Micro LED Interposer Testing for Batch Transfer and Repair
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Solution Overview
Problem
Conventional mass transfer techniques for micro LED arrays in display devices are inefficient due to miniaturization, leading to insufficient transfer efficiency as the size of display panels increases.
Innovation Solution
A display module configuration that includes a substrate with a driving circuit, an interposer with a testing circuit and electrically conductive structure, allowing for electrical testing and bonding of micro light emitting elements, and a method for repairing defective elements by separating and replacing the interposer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional mass transfer technique using mechanical robot arms or laser separation is used, then individual micro LEDs can be transferred, but transfer efficiency is insufficient to meet demands due to miniaturization and increasing display panel size
Solution Approach 1:
The patent merges multiple micro LED transfer operations into a single batch process by maintaining a temporary substrate that holds multiple micro LEDs, allowing simultaneous transfer of multiple elements to the target substrate, thereby dramatically improving transfer efficiency
Solution Approach 2:
The patent introduces a temporary substrate as an intermediary carrier that temporarily holds multiple micro LEDs before transfer. This intermediary enables batch processing and simplifies the transfer mechanism by allowing one-to-many transfer operations instead of sequential one-to-one transfers
2Reliability
If micro LEDs are transferred to target substrate without pre-testing, then transfer process is simpler, but defective elements cannot be identified and cause quality issues
Solution Approach 1:
The patent implements preliminary electrical testing of micro LEDs on the temporary substrate before the actual transfer to the target substrate. This preliminary action identifies defective elements in advance, allowing selective transfer of only qualified micro LEDs, thereby ensuring quality without compromising the overall process efficiency
Solution Approach 2:
The patent segments the transfer process into distinct phases: testing phase on temporary substrate, selection phase based on test results, and transfer phase to target substrate. This segmentation allows quality control to be integrated without complicating the overall transfer mechanism
3Ease of repair
If defective micro LEDs are repaired by heating the target substrate, then defective elements can be replaced, but thermal damage occurs to the target substrate and driving circuit
Solution Approach 1:
The patent uses the temporary substrate as a mediator for repair operations. Defective micro LEDs can be re-heated and re-transferred from the temporary substrate without subjecting the target substrate and its driving circuit to high temperatures, thereby enabling repair while avoiding thermal damage to sensitive components
Solution Approach 2:
The patent separates the repair function from the target substrate by maintaining the temporary substrate as a dedicated repair and re-transfer platform. This segmentation confines thermal effects to the temporary substrate during repair operations, protecting the target substrate and driving circuit from thermal damage
Data Source
AI summary
A display module includes a substrate, an interposer and at least one micro light emitting element. The substrate has a driving circuit. The interposer includes an interlayer, a testing circuit and an electrically conductive structure. The testing circuit and the electrically conductive structure are located at the interlayer, and the driving circuit is electrically connected with the electrically conductive structure. The micro light emitting element is located at the interposer. The micro light emitting element is electrically connected with the testing circuit and the electrically conductive structure.