46‐1: Invited Paper: High Impact Resistance Out‐Fold Touch AMOLED Display Module

Abstract

Out-fold AMOLED display is requested higher panel hardness and impact resistance than in-fold AMOLED display. The high mechanical strength technology was integrated in 7.1 inch foldable AMOLED display module. A 3mm bending radius outfold touch AMOLED prototype with hardness 7H plastic window is demonstrated. This prototype can pass the ball drop impact test of 135g weight from a height of 35cm.

Fabrication of Ultralarge Curvature Folding-Resistant Polyimide Films by Widening the Elastic Range and Intermolecular Slippery Spacing

“…As the elastic range and intermolecular slippery spacing of PICu films were significantly widened by the point-to-face multi-coordination structure, the static folding resistance of PI films was measured according to Figure a. , As shown in Figure a, the PI films were folded 180° between two flats with a certain spacing (folding radius). Then, the folded PI films were kept at 80 °C for 1 h to accelerate the accumulation of plastic deformation.…”

“…With the electrons advanced toward flexible, wearable, and lightweight characteristics, polyimide (PI) substrates, which were rollable, wearable, stretchable, heat-resistant, and tolerating at least 200,000 times of cyclic folding, started to attract increased attention. − However, as shown in Scheme , the flexible substrate in foldable electrons suffered repeated compressive and tensile stress (σ xx ) and bending moment ( M Z ) on the inner side, outer side, and direction perpendicular to the cross section of the bending area during folding. − Thus, irreversible strain accumulated in the substrate films during folding, which finally led to formation of visible creases, affecting the reliability of the flexible electrons …”

66‐3: Effective Foldable AMOLED Structure with Bendability and Impact Resistance

“…However, this approach induces low impact resistance because softer OCAs tend to cause stress concentration if foldable OLED modules are subjected to a point impact like a ball drop. To prevent ball drop impact damage, stress distribution is necessary and a damping structure under an OLED panel is beneficial [7]. In order to change a point impact into a more distributed surface impact, harder and thinner materials like metal film is effective, and therefore some products with metal film as part of the damping structure under the OLED panel are already on the market.…”

Ultralarge Curvature Folding Resistance of Polyimide Films Based on Spring-Like Folding Segments

“…The trend toward the development of more flexible, wearable, and lightweight electronics has fueled increased interest in polyimide (PI) substrates. These substrates possess desirable features such as wearability, processability, heat resistance, and the ability to withstand at least 200000 cycles of folding, making them highly suitable for a broad spectrum of applications. − However, as illustrated in Figure a, the folding process imposes repeated tensile stress (σ) on the outer side of the flexible substrate and compressive stress on the inner side. − The resulting accumulation of irreversible strain in the substrate films can give rise to visible creases, compromising the dependability of flexible electronics …”

“…In light of the significant widening of the elastic deformation range of PI films by the addition of ADA, we sought to investigate the impact of this copolymer component on the folding resistance of PI films, as demonstrated in Figure a,b. , In static testing, the PI films were folded 180° between two flats with 1 mm (folding radius = 0.5 mm), followed by exposure to 80 °C for 1 h to accelerate the accumulation of plastic deformation. After cooling down, the folded PI films were unloaded, and the spread angle (γ) was measured to evaluate the static folding resistance.…”