Micro-LED Chip Rework Using Adhesive Transfer for Precise Alignment
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Solution Overview
Problem
Conventional techniques such as pick and place or individual transfer using ejector pins are inadequate for ultra-small LED chip arrays due to miniaturization of chip sizes and narrowed spacings, leading to difficulties in swift and accurate transfer and a high risk of misalignment defects from vibrations or shocks.
Innovation Solution
The ultra-small LED chip rework apparatus employs a transfer technique using stick-shaped press heads with adhesive layers of varying strengths to rapidly and accurately remove defective chips and replace them with new ones, improving alignment and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pick and place or individual transfer using ejector pins is used for ultra-small LED chip arrays, then transfer of LED chips can be performed, but misalignment defects occur due to vibrations or shocks and transfer accuracy deteriorates
Solution Approach 1:
The patent introduces a transfer tape as an intermediary carrier between the LED chip array and the substrate. The transfer tape with adhesive layer captures multiple ultra-small LED chips simultaneously and transports them to the substrate for transfer, eliminating the need for individual chip handling that is susceptible to vibrations and shocks. This intermediary approach maintains transfer accuracy while enabling batch processing.
2Productivity
If conventional individual transfer methods are used for ultra-small LED chips, then chip transfer can be achieved, but cycle time is long and process efficiency is low
Solution Approach 1:
The patent merges multiple individual chip transfer operations into a single batch transfer process. By adhering multiple ultra-small LED chips to a transfer tape simultaneously and transferring them together to the substrate in one operation, the method dramatically reduces the number of sequential steps required, thereby shortening cycle time and improving overall process efficiency.
3Speed
If stick-shaped press head with adhesive layer is used for transfer, then transfer speed and accuracy are improved, but device complexity increases
Solution Approach 1:
The patent employs a flexible transfer tape with adhesive layer as the core transfer mechanism. This thin film approach allows the press head to conform to the substrate surface and maintain consistent adhesive contact across multiple chips, enabling fast and accurate transfer without requiring complex mechanical positioning systems or multiple actuators.
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 significantly reduces cycle time, enhances process efficiency and precision, and improves yield by allowing on-site repair of misaligned ultra-small LED chips, overcoming limitations of traditional methods.
Implementation Method 1
a second adhesive layer at a lower end of the stick-shaped detach press head, the second adhesive layer having a stronger adhesion than the first adhesive layer
Implementation Method 2
a third adhesive layer at a lower end of the stick-shaped attach press head, the third adhesive layer having a weaker adhesion than the first adhesive layer
Data Source
AI summary
An ultra-small LED chip rework apparatus using a transfer technique according to the present invention is characterized by including a detach press head in a stick-shaped configuration with a second adhesive layer stronger than a first adhesive layer at the lower end and capable of transferring a defective ultra-small LED chip attached to the first adhesive layer to the second adhesive layer by applying pressure to the upper surface of the defective ultra-small LED chip, and a driving unit that moves the detach press head on the substrate in the X, Y, and Z-axis directions.