With the plastics industry taking so much heat, it's not surprising that we’re hearing more about going back to the future with glass. A recent report from IDTechEx Research (Boston), Barrier Films and Thin Film Encapsulation for Flexible and/or Organic Electronics 2019-2029, asserts that the benefits of glass are equal to or exceed plastic in a number of areas: It’s an excellent barrier, features dimensional stability, and is smoother and more transparent than thin plastic films. It does have one big shortcoming, however—in its traditional form, it’s rigid.
This limitation has created space and need for flexible alternatives. For more than a decade, companies and research institutes have been developing flexible, transparent and high-performance barriers, but these approaches are mainly based on some variation of the multi-dyad principle, where multiple alternative pairs of organic-inorganic layers are deposited.
The first flexible glass targeting the display industry was demonstrated about a decade ago.
Flexible glass is essentially thin glass, often thinner than 100 microns, which adds flexibility to the attributes of traditional rigid glass. Getting there involves some challenges, however.
First, glass is not as flexible as plastic. The probability of failure increases with even a moderate bending radius. Furthermore, glass is difficult to handle, because a crack on the sides could easily propagate throughout, causing it to shatter. This was a major issue in vacuum systems, since they would need to be shut down, flushed and cleaned.
Progress has been steady, notes the report. Bendability has significantly improved, largely thanks to a combination of embedding ions and chemically cleaning the edges and surfaces. The former builds in compressive stress near the surface to impede the propagation of edge cracks. The latter removes, as much as possible, sites or microcracks that could act as crack initiation sites. Today, highly bendable phones are demonstrated at shows around the world with flexible glass.
|Market forecast for various technologies through 2028 from IDTechEx.|
Handling, too, has improved. Edge tape added to flexible glass rolls prevent them from coming into direct contact with the equipment. Today, there are also good laser cutting processes that enable singulation without inducing stress or cracks.