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The inner workings of a flexible screen

Flexible screens that the consumer can fold or roll were once a complex novelty. Now, they are becoming increasingly more commonplace.

More and more phones and electronic devices are offering flexible screens. Only recently were the newest Samsung Galaxy phones released with folding screens. Oppo, LG and other providers are also beginning to offer flexible screens for their devices.

The first phones with curved displays were produced in 2014 when plastic joined glass as a screen substrate option. The flexible plastic could be bent without breaking, and was much more durable than a thin fragile sheet of glass.

Any kind of screen needs to be durable, but the necessity is increased when flexibility and folding is considered. The other layers of the device have to be just as flexible and durable, which is a factor that has led to a much longer development time.

I don’t believe my eyes!

OLED is currently the display of choice on flexible screens, often being chosen over the LCD alternative. Unlike the backlit LCD screen, the pixels themselves are what emit light in OLED. Thanks to this OLED screens can be much thinner and lighter.

Aside from the cover layer, the glass or plastic layer we interact with, and the OLED, there are two other layers in a flexible touchscreen device:

The substrate layer, which is the bottom layer of the screen, supports the layers that follow. This is usually made of plastic or metal. The most common substrate used for flexible devices is polymide, which has a high mechanical strength and thermal stability. This is also usually used for the cover layer as well.

Powered pixels

The thin film transistor (TFT) layer is between the substrate and the OLED layer. It controls the power delivery to each pixel individually, allowing for high contrast rates and lower power consumption.

Within the TFT layer itself there are also several components that go into its construction. The first layer is glass, metals and polymers and is only microns thick.

Next, there is a gate electrode made of aluminium, gold or chromium. The gate electrode provides a signal to the TFT which begins the contact between the source and drain.

The third layer, an insulator, is used to stop electrical shorting in between the two layers. After that there is another electrode layer and is deposited over the semiconducting surfaces.

Welcome to the fold

As a specialist in day-to-day and obsolete electronic components, Cyclops Electronics can help you source the components you’re looking for. With an extensive stocklist and a dedicated team of account managers, we can guarantee to go above and beyond our competitors. Contact Cyclops today to see what we can do for you on sales@cyclops-electronics.com, or call +44 (0) 1904 415 415.

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Electronic Components

Is it possible to make compostable PCBs?

Decades ago we wouldn’t have thought it possible to create printed circuit boards (PCBs). Now, in 2023, we’re discussing the possibility of biodegradable ones.

A research group from the Johannes Kepler University in Austria developed the biodegradable base for the PCBs. The mix consists of beech wood shavings, organise full-grain spelt flour, fine plaster (CaSO4) dust and beech wood-based inoculum.

After storing the mixture in a flat plastic box in a cupboard for a few weeks a tissue grew. The fungal fibres, called mycelium, formed a kind of soft white skin, similar to paper.

A layer of copper or gold is then vapour-deposited onto the mycelium ‘skin’. Then, a laser will cut away the metal where it’s not needed.

A ‘grow-your-own’ circuit

Storing something in a cupboard for a few weeks has significantly lower production costs than regular PCBs. It also bypasses the need for chemicals and minerals that are hazardous to the environment.

With the use of these, too, there is no need to create specialist manufacturing equipment, unlike with biopolymers. They are made from renewable raw materials like starch or milk protein, but have to use an industrial composting plant that operates at a high temperature.

These ‘skins’ can then be mounted with electronic components like a regular PCB.

The mycelium has a very strong structural integrity, while it remains thin and flexible. It has so far been able to withstand about 2,000 bending cycles, it only shows moderate resistance when folded, can insulate electrical currents and can sustain temperatures that reach 250⁰C.

Early days

So far the concept can only be used in simple electronic devices. A multi-layer circuit or more complex electronics are slightly further in the future. Even at this early development stage, though, a prototype has already been attached to a moisture sensor, a Bluetooth chip that sends the sensor signal to a laptop or smartphone, and a special battery.

In the future it is hoped that production of a smoother mycelial skin through a refined formula could increase the possibilities. It could lead to multi-layer PCBs with smaller components.

Once the circuit has been used, it can be unsoldered and put in the compost. The metal used I the conductor paths will be a biproduct left in the soil, but will be nano-particles in unharmful quantities.

Looking for a fun-guy?

Whether you’re ‘growing’ or manufacturing your PCBs, Cyclops has the electronic components for you. We specialise in obsolete, hard-to-find and day-to-day electronic components, and can source components from trusted sources globally. Contact us today to see what Cyclops can do for you on sales@cyclops-electronics.com, or call +44 (0) 1904 415 415.

 

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