Flex Connections: Four Lessons in Engineering Judgment for PCB Designers
Flexible Thinking: ‘Let There Be Light’–Emitting Diodes!
Target Condition: Flex and Rigid-flex Solutions in A&D Display Electronics
Whatever technology is used, there are many individual components crammed into a relatively small space. Many smartphone displays contain more than three million subpixels, for example. Bending these components introduces strain, which can tear electrical connections and peel apart layers. Current displays use a rigid piece of glass, to keep the display safe from the mechanical strains of the outside world. Something that, by design, is not an option in flexible displays.
Organic semiconductors – the chemicals that directly produce light in OLED displays – have the additional problem of being highly sensitive to both water vapour and oxygen, gases that can pass relatively easily through thin plastic films. This can result in faded and dead pixels, leaving a less than desirable-looking result.
There’s also the challenge of the large-scale manufacturing of these circuits. Plastics can be tricky materials to work with. They often swell and shrink in response to water and heat, and it can be difficult to persuade materials to bond to it. In a manufacturing environment, where precise alignment and high temperature processing are critical, this can cause major issues.
Finally, it’s not just flexible displays that need to be developed. The components needed to power and operate the display also need to be incorporated into any overall design, placing constraints on the kinds of shape and size currently achievable.
What next?
Scientists in Japan have demonstrated how to make electrical circuits on plastic thinner than the width of human hair in an attempt to reduce the impact of bending on circuit performance. And research into flexible batteries has started to become more prevalent, too.
Developing solutions to these problems is part of a broader area of active research, as the science and technology underlying flexible displays is also applicable to many other fields, such as biomedical devices and solar energy. While the challenges remain, the technology edges closer to the point where devices such as flexible displays will become ubiquitous in our everyday lives.
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