Frit Sealing of OLED Displays
Display technologies continue to advance in providing better image quality and user experience. One of the recent advancements in application is the adoption of the organic-LED display (OLED) in consumer electronics devices such as smartphones and large screen TVs. While offering many advantages over LCD such as thinner and lighter panel, wider viewing angle, and enabling lower power consumption, the OLED panel requires advancement in manufacturing processes including a hermetic sealing solution to protect the organic molecules.
Corning developed hermetic frit-sealing solution more than 15 years ago, combining its knowledge of materials, namely frit and glass, with optics, namely the use of a near-IR laser, to locally seal the encapsulation glass to the OLED back plane. In this chapter, we outline the development of optimized frit material to deliver attributes such as hermeticity and required lifetime while enabling the manufacturing process of sealing. Optimization of (localized) laser sealing technology, a critical element to enable OLED panel sealing, is briefly discussed as an example.
A variety of mechanical testing methods to evaluate OLED panels are discussed, ranging from component level testing such as the anticlastic bending test and four-point bend tests to simulated tumble testing of devices. It is critical and important for engineers and scientists working with OLED panels and their evaluation to complement mechanical testing with failure analysis of the panel/device after testing. Failure analysis provides important information to discern the root cause and mode of failure, which should be relevant to replicate the intended failure modes in manufacturing processes and/or in field (use case). Mechanical testing and failure analysis become increasingly more critical as panel thicknesses are continually decreased. Each test method and its challenges for implementation are discussed, in the perspective of ensuring the associated failure modes/causes are well understood. After executing many tests over years of development and rigorous analyses, we strongly recommend the adoption of anticlastic bending test in addition to the more standard mechanical tests when assessing the mechanical integrity of OLED panel.
KeywordsFrits Frit-sealing Laser-sealing Durability Sintering Mechanical testing Failure mode analysis Anticlastic Four-point bend
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