MicroLED Transfer (Pick and place) - Page 7

According to reports early in 2020, Samsung Electronics partnered with Epistar and PlayNitride that will enable Samsung to release its first true microLED TVs by the end of 2020. A new report from Korea suggests that Samsung is struggling with technology issues and it is not likely it will meet its goal of a product release in 2020.

The reports suggest that production yields are very low - apparently Epistar is not able to provide Samsung with the millions of microLEDs required to produce its TVs. Another major issues is Samsung's transfer process which is still not accurate enough - with the result being that display assembly yields are painfully low.

Researchers from the University of Waterloo in Canada developed a new transfer and bonding method to deposit a flexible microLED array on plastic substrates.

The technique, referred to as a "paste-and-cut", starts with temporarily bonding the LEDs on a process/handle wafer onto a glass substrate (the paste step). The LEDs are then released (cut) to the flexible substrate. This approach allows the LED to be optimized and then combined with other materials.

USA-based eLux was established in 2016 as a spin-off from Sharp Labs of America, to commercialize a unique MicroLED production technology. The company was in stealth mode for a few years, and is now finally discussing its technology and business. We talked to the company's president and CEO Jong-Jan Lee, who explains the company's technology, status and plans.

eLux's technology is based on a unique approach that moves microLEDs from wafer to the target substrate without the need of a pick-and-place process. The so-called fluidic process uses microLEDs dispersed in liquid and wells built onto the substrate. The microLED dispersion is spread over the substrate and the LEDs simply fall into place - a sort of self-assembly process, which can be seen in the video above.

Canada-based VueReal is a startup company that develop Micro-LED based microdisplays. The company's Continuous Pixelation micro-printing technology offers high density displays, high production yields and a simple design.

VueReal's founder and CEO, Reza Chaji, was kind enough to answer a few questions we had on the company's technology and business.

Reza, thank you for your time. Can you explain VueReal's micro-printing process and technology?

VueReal’s solution is a true printing process where you do not need to pick LEDs for each transfer. It is based on a cartridge design by VueReal that releases the LEDs selectively into the substrate.

Seoul Viosys and Seoul Semiconductors have jointly developed a new MicroLED technology, called Micro Clean LED that basically packages three separate LEDs (red, green and blue) into a single "one-single MicroLED pixel".

The idea is that these packaged colored pixels will be easier to transfer to the target substrate compared to the transfer of three different LEDs. The package itself does not contain any driver ICs.

Taiwan-based microLED developer Mikro Mesa announced that it achieved a breakthrough in its microLED transfer and bond process, which now enables the company to transfer 2-5 um microLED chips using a large 4-inch stamp.

Mikro Mesa's new process can transfer color (RGB) vertically-structured microLED chips and create a full-color display. It can be used to create high-density dipslays - up to 1,800 PPI and be used to create large microLED TVs, over 55-inch in size. The new process is a low temperature one (below 200 degrees Celsius) and can be used on flexible substrates - and be also used to create transparent displays.

AU Optronics president, Paul Peng, says that he expects Micro-LED displays to enter the market within 1-2 years. The first displays will be large-area signage and small-sized VR displays. Micro-LEDs for the automotive market will take longer to commercialize - around 5 years.

AUO recently demonstrated a 12.1" LTPS micro-LED display prototype that features a resolution of 1920x720 (169 PPI). AUO discloses that this display was produced using the company's self-developed transfer process that can move 50,000 - 60,000 LEDs per transfer (AUO did not detail the time it takes to perform a single transfer, though). AUO is now developing repair technology to take care of damaged LEDs.

iBeam Materials announced that it has received an investment from Samsung Ventures. iBeam developed a technology that can be used to produce LED chips on large-area flexible foils.

iBeam Materials, founded in 2011 in the US, is still at an early stage but this technology could enable the production of micro-LED devices directly on large-area flexible substrates without the use of a transfer (pick-and-place) process.

Researchers at Zhejiang University developed a laser-driven programmable non-contact transfer printing technique that could be applicable to the transfer of Micro-LED chips. The researchers used an innovative design based on an active elastomeric micro-structured stamp with tunable adhesion.

The tunable adhesive used in this technique features cavities filled with air and encapsulated by a micro-patterned surface membrane, used in easily available sandpapers. The micro-patterned surface membrane can be inflated dynamically to control the interfacial adhesion by heating the air in cavities.

US-based Rohinni announced that it has received initial orders for its Pixalux mini-LED and micro-LED placement solution. The company expects to ship more systems in the current quarter, and anticipates higher-volume market adoption in 2020.

Rohinni says that its system combines higher throughput and accuracy for small-die applications to provide a compelling and highly-competitive solution.