Micro LED Display RDL Layout to Prevent Transfer Splitting
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Solution Overview
Problem
Micro light emitting diode display units lack structural support during transfer processes, leading to bending, splitting, and reduced yield due to insufficient support strength without a transparent hard substrate and insulating layers without metal layers.
Innovation Solution
A redistribution layer with staggered gaps between electrode and pad patterns, connected by conductive through holes, enhances structural support and reduces splitting, using an insulating layer with controlled exposure to improve reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the micro light emitting diode display unit is transferred from the epitaxial substrate to the film layer without a transparent hard substrate, then the flexibility and ease of transfer are improved, but the structural strength and resistance to bending and splitting deteriorate
Solution Approach 1:
The display unit is divided into multiple independent sub-pixel regions (red, green, blue sub-pixels) that are electrically and structurally segmented. Each sub-pixel has its own electrode patterns and insulating layer configuration, allowing independent support and reducing stress concentration that would cause splitting during transfer.
Solution Approach 2:
The insulating layer is selectively disposed in specific regions between electrode patterns rather than uniformly across the entire structure. This local quality approach provides structural support exactly where needed (between adjacent electrode patterns) while maintaining flexibility in other areas, preventing splitting during transfer without compromising ease of manufacture.
2Adaptability or versatility
If metal layers are removed from some regions of the micro light emitting diode display unit, then the electrical insulation and design flexibility are improved, but the support strength and structural reliability deteriorate
Solution Approach 1:
An insulating layer is introduced as an intermediary structure between electrode patterns in regions where metal layers are removed. This insulating layer provides both electrical insulation (enabling design flexibility) and mechanical support (compensating for the removed metal layers), resolving the contradiction between adaptability and strength.
3Reliability
If the insulating layer is completely covered by metal layers, then the electrical connectivity and current distribution are improved, but the manufacturing complexity and risk of short circuits during transfer increase
Solution Approach 1:
The metal layer is extracted or removed from regions directly above the insulating layer between electrode patterns, while maintaining metal layers in other necessary regions for electrical connectivity. This selective extraction simplifies the manufacturing process by reducing the number of metal deposition steps and lowers the risk of short circuits during transfer, while electrical connectivity is maintained in functional areas.
Data Source
AI summary
A light emitting display unit includes a redistribution layer (RDL) and multiple light emitting elements. The RDL includes multiple electrode patterns, multiple pad patterns, an insulating layer and multiple conductive through holes. A first gap and a second gap are respectively formed between two adjacent electrode patterns and between corresponding two adjacent pad patterns. A third length of the overlapping area of an orthographic projection of the first gap on the pad patterns and the pad patterns in a first direction is less than or equal to a second length of the second gap in the first direction. The micro light emitting elements are disposed on the RDL and electrically connected with the electrode patterns.