Subpixel LED Transfer Layout for High-Density Direct View Displays
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for fabricating subpixel light emitting diodes (LEDs) for direct view display devices face challenges in efficiently transferring LEDs of different colors to a backplane without physical interference and optimizing LED density on growth substrates, leading to increased production costs and complexity.
Innovation Solution
The method involves providing LEDs of different colors on separate substrates, forming transfer structures with varying thicknesses of reflective and solder layers, and using laser irradiation to bond and separate LEDs from the substrates, allowing for precise placement on a backplane without interference, thereby increasing LED density and reducing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If LEDs of different colors are transferred simultaneously to a backplane, then production efficiency is improved, but physical interference between LEDs of different heights prevents successful bonding
Solution Approach 1:
The patent applies preliminary action by forming sacrificial solder layers of different thicknesses on LEDs of different colors before transfer. Thicker sacrificial layers are created on taller LEDs (e.g., red LEDs) and thinner layers on shorter LEDs (e.g., blue LEDs). This preliminary differentiation in layer thickness allows simultaneous transfer to occur without physical interference, as the taller LEDs with thicker sacrificial layers can be bonded first, creating space for subsequent bonding of shorter LEDs.
Solution Approach 2:
The patent applies local quality by making the sacrificial solder layer thickness location-dependent based on LED color and height. Different regions of the substrate receive different thicknesses of sacrificial material - for example, red LED regions receive thicker sacrificial layers while blue LED regions receive thinner layers. This localized variation in material thickness enables selective bonding sequences and prevents physical interference during simultaneous transfer operations.
2Ease of manufacture
If LED density on growth substrates is increased, then production cost is reduced, but difficulty in transferring and placing LEDs without interference increases
Solution Approach 1:
The patent reduces transfer process complexity by performing preliminary actions on the growth substrate before LED transfer. Sacrificial solder layers of varying thicknesses are formed on LED regions corresponding to different colors, and isolation structures are created to define bonding sequences. This preliminary structuring enables high-density LED arrays to be transferred systematically without interference, maintaining ease of manufacture even at high densities.
Solution Approach 2:
The patent introduces sacrificial solder layers as intermediary materials between the LEDs and the backplane. These intermediary layers of different thicknesses act as temporary spacers that prevent physical interference during transfer. After bonding, the sacrificial layers are removed, leaving the LEDs properly positioned. This intermediary approach simplifies the transfer of high-density LED arrays by providing a controlled mechanism for managing LED heights and bonding sequences.
3Reliability
If LEDs are transferred in multiple separate batches, then physical interference is avoided, but production time increases
Solution Approach 1:
The patent enables simultaneous transfer of multiple LED colors by performing preliminary actions to create different sacrificial layer thicknesses before transfer. This preliminary differentiation allows the transfer process to proceed in a single batch rather than multiple separate batches, significantly reducing production time while maintaining transfer accuracy through the structured bonding sequence enabled by varying layer thicknesses.
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 enables efficient transfer and placement of LEDs of different colors on a backplane, enhancing display performance and reducing manufacturing costs by increasing LED density on growth substrates and minimizing physical interference during the transfer process.
Implementation Method 1
using laser irradiation to bond and separate LEDs from the substrates
Implementation Method 2
The laser beam 467 may be directed onto the solder layer 431, 441 to heat and melt the solder layer(s) 431, 441
Data Source
AI summary
A method includes transferring a first subset of the first LEDs from a first substrate to a first backplane to form first subpixels in pixel regions, transferring a first subset of the second LEDs to a second backplane and separating the first subset of the second LEDs from a second substrate to leave first vacancies on the second substrate, forming an additional electrically conductive material on a second subset of second LEDs located on the second substrate after transferring the first subset of the second LEDs to the second backplane, positioning the second substrate over the first backplane, such that the first subpixels are disposed in the first vacancies, and transferring the second subset of the second LEDs to a second subset of bonding structures on the first backplane to form second subpixels in the pixel regions, while a gap exists between the first subpixels and the second substrate.