Micro-LED Electrode Layout for Upside-Down Transfer Tolerance
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Solution Overview
Problem
During the transfer process of inorganic light-emitting diodes to an array substrate, the light-emitting devices may be mounted upside down, leading to defective pixels and increased manufacturing costs due to the time-consuming discovery and repair of these defects.
Innovation Solution
A light-emitting device design with a specific electrode structure, including upper, side, and lower portions that extend through a passivation layer to ensure electrical connection to the array substrate even when the device is upside down, and a display apparatus with an adhesive layer and pad electrodes to facilitate this connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the light-emitting device is transferred using a conventional electrode structure, then the transfer process is simple, but the device may be mounted upside down causing defective pixels
Solution Approach 1:
The patent applies asymmetry by creating an electrode structure where the first electrode extends further in the first direction than the second electrode extends in the second direction. This asymmetric design ensures that regardless of the device orientation during transfer, at least one electrode will properly contact the corresponding pad electrode on the array substrate, preventing defective pixels while maintaining simple transfer processes.
2Ease of manufacture
If the light-emitting device is mounted upside down, then manufacturing time increases due to defect discovery and repair, but the electrode structure could be designed to prevent this
Solution Approach 1:
The patent implements preliminary action by designing the electrode structure in advance with unequal extensions in different directions. This pre-designed asymmetric structure proactively prevents the upside-down mounting problem before it occurs, eliminating the need for time-consuming defect discovery and repair processes while keeping the transfer process simple and straightforward.
3Ease of manufacture
If symmetric electrode structure is used, then manufacturing is easier, but electrical connection fails when device is inverted
Solution Approach 1:
The patent resolves this contradiction by introducing asymmetry in the electrode design where the first electrode has a greater extension length in the first direction compared to the extension length of the second electrode in the second direction. This asymmetric configuration maintains fabrication simplicity while achieving orientation independence, allowing the device to maintain proper electrical connection regardless of how it is mounted on the array substrate.
Data Source
AI summary
Disclosed is a display apparatus including a light-emitting device having a light-emitting structure including a first semiconductor layer, an active layer and a second semiconductor layer, a passivation layer covering surfaces of the light-emitting structure. The light-emitting device includes at least one first electrode coupled to the first semiconductor layer and at least one second electrode coupled to the second semiconductor layer. A first electrode includes a first upper portion extending through the passivation layer to contact the first semiconductor layer, a first side portion, and a first lower portion on a portion of a side surface and a lower surface of the light-emitting structure, respectively. A second electrode includes a second upper portion extending through the passivation layer to contact the second semiconductor layer, a second side portion and a second lower portion on a portion of the side surface and the lower surface of the light-emitting structure, respectively.