Micro LED Pixel Stacking on IC Backplanes for Compact RGB Layout
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Solution Overview
Problem
Traditional micro LED pixel structures face challenges in reducing dimensions while maintaining a high light emitting area, often requiring external panels for electrode connection which increases pixel size.
Innovation Solution
The micro LED pixel design incorporates an integrated circuit (IC) backplane with three staggered light emitting mesas, each connected to a bottom pad on the backplane, eliminating the need for an external panel and allowing for reduced cross-sectional dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If micro LED mesas are arranged side by side to form a micro LED panel, then the light emitting area is maintained, but the pixel dimensions increase
Solution Approach 1:
The patent transitions from a two-dimensional side-by-side arrangement of micro LED mesas to a three-dimensional stacked configuration along the vertical axis. Multiple light emitting mesas are positioned at different heights above the IC backplane, utilizing the vertical dimension to increase light emitting area without expanding the horizontal pixel footprint.
Solution Approach 2:
The patent implements a nested structure where multiple light emitting mesas are vertically stacked and interconnected through electrical connecting structures. The mesas are arranged in a compact hierarchical configuration, with each mesa nested within the vertical space defined by the pixel structure, maximizing space utilization.
2Reliability
If external panels are used to connect electrodes for micro LED mesas, then electrical connection is achieved, but the pixel dimensions increase
Solution Approach 1:
The patent merges the electrode connection function into the vertical stacked structure by integrating electrical connecting structures within the pixel body. The bottom electrical connecting structures connect lower mesas to the IC backplane, while top electrical connecting structures connect upper mesas, eliminating the need for separate external panels and incorporating all electrical connections within the compact pixel dimensions.
Solution Approach 2:
The patent introduces intermediate electrical connecting structures (bottom electrical connecting structures and top electrical connecting structures) that serve as mediators between the light emitting mesas and the IC backplane. These intermediate connection elements enable reliable electrical connectivity without requiring external panel extensions, bridging the electrical gap within the vertical stack.
3Volume of stationary object
If multiple micro LED mesas are formed vertically with a common central axis, then pixel volume is reduced, but light emitting area is limited
Solution Approach 1:
The patent employs asymmetric positioning of light emitting mesas relative to the central vertical axis. Instead of all mesas being perfectly aligned concentrically, the mesas are offset at different horizontal positions, allowing multiple mesas to be packed vertically without excessive overlap, thereby increasing the effective light emitting area while maintaining compact pixel volume.
Data Source
AI summary
A micro LED pixel includes an integrated circuit (IC) backplane; a first light emitting mesa provided on the IC backplane; a second light emitting mesa provided above the first light emitting mesa, a part of the second light emitting mesa not covering the first light emitting mesa; a third light emitting mesa provided above the second light emitting mesa, a part of the third light emitting mesa not covering the first light emitting mesa or the second light emitting mesa; a first bottom electrical connecting structure configured to connect a bottom surface of the part of the second light emitting mesa and the IC backplane; a second bottom electrical connecting structure configured to connect a bottom surface of the part of the third light emitting mesa and the IC backplane; and an optical isolation structure provided around at least part of the micro LED pixel.