MicroLED Transfer (Pick and place) - Page 8

Digitimes reports that PlayNitride raised $50 million and is ready to start trial production of micro-LED chips by the end of August 2019. PlayNitride will increase its headcount by 100 employees.

PlayNitride told Digitimes that it achieved a yield rate of 99.9% in its LED transfer (pick-and-place) process. Using mass repair technologies, the company is certain it can achieve commercial viability of its process. The company's mass transfer speed is 10,000 chips per second. This means that for a Full-HD (1920x1080) display it will take just over 10 minutes to transfer the LED chips. A 4K display will take just over 40 minutes.

PlayNitride demonstrated its latest Micro-LED displays at SID DisplayWeek 2019, and the following recently-published video shows the company's booth and prototypes:

So first up we have a 7.56" 720x480 (114 PPI) transparent MicroLED display, which looks very impressive. This is the same Micro-LED display that TianMa demonstrated at its own booth. Interestingly, under direct light from it seems that the display is made from tiles - but PlayNitride says that the squares are made from the stamping process, and the company is developing technology that will remove these marks.

TCL subsidiary China Star (CSoT) demonstrated a 3.3" 232x116 transparent Micro-LED prototype display. The display is built on an Oxide-TFT (IGZO) backplane - CSoT says that this is the first such display ever demonstrated. The transparency is around 45%.

CSoT says that it developed the display in collaboration with PlayNitride that provided the transfer technology for CSoT.

US and Sweden based Micro-LED developer Glo has partnered with Japan-based display maker Kyocera to demonstrate a 1.8" Micro-LED display that features a resolution of 256x256 (200 PPI). For this demonstration panel, Kyocera provided the LTPS backplane and driving technology while glo provided its InGaN RGB micro-LEDs and its transfer technology.

Glo says its micro-LED technology enables the production of displays ranging from micro-displays to smartphone-sized panels, and have demonstrated several such panels at SID DisplayWeek 2019.

In November 2017 we reported that Taiwan's Electronic and Optoelectronic System Research Laboratories (EOSRL, part of ITRI) has launched a project that brings together PlayNitride, LED driver IC designer Macroblock and PCB maker Unimicron with an aim to develop production technologies for high-density Micro-LED displays.

Digitimes today reports that EOSRL has achieved a breakthrough in its mass transfer technology, and is now able to transfer 10,000 micro-LED chips from an sapphire-based epitaxial wafer onto a substrate within an hour. EOSRL demonstrated the process with PCB, Polyimide and glass substrates. Trial production runs will commence in Q4 2019.

US-based VerLASE Technologies announced that it is developing technologies for massively parallel assembly of microLED dies or films. The company has already files for multiple patents for its new technology.

VerLASE says that it is using practical methods and well-proven semiconductor and MEMs industry methods and existing tools. The company's technology will enable "deterministic, massively parallel transfers of microdie, with provisions that allow selective repair". The methods involve techniques used daily in Ink-Jet Printing but is not printing per se.

US and Sweden based Glo has been developing Micro-LED displays on both LTPS and CMOS (microdisplay) backplanes for many years. The company has been rather quiet until now (even though the 2017 investment from Google created some buzz).

Glo has now started to disclose its technology and achievements. At CES 2019, Glo demonstrated two displays. First up is the 1.5-inch smartphone type display you can see in the image above. The 264 PPI 120Hz display is produced on a LTPS backplane and produces 4,000 nits brightness - you can see how it is much brighter compared to the LGD OLED in the Apple Watch next to it (1,000 nits max).

Fuji Chimera Research Institute says that the global microdisplay market reached $161 million in 2018, led by LCoS panels (59.7%) and OLED panels (27.8%).

While some analysts expect Micro-LED to take over the AR microdisplay market, Fuji Chimera says that the technology is not mature enough and there are some technology challenges to overcome still - including those in epitaxial wafer process, mass transfer, defect detection and current drive.

Laser equipment maker Coherent says that its customer have expressed a "reasonable amount of interest " in its Micro-LED solutions. The company is taking orders for R&D tools, but it says that mass production of Micro-LED displays is "still years away".

Coherent offers several laser-based tools used to produce Micro-LED displays, including Laser Lift-Off equipment (LLO) used to separate micro-LEDs from the sapphire wafer and Laser Induced Forward Transfer (LIFT) used to move micro-LEDs from the donor to substrate.

At the Touch Taiwan 2018 trade show, LED developer Lextar Electronics introduced its first micro-LED chips. The company unveiled two technologies - RGB chips and color conversaion chips - with both chips meeting the requirements of mass transfer processes.

Lextar micro-LEDs can be scaled down to 20 um - and feature a luminous efficiency of over 30%.