Flexible metallic glass substrate with high resilience, manufacturing method thereof, and electronic device using same

Abstract

Disclosed herein is a flexible substrate, made of metallic glass that is of high resilience suitable for use in electronic devices. The metallic glass is composed of a commercial alloy that can be produced in a continuous process on a mass scale, and may be selected from among Mg-, Ca-, Al-, Ti-, Zr-, Hf-, Fe-, Co-, Ni-, and Cu-based metallic glass. Preferably, its crystallization temperature, which determines the process allowable temperature, is 200° C. or higher. The flexible metallic glass substrate exhibits excellent fatigue properties as well as resilience of 1.5 MJ/m³ or higher. Its coefficient of thermal expansion is within a small range of 1 to 20 ppm/° C., so that the flexible metallic glass substrate shows a better interfacial property with electronic devices.

Description

CROSS-REFERENCES TO RELATED APPLICATION[0001]The present application claims priority of Korean Patent Application No. 10-2014-0107023, filed on Aug. 18, 2014, which is incorporated herein by reference in its entirety.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a flexible substrate, a manufacturing method thereof, and an electronic device using the same. Particularly, the present invention relates to flexible metallic glass substrate that exhibits excellent fatigue properties as well as high resilience and process allowable temperature.[0004]2. Description of the Related Art[0005]In recent years, intensive efforts have been directed toward the use of flexible substrates in electronics and electronic devices. Advantageously, the application of flexible substrates makes it possible to perform processes continuously, as in a roll-to-roll process, instead of conventional discontinuous processes. Further, with the growth of demand for f...

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Benefits of technology

[0024]The formation of metallic glass ribbons may include a process of preparing metallic glass into a wide ribbon by controlling a melt spinneret nozzle, and a winding process, after which the resulting product is applicable to a roll-to-roll process and easy to carry and store.

Problems solved by technology

On the other hand, polymers are low in phase transition temperature, such as melting point (Tm) and glass transition temperature (Tg), limiting the temperatures available for processes of fabricating electronic devices to within 100 to 300° C. Further, since polymers are generally vulnerable to oxygen and water, an additional waterproof layer is required in order to ensure the durability of electronics.

Crystalline metal plates manufactured by rolling, for example, have rolling marks thereon, and cannot avoid defects causative of surface roughness, such as grain boundaries, due to the properties of the crystalline materials themselves.

Accordingly, it is difficult to achieve fine surface roughness on a metal film because surface roughness varies depending on the deposition method and conditions.

Moreover, because of its low elastic limit of 0.5% or less, crystalline metal foil is apt to undergo plastic deformation even under small bending and thus to have surface defects such as wrinkles, which further deteriorate the surface roughness.

However, the presence of defects on the crystalline substrate requires the formation of a relatively thick polymer layer.

In addition, the metal substrate retains the intrinsic problem whereby the metal substrate readily allows the occurrence of surface defects thereon because, whether coated with the polymer layer or not, it undergoes plastic deformation even when only slightly bent due to its low elastic limit of 0.5% or less.

Alternatively, other efforts including polishing and alternative processing have been made with the goal of planarizing the surfaces of crystalline metal substrates, but in spite of all attempts, the physical limits of crystalline materials have not yet permitted results of a satisfactory level.

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