Electronics Board for Flexible Displays

The era of mobile computing devices such as tablets and smartphones has brought with it a variety of new gadgets that allow us to work on the go. It has also ushered in formfitting medical devices that monitor our health and foldable displays that can be used in any orientation. For these new gadgets to be made, manufacturers need a malleable electronics board that can stretch and bend to match the device’s shape. This type of flexible substrate is called a flexible printed circuit board (FPCB).

Traditionally, FPCBs are composed of insulating films such as polyimide and transparent polyester, conductors such as copper or aluminium, and a surface finish such as immersion gold. But the latest advances in flexible display technology are causing manufacturers to look at this technology in a different way.

The idea behind flexible screens is to make a digital display that can be bent to conform to the user’s hand or curved around the edge of a car’s steering wheel. However, to fully realize this potential, the devices need to be flexible in more than just their displays. The electronics board components on a flexible screen need to be able to bend too, and this is where the current limitations on this technology lie.

Flexible Electronics Board for Flexible Displays

Manufacturers have two main types of malleable boards for their devices: flexible and rigid-flex PCBs. The difference is that the flexible variants are essentially flat, while rigid-flex PCBs are thicker and can be made to resemble the shape of the device they are inside.

To meet the demands of flexible displays, engineers have developed flexible substrates for their circuit boards, but the next step is to develop a malleable electronics board that can actually bend and stretch in response to a variety of conditions. This can only be achieved by using a different type of material, and researchers at the UNIST display center are hard at work developing such materials.

Some of the research being carried out by the team involves a flexible active-matrix backplane for OLED displays and EPDs, as well as thin-film PV and sensor arrays. Other work looks at printing and other solution-processing deposition methods for organic semiconductor materials that perform well under bending.

Finally, there is a need for more mechanical tests of the constituent materials in flexible display devices, which cannot be performed under vacuum conditions using SEM and transmission electron microscopy, but instead must use real operating environments with humidity and temperature control. A nano-UTM is being developed that can measure the mechanical properties of these organic materials on a micron scale by imaging gauge sections during tensile tests.

These technologies will be critical for creating devices with flexible displays that can flex locally and orient themselves to the user’s hand, and access a set of unique software commands. This will allow them to be more durable, lighter and thinner than their rigid counterparts. It will also allow them to be dropped without breaking, and folded into different shapes without losing functionality.