As LED technology develops continuously and LED die-size shrinks gradually, the product application has become more and more diversified. Because of the saturated general lighting market, the display market seems to be the next main battlefield for LED makers. The well-known LED technology for display includes Mini LED backlight unit, Mini LED RGB and Micro LED. This year, most of the LED display makers try to show their advanced technologies by making fine pitch display with Mini RGB LED. At InfoComm 2019 in Orlando, US, most of top companies exhibited large-scale fine pitch display, which draws lots of people and attention.

According to the latest research report of LEDinside, “2019 Global LED Video Wall Market Outlook - Cinema, Rental Market and Price Trend”, as the demand for LED display in the rental market, HDR application, retail and meeting room boosts, the global LED display market scale in 2022 is expected to stand at US$ 9.349 billion.

A fine pitch LED display not only has high resolution but also provides rich detail. All of advantages come from hundreds of thousands of LEDs in the display. Yet the small-sized and dense-packed LEDs also bring the difficulty to the whole supply chain.

In order to understand how LED companies overcome these difficulties and have major breakthrough, LEDinside visited EPISTAR, the leading LED die suppler, and its subsidiary company, Yenrich and had a conversation with Carson Hsieh, VP at EPISTAR Lab and Albert Huang, Sales VP at Yenrich. Hsieh and Huang shared with LEDinside how EPISTAR brings fine pitch displays to another new level with their technology breakthroughs.

(Left: Albert Huang, Sales VP at Yenrich; Right: Carson Hsieh, VP at EPISTAR Lab)

EPISTAR’s Three-pronged Business Integrates Miniaturized LED Technologies

EPISTAR went through restructuring last year and divided into three business entities. The original EPISTAR continues its focus on R&D and production of LED epitaxial wafers and dies, while Unikorn targets III-V semiconductors OEM business. Yenrich, on the other hand, targets innovative LED technologies.

“EPISTAR’s current goal is to develop new technologies to actualize the infinite potential of III-V compound semiconductor!” Hsieh said that EPISTAR sees that LEDs will eventually reach its market saturation in general lighting; therefore, EPISTAR begins to develop its own special RGB package without using the traditional RGB package process. Last year, EPISTAR demonstrated the RGB package with the size smaller than 4mil, which is the smallest RGB LED package in the world.

What’s more, miniaturizing LEDs are the key for fine pitch displays.

Hsieh explained that the ideal fine pitch display should be anti-glare and uniform in appearance while in off-states. And the RGB color should be as identical as possible while in on-states. The key to achieve excellent uniformity lies in the size and shape of the LED package. Moreover, as the LED package decreases drastically, LED makers have to deal with the new challenges, from the very beginning of how to design the proper LED dies all the way to the very end of packaging and testing, in order to maintain the consistency of LEDs,

And it is where EPISTAR can manifest itself in solving all the challenge.

“We used to see things in term of LED itself only, now we need to have more “systematic” thinking.” Hsieh added that, since Mini LEDs and Micro LEDs are still under development, collaborations between the upstream LED die makers and the downstream system makers are critical for better solutions. Otherwise, industry players might see themselves struggling in a situation that the products from LED die makers are not properly designed to fit for the transfer onto the backplane by the system makers. If so, it would be a dead end for LED to be used for this application.

With long years of experience in LED, EPISTAR can deal with difficulties from the epitaxy structure, die design all the way to the backend process. EPISTAR is also very vigorous in developing non-conventional practices that are good for connecting the LED packages with backplane and circuit. EPISTAR seeks to develop turnkey solution not only solving the issue but also integrating the demands from supply chain. Moreover, after the organization being restructuring, EPISTAR will be able to properly allocate the technology and resources from its three business entities, and integrate the technology platforms of each entity to solve the existing issue from the industry.

Yenrich’s Exclusive Fast Transfer Technology Supports Applications of Miniaturization LEDs

Yenrich Technology dedicates itself to innovative technology, specializing LED miniaturization and ultra-fine pitch display technology; therefore, it plays an important role in the new EPISTAR group.

“Yenrich aims to achieve something that can’t be done by traditional technique!” Hsieh pointed out that Yenrich has already developed technologies including miniaturized design, die-transfer, testing and repair that are ready for mass production.

Huang also mentioned that the market shows a trend toward large scale fine pitch display with higher resolution, which can be applied in central control rooms or high-end cinema. And Yenrich, with its core technology, would like to help customers toward this direction.

Yenrich aims to achieve ultra-fine pitch display, with a pitch size smaller than 1.0mm, in order to stand out from the existing mainstream fine pitch display that covers pitch sizes between 1.0mm to 2.5mm. In virtue of the customer, Yenrich demonstrated an ultra-fine pitch display with a pitch size of 0.8mm, by 0404 RGB package and another with 0.6mm pitch size using 4 in 1 RGB package in this year’s InfoComm

As to the applications of end product, Yenrich provides a variety of solutions including POB (package on board) for fine pitch display, COB (chip on board) for advanced fine pitch display and COG (chip on glass) for miniaturized LEDs. Yenrich can always answer customers’ requests with a satisfactory integrated technology.

However, the biggest challenge for LED display makers is how to fast and accurately transfer large amount of miniaturized LED onto backplane; namely, the so-called mass transfer technology. Yet the mass/fast transfer technology is widely recognized by the industry; Yenrich is one of the few companies that provide transfer technology which meets the customers’ requirement.

Furthermore, Yenrich’s SiT bonding technology (Semiconductor Integration Technology) not only transfers the miniaturized LEDs onto circuit board, it also provides the die bonding of miniaturized LEDs through semiconductor process at the same time. In order to further simplify the process and reduce cost, EPISTAR group also developed technologies that are applicable for large COB used for the current mainstream large-sized LCD display.

PN Gap≦30 μm LEDs and Miniaturized LED Transfer Solutions to Debut at Touch Taiwan

EPISTAR group will exhibit its latest developments covering backlight units, miniaturized LED dies and other innovative technologies at Touch Taiwan taking place during August 28 to 30.

Visitors will pay most of their attention to the mass-production-ready miniaturized LED. Compared to previous LEDs with PN gap around 90um, EPISTAR has successfully commercialized Mini LED with PN gap smaller than 30um while Yenrich also provides the bonding technology for them.

At the same time, the ultra-fine pitch displays debuted at InfoComm will be presented the first time in Taiwan as well as the car exterior display by 0404 RGB package. These products are expected to draw attentions from the visitors at Touch Taiwan 2019.

In addition to application products, EPISTAR as well as Yenrich are going to present the exclusive transfer technology, including the aforementioned SiT and the completely integrated LED solutions.

Huang indicated that these new technologies developed by Yenrich are applied in the co-developing projects with the global top-tier companies. These technologies aim to be used for display, backlight unit and more. Yenrich also plans to develop a wide range of new products including those co-developing projects. The EPISTAR group believes that all these upcoming products will show the new paths to the market as well as the customers.