Pixelated LED Chip Underfill Structure for Lower Pixel Cross-Talk
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Solution Overview
Problem
Conventional LED array devices face challenges in achieving small pixel pitches due to difficulties in preventing emission overlap between adjacent LEDs, ensuring homogeneity, and maintaining high light utilization efficiency.
Innovation Solution
The use of underfill materials with improved surface coverage, wetting layers to enhance the flow of underfill materials, and protruding or textured features on pixels helps to reduce cross-talk, improve homogeneity, and maintain light utilization efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If smaller pixel pitches are implemented in LED arrays, then image resolution is improved, but emission overlap between adjacent LEDs increases
Solution Approach 1:
A light-guiding structure is introduced as an intermediary element between adjacent LEDs. This structure receives light from one LED and guides it to a specific exit point, preventing direct emission overlap with adjacent LEDs while maintaining small pixel pitches for high image resolution
Solution Approach 2:
The light path is redirected from a horizontal planar path to a three-dimensional path through the light-guiding structure. By utilizing the vertical dimension and lateral surfaces of the structure, light from adjacent LEDs is spatially separated, eliminating emission overlap while preserving small pixel pitch configurations
2Object-generated harmful factors
If light segregation structures are added to prevent emission overlap, then contrast is improved, but light utilization efficiency decreases
Solution Approach 1:
The light-guiding structure serves as an efficient light transport intermediary with high light extraction efficiency. It captures light that would otherwise be lost or cause cross-talk and redirects it to productive exit points, maintaining high light utilization while preventing pixel interference
Solution Approach 2:
Complex mechanical light blocking structures are replaced with an optical guidance system that actively directs light flow. This substitution maintains energy efficiency by guiding rather than blocking light, preserving luminous efficacy while achieving pixel segregation
3Ease of manufacture
If conventional pick-and-place techniques are used for mounting LED components, then manufacturing is simplified, but reliability in high-density arrays deteriorates
Solution Approach 1:
Multiple LED mounting operations are merged into a single wafer-level process. LEDs are mounted in array form onto the light-guiding structure substrate using wafer-level techniques, then the entire array is transferred as one unit, simplifying the manufacturing process while ensuring uniform, reliable connections across all high-density positions
4Area of stationary object
If discrete LED arrays with multi-color LEDs are used for large format displays, then viewing distance is increased, but pixel pitch becomes too large for medium-sized displays
Solution Approach 1:
The display is segmented into modular light-guiding structure units that can be manufactured with small pixel pitches using wafer-level techniques. These modular units are then assembled to create large-format displays, achieving both fine pixel pitch and large overall display area
Solution Approach 2:
The display architecture transitions from planar arrangement to three-dimensional integration using light-guiding structures. This enables higher density packing of pixels while maintaining large display area, achieving small pixel pitch suitable for medium-sized displays with enhanced resolution
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 enhances contrast and inter-pixel illumination homogeneity while facilitating efficient manufacturability, thereby overcoming limitations of conventional LED array devices.
Implementation Method 1
providing wetting layers to improve wicking or flow of underfill materials within pixelated light emitting diodes (LEDs)
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
Pixelated-LED chips and related methods are disclosed. A pixelated- LED chip (130) includes an active layer with active layer portions (84-1, 84-2, 84-3) arranged on or over a light-transmissive substrate (15). The active layer portions, which may be independently electrically accessible, are configured to illuminate different light- transmissive substrate portions (86-1, 86-2, 86-3) to form pixels (104a, 104b, 104c). Various enhancements may beneficially provide increased contrast (i.e., reduced cross-talk between pixels) and/ or promote inter-pixel illumination homogeneity, without unduly restricting light utilization efficiency. In some aspects, an underfill material (108) with improved surface coverage is provided between adjacent pixels (104a, 104b, 104c) of a pixelated-LED chip (130). The underfill material (108) may be arranged to cover all lateral surfaces between the adjacent pixels. In some aspects, discontinuous substrate portions are formed before application of underfill materials. In some aspects, a wetting layer (128) is provided to improve wicking or flow of underfill materials (108) during various fabrication steps.