Applied Chemistry for Engineering (공업화학)

The Korean Society of Industrial and Engineering Chemistry (한국공업화학회)
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Designing an Evaluation Method for the in-situ Impact Strength of Rollable Devices

  • Hyojung Son (Department of Hydrogen and Renewable Energy, Kyungpook National University) ;
  • Ki-Yong Lee (FlexiGO Inc.) ;
  • Byoung-Seong Jeong (Department of Hydrogen and Renewable Energy, Kyungpook National University)
  • Received : 2024.03.17
  • Accepted : 2024.03.25
  • Published : 2024.04.10
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Abstract

In this study, a methodology for evaluating impact strength in rollable devices was developed, focusing on measuring impact strength and evaluating rolling and unrolling durability simultaneously, with findings reported from tests on a real demonstration unit. The study utilized a flexible and rollable polyimide (PI) substrate for the evaluations. The chosen parameters for this methodology were a flat-type impactor, weights of 300 g, 500 g, and 1000 g, a rolling shaft ranging from 30 R to 5 R, and the positioning of the impactor. The results revealed that the difference in defect rates when comparing the 300 g and 500 g weights was minimal. However, the adoption of a 1000 g weight markedly increased the defect count due to damage to the PI film's surface. Furthermore, an uptick in rolling and unrolling cycles led to more pronounced surface scratches on the PI film. These methods and findings are poised to make a substantial contribution towards refining reliability testing for a wide array of rollable device applications, including smartphones, watches, pads, and wearable technology.

Keywords

Acknowledgement

This work was supported by the Industrial Technology Innovation Program funded by the Ministry of Trade, industry & Energy (MOTIE, Korea) [No. 20015778].

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