Display Panel Adhesive Interface Tuning Against Lower Film Delamination
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Solution Overview
Problem
Delamination between thin films of a display panel occurs due to expansion of a lower film when a display device is driven, leading to potential corrosion of printed circuit boards due to moisture penetration at the delamination interface.
Innovation Solution
The adhesive strength of the adhesive layer is adjusted to disperse the force caused by the expansion of the lower film, preventing peeling between thin films by ensuring specific adhesive strengths at different interfaces, including the adhesive strength of the first interface to the back side being smaller than the second interface, and the adhesive strength of the fifth interface to the bonding portion being greater than the fourth interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the adhesive strength of the adhesive layer is increased to prevent delamination, then the reliability of the display panel is improved, but the lower film expansion force causes stress concentration and potential damage to the bonding portion
Solution Approach 1:
The adhesive layer is designed with spatially varying adhesive strength: the first adhesive strength in the first region (overlapping the bonding portion) is lower than the second adhesive strength in the second region. This local differentiation allows the adhesive layer to absorb expansion forces in the bonding region while maintaining strong adhesion in non-bonding regions, preventing both delamination and bonding portion damage
Solution Approach 2:
The adhesive strength parameter of the adhesive layer is changed across different regions. By controlling the adhesive strength to be lower in the first region and higher in the second region, the system optimizes the balance between preventing delamination and protecting the bonding portion from stress concentration during lower film expansion
2Ease of manufacture
If uniform adhesive strength is applied across the adhesive layer, then the manufacturing process is simplified, but stress distribution during lower film expansion becomes uneven causing delamination
Solution Approach 1:
Rather than using uniform adhesive strength, the invention applies local quality by differentiating adhesive strength across regions. The first region has lower adhesive strength to accommodate bonding portion movement, while the second region has higher adhesive strength to prevent delamination, optimizing both manufacturing and performance
3Strength
If the adhesive strength at the first interface is increased to match the second interface, then the overall bonding strength is maximized, but moisture penetration and corrosion occur at the bonding portion interface
Solution Approach 1:
The adhesive layer implements local quality with different adhesive strengths in different regions. The lower adhesive strength in the first region over the bonding portion creates a stress-absorbing zone that prevents moisture penetration and corrosion, while the higher adhesive strength in the second region ensures overall bonding integrity
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 effectively prevents peeling between thin films, thereby preventing corrosion of printed circuit boards and moisture penetration, ensuring the display device's operational integrity.
Implementation Method 1
an anisotropic conductive film disposed between the back side and the printed circuit board
Implementation Method 2
an adhesive layer disposed on a second surface opposite the first surface of the back side of the display panel
Data Source
AI summary
A display device includes a display panel including a front side and a back side, a pad portion on a first surface of the back side, a printed circuit board connected to the pad portion, an anisotropic conductive film between the back side and the printed circuit board, an adhesive layer on a second surface opposite the first surface, and a lower film on the adhesive layer. The printed circuit board includes a bonding portion bonded to the pad portion through the anisotropic conductive film, the adhesive layer having a first interface between the adhesive layer and the back side and a second interface between the adhesive layer and the lower film. An adhesive strength of a first portion of the first interface overlapping the bonding portion is from 100 gf/inch to 300 gf/inch, and smaller than an adhesive strength of the second interface to the lower film.