Micro-LED Batch Transfer With Adhesive Height Compensation
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Solution Overview
Problem
The existing manufacturing process of Micro-LED display devices faces challenges in transferring miniaturized, high-density LED grains to a circuit substrate, particularly in reducing or eliminating the height difference between the LED grains and the target substrate, which affects displaying efficiency and luminous performance.
Innovation Solution
A micro-LED transfer method involving a donor substrate with LED grains arranged in an array and a pasting substrate with a hot melt adhesive film, where the pasting substrate is aligned and heated to transfer the LED grains to a target substrate, simultaneously filling the height difference with the melted adhesive to reduce or eliminate it.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional LED grain transfer methods are used, then LED grains can be transferred to the target substrate, but the height difference between the LED grains and the target substrate cannot be reduced or eliminated
Solution Approach 1:
The patent introduces a pasting substrate as an intermediary carrier between the donor substrate and the target substrate. The pasting substrate includes a bottom plate and a hot melt adhesive film that temporarily holds the LED grains during transfer. This intermediary structure enables precise height control by allowing the adhesive film thickness to compensate for the height difference between LED grains and the target substrate, while maintaining high transfer efficiency through batch processing.
Solution Approach 2:
The patent changes the physical state of the hot melt adhesive film from solid to liquid through heating, and then back to solid through cooling. By controlling the temperature parameters (heating to melt the adhesive, then cooling to solidify it), the process achieves both high transfer efficiency during the liquid state and precise height control during the solid state, resolving the contradiction between transfer efficiency and height difference reduction.
2Manufacturing precision
If miniaturized high-density LED grains are transferred, then display resolution is improved, but the difficulty of mass transfer increases
Solution Approach 1:
The patent merges multiple transfer operations into a single batch process. By arranging multiple miniaturized LED grains on the donor substrate and transferring them simultaneously to the target substrate using the pasting substrate, the method achieves high arrangement precision for high-density displays while reducing process complexity compared to individual grain transfer methods.
Solution Approach 2:
The pasting substrate serves multiple functions: it acts as a temporary carrier for LED grains, provides height compensation through the adhesive film, enables batch processing for high-density arrays, and facilitates precise alignment with the target substrate. This multi-functional design resolves the contradiction between handling miniaturized grains and maintaining process simplicity.
3Illumination intensity
If the hot melt adhesive film is used to fill the height difference, then the luminous performance is enhanced, but the manufacturing process complexity increases
Solution Approach 1:
The patent utilizes the phase transition of the hot melt adhesive film (solid-liquid-solid) to achieve height difference compensation. The adhesive is applied in solid form, heated to liquid form for filling and bonding, then cooled to solid form for structural stability. This phase transition approach enhances luminous performance by eliminating height differences while maintaining relatively simple manufacturing processes through standard thermal processing.
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 enables the simultaneous transfer of multiple LED grains, reducing the difficulty of mass transfer and improving displaying efficiency by eliminating the height difference between the LED grains and the target substrate, thereby enhancing the luminous performance.
Implementation Method 1
heating the pasting substrate pasted with the plurality of LED grains to a first temperature to melt the hot melt adhesive film
Implementation Method 2
the first temperature being greater than or equal to a melting temperature of the hot melt adhesive film
Data Source
AI summary
A micro-LED transfer method, including: moving a passing substrate to a position above a donor substrate and moving the pasting substrate in a direction approaching the donor substrate to paste up LED grains so that the LED grains are separated from the bearing substrate; moving the pasting substrate with the LED grains to a position above a target substrate with the LED grains being closer to the target substrate than the pasting substrate, and conducting an alignment so that the LED grains are directly opposite to positions on the target substrate where the LED grains are to be arranged; and heating the pasting substrate with the LED grains to a first temperature greater than or equal to a melting temperature of the hot melt adhesive film to melt the hot melt adhesive film, so that the LED grains are separated from the pasting substrate and transferred to the target substrate.