Roll‐to‐roll coating of flexible glass

Abstract

Flexible glass is a relatively new kind of substrate with a unique combination of properties that are, in different aspects, ideal for numerous applications. The material has aroused significant interest and has prompted activities in R&D communities dedicated to topics such as flexible electronics, flexible OLED and flexible PV. As a result, device demonstrators of considerable maturity have been created, some of which were even manufactured using a roll‐to‐roll (R2R) process. So far, these activities have not resulted in marketable final products that are produced in an industrial context.The key prerequisite for a widespread industrial adoption of R2R processing of flexible glass substrates is the availability of suitable and proven manufacturing equipment. The tools need to be able to handle and process this delicate material, taking into account its mechanical properties, which differ significantly from the typical flexible substrates such as paper, polymer film, or metal foil.This article discusses specific equipment aspects that need to be considered in the R2R handling of flexible glass, both in general and by taking the example of a roll‐to‐roll lab coating system. This tool has been designed specifically for handling flexible glass and will be available to the interested community from October 2016.Furthermore, it is shown how different processes such as R2R sputtering, evaporation, and flash lamp annealing can be used for potential flexible glass applications in flexible electronics, architecture, and energy conversion devices. Beyond that, related layer stacks deposited by vacuum coating will be discussed.

Roll‐to‐Roll Fabrication of Solution Processed Electronics

“…For R2R processing to be applicable, the used substrates obviously need to display a certain degree of mechanical flexibility. Several types of substrate materials have been reported for use in R2R manufacturing, the most important ones being thin glass, polymer films, and metal foils or metallized polymer films . For certain applications, also paper substrates have been used .…”

“…Thinner glass is preferred in this respect to thicker glass, as the stresses building up during bending increase with substrate thickness. The peculiarities in handling thin glass in a R2R setup compared to non‐breakable substrates are described by Deus et al Metal foils display barrier properties comparable to those of thin glass and are also very stable against stretching under stress, but require very careful web handling, as they tend to wrinkle irreparably, which can lead to serious problems for device performance. Due to their porosity, paper substrates are not suited for printed electronic applications which require the strict exclusion of moisture or oxygen but can be employed when only environmentally stable materials are used, for example, in the case of smart cards.…”

Flexible and wearable acoustic wave technologies

“…Within this thickness range, the glass exhibits good bendability and flexibility similar to those of plastics or metal foil substrates. 39 Flexible glass retains all the advantages of the bulk glass, e.g., an large optical transmittance (larger than 90% in visible light), a low stress birefringence, a smooth surface with a good temperature tolerance (up to 600 C), a root mean square (RMS) roughness of 1 nm or less, a low coefficient of thermal expansion (CTE, 410 -6 /°C), a high dimensional stability, a good resistance to chemical processes, a good scratch resistance and electrical insulation, and a good impermeability against oxygen and water. Chen et al fabricated flexible/transparent ZnO thin film SAW devices on ultrathin flexible glass substrates.…”