Flexible Substrate Auxiliary Bonding for Display Alignment

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Solution Overview

Problem

The challenge in flexible display technology is achieving a reliable and cost-effective bonding of electronic devices onto flexible substrates without compromising bonding precision and increasing production costs, as conventional methods either require rigid carriers or thicker, more expensive substrates that can lead to thermal expansion issues and bonding bubbles.

Innovation Solution

A flexible substrate with an auxiliary bonding portion integrally formed with the bonding portion, allowing the bonding portion to fall into the auxiliary region in an orthographic projection direction, and optionally featuring extension portions, grooves, or through holes to enhance bonding strength and alignment, while maintaining a thin and cost-effective structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a thin plastic substrate is used for flexible substrate, then flexibility and cost are improved, but bonding precision and contact effect deteriorate due to deformation under bonding pressure

Engineering Contradiction:
ImproveflexibilityVSAvoidbonding precision
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The substrate is segmented into a first substrate (thin flexible plastic layer) and a second substrate (rigid support layer), where each layer performs its specialized function - the thin layer provides flexibility while the rigid layer provides dimensional stability for precise bonding

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A composite substrate structure is formed by combining a thin plastic substrate with a rigid support substrate, creating a multi-layer composite that simultaneously exhibits flexibility from the plastic layer and rigidity from the support layer, resolving the contradiction between flexibility and bonding precision

Inventive Principle:
Principle #40Composite materials

2Manufacturing precision

If a rigid carrier is used during bonding process, then bonding precision is improved, but process complexity and risk of bonding bubbles increase

Engineering Contradiction:
Improvebonding precisionVSAvoidprocess complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The rigid support substrate is pre-integrated with the thin plastic substrate before the bonding process, so that the substrate assembly already possesses the necessary rigidity for precise bonding without requiring additional rigid carriers during the bonding operation

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The substrate structure serves its own support function through the integrated rigid support layer, eliminating the need for external rigid carriers or fixtures during bonding, thereby simplifying the overall process

Inventive Principle:
Principle #25Self-service

3Manufacturing precision

If a thicker plastic substrate is used, then bonding precision is improved, but production cost increases and thermal expansion issues occur

Engineering Contradiction:
Improvebonding precisionVSAvoidproduction cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The substrate function is segmented between a thin plastic layer (for flexibility and cost-effectiveness) and a separate rigid support layer (for bonding precision), allowing each component to be optimized independently rather than requiring a uniformly thick substrate

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Rigidity is locally concentrated in the second substrate (rigid support layer) at the bonding region, while the first substrate (thin plastic layer) maintains its flexibility and cost advantages in non-bonding areas, achieving precise bonding without uniformly increasing substrate thickness

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP2993660B1Flexible substrate, display device, and method for bonding electronic device onto flexible substrate
Publication Date: 2020.05.06 BOE TECHNOLOGY GROUP CO LTD
  • EP2993660B1 patent drawingFigure 1a
  • EP2993660B1 patent drawingFigure 1b
  • EP2993660B1 patent drawingFigure 2~3a

AI summary

A flexible substrate, a display device and a method for bonding an electronic device onto a flexible substrate are disclosed. The flexible substrate comprises a base substrate (1), the base substrate (1) comprises a bonding portion (11) for bonding an electronic device and an auxiliary bonding (12, 121, 122) portion integrally formed with the bonding portion (11), the auxiliary bonding portion (12, 121, 122) and the bonding portion (11) are disposed back to back, and the bonding portion (11) completely falls into a region where the auxiliary bonding portion (12, 121, 122) is provided in an orthographic projection direction. With an auxiliary bonding portion (12, 121, 122) being disposed beside the bonding portion (11) for bonding the electronic devices such as ICs and FPCs, when bonding the electronic device onto the bonding portion (11), the auxiliary bonding portion (12, 121, 122) can enhance the strength of the bonding portion (11) and improve the bonding alignment precision and contact property of the electronic device, which further improves the non-defect ratio of the flexible display device and has a lower cost.