Stacked LED Unit Pixel With Inclined Sidewalls to Prevent Cracks
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Solution Overview
Problem
Conventional LED displays face challenges in manufacturing unit pixels with stacked blue, green, and red light emitting devices, leading to increased height and susceptibility to cracks in insulation and metal layers during the manufacturing process.
Innovation Solution
The unit pixel design includes a first, second, and third light emitting stack with inclined side surfaces at angles between 30 to 70 degrees, adhesive layers with similar angles, and contact electrodes with angled sidewalls, enhancing adhesion and preventing cracks, while maintaining electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If blue, green, and red light emitting devices are stacked to form unit pixels, then the number of light emitting devices per pixel is reduced and manufacturing efficiency is improved, but the overall height of the unit pixel is increased and insulation layers or metal layers are easily cracked during manufacturing
Solution Approach 1:
The patent applies curvature by forming the light emitting stacks with inclined side surfaces instead of vertical walls. This curved/angled geometry distributes mechanical stress more evenly during manufacturing processes, preventing crack formation in the insulation and metal layers while maintaining the stacked configuration that improves manufacturing efficiency.
Solution Approach 2:
The patent changes the geometric parameters of the light emitting stacks by specifying inclination angles between 30-60 degrees for the side surfaces. This parameter modification optimizes the structural integrity during manufacturing while preserving the space-saving stacked architecture, thereby resolving the contradiction between manufacturing efficiency and crack resistance.
2Manufacturing precision
If individual light emitting devices are arranged on each sub-pixel, then color accuracy is maintained, but the number of light emitting devices increases and mounting time is significantly extended
Solution Approach 1:
The patent merges multiple light emitting devices (blue, green, and red) into a single stacked structure that functions as one unit pixel. This combining approach maintains the full-color capability by integrating all three color-emitting devices vertically, while dramatically reducing the number of separate mounting operations required, thus resolving the time-consuming issue without sacrificing color accuracy.
Solution Approach 2:
The patent transitions from a two-dimensional arrangement of light emitting devices to a three-dimensional stacked configuration. By utilizing the vertical dimension, the patent consolidates multiple devices into a compact stack, maintaining color functionality while reducing the footprint and mounting complexity, thereby addressing both color accuracy and manufacturing time concerns.
Data Source
AI summary
A unit pixel including a first light emitting stack; a second light emitting stack disposed under the first light emitting stack, and having an area greater than that of the first light emitting stack; a third light emitting stack disposed under the second light emitting stack, and having an area greater than that of the second light emitting stack, in which at least one of the first through third light emitting stacks includes a side surface having an inclination angle within a range of about 30 degrees to about 70 degrees with respect to a first plane parallel to a top surface of the third light emitting stack.