Micro LED Electrode Extension Layout for Reliable Mass Bonding
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Solution Overview
Problem
The miniaturization of micro LEDs leads to short-circuiting and bonding failures during the mass transfer and bonding process to the display back plate, resulting in dark spots and reduced yield due to the close proximity of electrodes and potential damage to the epitaxial structure.
Innovation Solution
The micro LED display device design features bonding structures that are in direct contact with extended electrode portions, ensuring a long distance between bonding structures to prevent short-circuiting and maintaining the epitaxial structure's integrity by avoiding overlap with the epitaxial structure's projection on the display back plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If micro LED structures are miniaturized to reduce display device size, then the display device achieves smaller dimensions and higher pixel density, but the distance between electrodes is shortened and electrode area is reduced, leading to short-circuiting and bonding failures during mass transfer
Solution Approach 1:
The electrode structure is segmented into a main electrode body and an extended portion. The extended portion projects beyond the epitaxial structure's orthogonal projection, creating a distinct bonding region that is spatially separated from the epitaxial structure. This segmentation allows the bonding structure to contact only the extended portion, preventing short-circuiting while maintaining miniaturization.
Solution Approach 2:
The electrode structure extends in the horizontal direction (parallel to the display back plate) beyond the vertical projection of the epitaxial structure. This dimensional extension creates a bonding region that is laterally displaced from the epitaxial structure, allowing bonding structures to contact electrodes without overlapping the epitaxial structure's projection, thus preventing short-circuits during bonding.
2Productivity
If multiple micro LED structures are subjected to mass transfer process with close proximity, then production efficiency is improved, but phenomena such as short-circuiting of electrodes or bonding failure are prone to occur
Solution Approach 1:
The electrode extended portions are pre-configured to project beyond the epitaxial structure's orthogonal projection before the bonding process. This preliminary geometric configuration ensures that during mass transfer and bonding operations, the bonding structures will naturally contact only the extended portions, preventing short-circuits without requiring precise real-time alignment control.
3Device complexity
If bonding structures are positioned close to electrodes for efficient bonding, then bonding process is simplified, but the two bonding structures may contact each other causing short-circuiting
Solution Approach 1:
The bonding function is extracted and concentrated onto the electrode extended portions, which are spatially separated from the epitaxial structure. By making the extended portions contact the bonding structures while preventing contact between bonding structures, the design extracts the bonding function from the main electrode body and places it in a safe, isolated location that prevents short-circuits.
Data Source
AI summary
A micro LED display device includes a display back plate having a first connecting electrode and a second connecting electrode, a micro LED structure disposed on the display back plate, and a first bonding structure and a second bonding structure disposed between the display back plate and the micro LED structure. The micro LED structure includes an epitaxial structure, and a first electrode and a second disposed on the side of the epitaxial structure closest to the display back plate. The orthogonal projections of the extension portions of the first electrode and the second electrode both exceed the orthogonal projection of the epitaxial structure on the display back plate. Neither the orthogonal projection of the first bonding structure nor the orthogonal projection of the second bonding structure overlaps the orthogonal projection of the bottom surface of the epitaxial structure on the display back plate.