formed on both the growth substrate and the intermediate substrate before the transfer process begins. These pre-formed alignment features (first alignment features and second alignment features) eliminate the need for complex real-time alignment adjustments during transfer, reducing process complexity while ensuring accurate chip placement.
Solution Approach 2:
The intermediate substrate serves as a cushioning platform that protects LED chips during transfer. By providing a stable, pre-aligned intermediate platform, the system cushions against potential misalignment and mechanical stress that would otherwise directly affect the final welding quality between chips and display backplane.
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 transfer process, reduces costs, ensures strong welding, and prevents chip failure by providing precise alignment and bonding, thus ensuring normal connections between LED chips and drive circuits.
Implementation Method 1
An insulating-adhesive column is formed between the growth substrate and the display backplane by softening the insulating-adhesive through heating
Implementation Method 2
the softened insulating-adhesive subjected to heating is adhered to the display backplane
Data Source
AI summary
A method for mass transfer, a light-emitting diode (LED) display device, and a display apparatus are provided. The method includes: applying an insulating-adhesive on a growth substrate, where the insulating-adhesive applied is between two adjacent LED chips; placing the growth substrate above a display backplane, where a distance between the growth substrate and the display backplane after placing is greater than a height of an LED chip; forming an insulating-adhesive column between the growth substrate and the display backplane by softening the insulating-adhesive through heating, where the softened insulating-adhesive subjected to heating is adhered to the display backplane; separating the LED chip from the growth substrate, to make the separated LED chip fall onto a corresponding pad-group through a channel formed by insulating-adhesive columns around the separated LED chip; and bonding the fallen LED chip with the corresponding pad-group on the display backplane.