The Industrial Technology Research Institute (Hsinchu, Taiwan) or ITRI exhibited a modular micro LED display at the just concluded CES 2020. Part of what made this display interesting is the claim by ITRI that it is the “world’s first display fabricated by the use of mass transferred micro LED chips onto Printed Circuit Board (PCB) backplanes without the use of temporary backplanes.”
The device was produced by a team in which ITRI developed the mass transfer technology. PlayNitride Inc. (Zhunan Township, Taiwan) supplied the micro LEDs, Unimicron Corp. (Taoyuan, Taiwan) provided the PCB backplanes and Macroblock, Inc. (Hsinchu, Taiwan) provided the driver ICs and handled display assembly.
The incentive to develop and successfully implement mass transfer of micro LED chips onto PCB backplanes is financial. ITRI explains that this method has the potential to reduce micro LED display production cost by as much as 20% when compared to a conventional process that uses temporary backplanes.
Up to now, implementing a mass transfer approach has proven difficult. Part of the reason is that PCB substrates are typically uneven making it difficult to directly mount the small micro LED chips. Developing a means to address this difficulty was the focus of the ITRI team.
Little detail seems to be publicly available on the technology developed by the team to directly mount LED chips on a PCB board backplane. None-the-less, the result of the effort was a micro LED display module having a PCB substrate that measured 6 cm x 10 cm. Each micro LED display module consisted of 45,000 micro LED chips each sized below 100 microns. The pixel pitch was about 650 microns.
A 5 by 3 array of micro LED modules were then assembled into a larger display. The result was a 30 x 30 cm display having a color pixel resolution of 480 x 480. An extra optical film was added to minimize reflectivity so that the display could present high contrast even when in a bright ambient environment.
A video appended to the end of this article shows the display in operation at the CES exhibition. The figure below is a photo of the display also captured at the CES exhibition.
Modular micro LED display developed by ITRI and shown at the CES exhibition.
Beyond the CES demo, the modules can be assembled into displays of different sizes and shapes. ITRI expects that this will allow fabrication of micro LED display optimized for a variety of niche applications.
Commenting on next steps in the development process, ITRI stated that the organization plans to develop mass transfer of micro LED chips onto glass backplanes during 2020. Such micro LED displays could be used in gaming monitors. ITRI also plans to develop mass transfer of micro LEDs onto Si based backplanes during 2022 – 2023. Such micro LED displays could be used in augmented reality applications.
The institute expressed the desire to expand partnerships through licensing in order to accelerate micro LED development. -Arthur Berman
