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Thin Film Deposition Solutions to LED Display Challenges

LED displays in Times Square

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The opto-electronics and display industry is expecting to see significant growth in several LED-driven sectors over the next decade. Precision thin film deposition will play an important role in boosting the performance of the various end-user applications that are being fueled by this growth, particularly LED displays.

Types of LED Displays

LEDs, or light-emitting diodes, are at the core of most modern technologies, and have been present in consumer electronics for years. LEDs are typically used as the backlight to illuminate the pixels in LCD (liquid crystal display) screens in TVs and smartphones, among other devices.

A traditional type of LCD screen is the TFT LCD, or thin film transistor LCD. With TFT, each pixel is divided up into three segments with different color filters: red, blue or green. Changes in the electrical charge applied to the pixel generates a wide variety of colors and brightness across the entire screen.

A newer screen technology, OLED, or organic light-emitting diode, is on the rise. In OLED displays, the pixels illuminate themselves instead of being backlit by LEDs. The electrical current causes each pixel to emit light, which is different from TFT LCD, where the current only changes how the light passes through. This individual control over each pixel often results in better picture quality and energy efficiency for OLED screens. OLED is proving to be a valuable option for smartphones, and rapid adoption of this technology is expected to boost the OLED market to a value of $48.81 billion US by 2023.

Another type of LED that could revolutionize the future of displays: micro-LED. Micro-LED is similar to OLED, but with smaller LED pixels inside the screen, resulting in higher brightness and better efficiency. Between 2019 and 2025, it’s predicted that the micro-LED industry will grow at a staggering CAGR of 80%. The growing demand for wearable technology is a big factor contributing to this expected increase, as is demand for brighter smartphone screens.

Growth in the LED space is particularly relevant in the Asia market, as the boom for consumer electronics continues unabated. There is also increased demand for outdoor LED displays, as live-streaming at concerts, sporting events, speeches and other major happenings becomes more and more prominent – and expected by consumers.

Solving Display Challenges with Thin Film Deposition

To take advantage of the expected growth across the industry, manufacturers targeting LED applications need thin film deposition systems that can deliver precision coatings with consistent, repeatable performance at scale, even when manufacturing large volumes. The added challenge of outdoor screens creates a need for high-quality coatings that protect against – and survive in the face of – unpredictable environmental exposures.

Durable coatings such as diamond-like carbon (DLC) coatings are critical for large outdoor screens as well as smaller devices. DLC coatings help prevent scratches and cracks. Hydrophobic coatings are also needed – they give displays water repellent properties and help reduce smudging from skin oil, a common problem for touchscreen devices. When the soft thin films wear off over time and with use, it makes the displays even more prone to scratching and smudging. To prevent this, LED display manufacturers will need to utilize proven thin film deposition methods and equipment that yield strong, long-lasting coatings.

Thin film deposition technology can also help solve a major manufacturing challenge for micro-LEDs. Interest in micro-LED production is mostly tied to the wearable technology market. Wearable technology will almost certainly be a major market factor in the near future. In 2015, CNBC reported that “wearables will become the world’s best-selling consumer electronics product after smartphones.”

With devices such as the Apple Watch and Fitbit already in high demand and even smarter wearable technology on the way, it’s not hard to see that forecast coming to fruition. Such products are already making waves in fitness, healthcare, and business productivity, and by 2020, it’s estimated that the wearable tech industry will be worth $34 billion.

Micro-LEDs are suited to the smaller screens present in wearable devices, but manufacturability is a problem. Chip bonding is a common manufacturing method used to manually pick and place each pixel, and build an array of LEDs in one screen. However, because each micro-LED pixel is so tiny, this process becomes extremely time-consuming, ultimately raising the cost and slowing time to market.

Micro-LED production is still so new that it’s not clear yet what will work to achieve a lower cost, but a more precise and cost-effective option may be flip-chip technology. In using flip-chip technology, manufacturers could speed the process by bonding an array of pixels at one time, rather than individually. The bonded array would then be transferred to the substrate to create the display. This choice – pick and place vs. flip-chip – presents a key manufacturing decision to be made in the micro-LED space moving forward.

There are a few other considerations for thin film deposition in the micro-LED sector. The flexibility to deposit precision films on small form factors of varying shapes – and to do so consistently and at a low system cost of ownership – will be critical. Because micro-LEDs are much smaller than OLED pixels, using a process that delivers a high yield is also important, especially if micro-LED displays are to overtake TFT LCD and even OLED in smartphones and bigger electronics.