Flexible Display Panel Bonding Region Thermal Expansion Mitigation
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Solution Overview
Problem
Flexible displays face bonding misalignment issues due to the high thermal expansion coefficient of flexible substrates, leading to attachment problems of integrated circuits during manufacturing.
Innovation Solution
A flexible display panel design incorporating a rigid substrate with a solder pad and a transition region where a second flexible substrate overlays the rigid substrate, along with a buffer and metal layer, to mitigate thermal expansion effects, combined with a method involving thermosetting polymer application, curing, and selective removal of the glass substrate to create a bonding region with a low thermal expansion coefficient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a flexible substrate is used throughout the display panel, then the panel achieves bendable characteristics and portability, but thermal expansion causes bonding misalignment of ICs on the solder pad
Solution Approach 1:
The patent applies different substrate materials to different regions: the display region uses flexible substrates for bendability, while the bonding region uses a rigid substrate with low thermal expansion coefficient for precise IC bonding. This local differentiation resolves the contradiction by giving each region the properties it needs.
Solution Approach 2:
The display panel is segmented into distinct regions with different substrate types. The bonding region is separated from the flexible display region, allowing independent optimization of each area's thermal and mechanical properties.
2Manufacturing precision
If a rigid substrate is used in the bonding region, then thermal expansion-induced misalignment is reduced, but the overall flexibility and portability of the display panel is compromised
Solution Approach 1:
The rigid substrate is localized only to the bonding region where precision is critical, while the rest of the panel maintains flexible substrates for overall bendability and portability.
Solution Approach 2:
The panel is divided into flexible and rigid zones, with the rigid substrate confined to the bonding area, allowing the majority of the panel to remain flexible.
3Device complexity
If the solder pad is formed directly on the flexible substrate, then the manufacturing process is simplified, but thermal expansion causes the solder pad to shift during IC bonding
Solution Approach 1:
The rigid substrate acts as an intermediary between the flexible substrate and the solder pad. It provides a stable thermal foundation for the solder pad while allowing the flexible substrate to maintain its bendable properties elsewhere.
Solution Approach 2:
The solder pad is formed on the rigid substrate rather than directly on the flexible substrate, creating a local area of thermal stability where precision bonding is required.
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
The solution enables a flexible display panel with bendable characteristics and a chip bonding region that minimizes thermal expansion-induced misalignment, effectively addressing the attachment challenges in flexible display manufacturing.
Implementation Method 1
curing the thermosetting polymer thereon into a solid film by baking
Implementation Method 2
removal of the solid film of the bonding region is performed by a dry etch or a laser lift-off means
Implementation Method 3
the buffer layer is formed by chemical vapor deposition means
Implementation Method 4
the metal layer is formed by physical vapor deposition means
Implementation Method 5
removal of the glass substrate outside the bonding region and the transition region is performed by at least one of laser cutting, cutter wheel cutting, and splitting means
Data Source
AI summary
A flexible display panel and a method for preparing thereof are provided. The method for preparing the flexible display panel includes providing a glass substrate and applying a thermosetting polymer on the glass substrate; curing the thermosetting polymer thereon into a solid film by baking; removing the solid film on a surface of a bonding region to expose a surface of the glass substrate underneath; forming a buffer layer on a surface of the solid film and the surface of the glass substrate from which the solid film has been removed; forming a metal layer on the buffer layer; forming a solder pad and metal wiring in the bonding region of the metal layer; attaching a chip to the solder pad of the bonding region after finishing bonding and sawing of a panel unit; and removing the glass substrate outside the bonding region and a transition region.