Flux Structure Layer for Micro-LED Alignment and Contact
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Solution Overview
Problem
In micro-LED displays, the mass transfer technology for transferring micro light-emitting diodes from the growth substrate to the pixel array substrate often results in alignment issues, leading to incorrect electrical connections and functional failures due to shifting of micro light-emitting diodes during transposition.
Innovation Solution
A pixel array substrate design that includes a flux structure layer surrounding the conductive structure and light-emitting diode, with a manufacturing method involving a flux material layer that softens below the melting temperature of the conductive material, ensuring accurate electrical connection and alignment of light-emitting diodes with contact pads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mass transfer technology is used to transfer micro light-emitting diodes from growth substrate to pixel array substrate, then productivity is improved, but manufacturing precision deteriorates due to alignment issues and shifting during transposition
Solution Approach 1:
The flux material layer acts as an intermediary substance between the conductive material and the light-emitting diode during the mass transfer process. When heated, the flux material softens and creates a viscous medium that allows the light-emitting diode to self-align with the contact pad while preventing lateral shifting, thus maintaining alignment accuracy during high-productivity mass transfer operations
Solution Approach 2:
The invention changes the temperature parameter during the transfer process. By heating the substrate to a temperature where the flux material softens (but remains below the melting point of the conductive material), the system transitions from a rigid state to a controlled viscous state that enables precise alignment without compromising the structural integrity of the conductive elements
2Reliability
If heating is applied to melt conductive material for electrical connection, then electrical conductivity is improved, but manufacturing precision deteriorates due to potential deformation and misalignment
Solution Approach 1:
The invention carefully controls the temperature parameter by using a flux material with a softening temperature lower than the melting temperature of the conductive material. This parameter differentiation allows the flux to soften and enable alignment while the conductive material remains solid and maintains its shape and position, ensuring both electrical connection and alignment accuracy
Solution Approach 2:
The flux material serves as a thermal intermediary that undergoes phase change at a lower temperature than the conductive material. This intermediary layer absorbs and distributes heat uniformly, enabling the conductive material to form reliable electrical connections through controlled softening without reaching its melting point and causing deformation
3Manufacturing precision
If flux material layer is used to improve alignment, then manufacturing precision is improved, but device complexity increases due to additional material layers and process steps
Solution Approach 1:
The flux material layer performs multiple functions simultaneously: it acts as an alignment medium during transfer, serves as a protective barrier during heating, facilitates thermal distribution, and prevents contamination. This multi-functionality reduces the need for separate components or process steps, thereby limiting the increase in device complexity while achieving improved manufacturing precision
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 design increases the probability of correct electrical connections between light-emitting diodes and contact pads, reduces light reflections, and improves display quality by maintaining light extraction efficiency and preventing flux material overlap on contact pads.
Implementation Method 1
forming a flux material layer on the substrate, and the flux material layer at least partially covers each of the first conductive materials, wherein the flux material layer has a softening temperature lower than the melting temperature of the first conductive material; heating the substrate so as to bring the flux material layer to the softening temperature
Implementation Method 2
heating the substrate to bring each of the first conductive materials to the melting temperature to form a first conductive structure
Data Source
AI summary
A pixel array substrate has a plurality of sub-pixel regions, wherein a pixel structure of an individual sub-pixel region includes a first signal line, a second signal line, a first contact pad, a second contact pad, a light-emitting diode, a first conductive structure, and a flux structure layer. The first contact pad and the second contact pad are respectively electrically connected with the first signal line and the second signal line. The light-emitting diode is disposed on the first contact pad. A portion of the first conductive structure is disposed between the first contact pad and a first electrode of the light-emitting diode. The flux structure layer partially surrounds the first conductive structure and the light-emitting diode. A top portion of the flux structure layer is higher than a top surface of the first electrode and is lower than a bottom surface of a light-emitting layer of the light-emitting diode.