Planarization Layer for Uniform Laser Lift-Off in Flexible OLED Panels
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Solution Overview
Problem
The laser lift-off process in manufacturing flexible OLED display panels is hindered by uneven laser distribution due to mechanical damage on the glass carrier, leading to damage of the OLED element and reduced yield.
Innovation Solution
A method involving the formation of a planarization layer with high laser transmittance and low roughness on the glass carrier to ensure uniform laser distribution during the lift-off process, using materials like silicon dioxide and organic silicon, which helps in separating the glass carrier from the flexible substrate without damaging the touch circuit or TFT.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser lift-off process is performed directly on glass carrier with mechanical damage, then the separation process can be initiated, but uneven laser distribution occurs causing damage to OLED element and reduced yield
Solution Approach 1:
A planarization layer is introduced as an intermediary between the glass carrier and the flexible substrate. This layer serves as a mediator that absorbs and distributes laser energy uniformly, preventing direct transmission of uneven laser distribution to the flexible substrate and OLED elements, thereby protecting them from damage while enabling successful separation.
Solution Approach 2:
The planarization layer is formed on the glass carrier surface before the laser lift-off process. This preliminary action creates a protective and planarizing interface that ensures uniform laser distribution during the subsequent separation process, preventing damage to the flexible substrate and OLED elements before they are exposed to laser energy.
2Reliability
If laser energy is increased to ensure separation in damaged regions, then separation can be achieved, but damage to touch circuit and TFT increases
Solution Approach 1:
The planarization layer acts as a protective intermediary that absorbs excess laser energy and distributes it uniformly across the glass carrier surface. This prevents localized energy concentration that would otherwise damage the touch circuit and TFT on the flexible substrate, while still enabling complete separation through controlled energy distribution.
Solution Approach 2:
The planarization layer changes the laser energy distribution parameters by absorbing and scattering the laser light uniformly across the glass carrier surface. This parameter modification ensures that sufficient energy is delivered for complete separation while preventing localized energy concentration that would cause damage to sensitive components.
3Object-affected harmful factors
If laser energy is reduced to protect flexible substrate, then damage to touch circuit is minimized, but separation of PI and glass carrier fails
Solution Approach 1:
The planarization layer serves as a protective intermediary that allows the use of lower laser energy settings. It absorbs and distributes the reduced laser energy uniformly, ensuring complete separation of the flexible substrate from the glass carrier while preventing damage to the touch circuit and TFT on the flexible substrate.
Solution Approach 2:
The planarization layer modifies the laser energy transmission parameters, enabling the use of lower energy settings that are safe for the flexible substrate. The layer's optical properties ensure that sufficient energy is still delivered to achieve complete separation while maintaining the safety of sensitive components.
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 method enhances the success rate of the laser lift-off process and improves the yield of flexible OLED display panels by ensuring uniform laser distribution and preventing damage to the substrate components.
Implementation Method 1
using the laser passing through the glass carrier and modify the flexible substrate (ex: PI) and separate to the glass
Implementation Method 2
the planarization layer has laser transmittance ≥90% in 300-400 nm wavelength range
Implementation Method 3
on the region has more laser distribution, many ashes produced of PI by laser burning, it may damage the circuit and TFT
Data Source
AI summary
A method of manufacturing flexible OLED display panel is provided. The method comprises following steps. Providing a glass carrier, sequentially forming a flexible substrate, a low temperature poly-Si layer and OLED element layer on a surface of the glass carrier; forming a planar layer on a second surface of the glass carrier which is away from the flexible substrate and obtaining a planning OLED display panel; removing the glass carrier by laser lift-off the planning OLED display panel and obtaining the flexible OLED display panel. The method could reduce the problem of lower peeling successful rate caused by the unevenly distributing in the flexible substrate during the laser lift-off process.