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[IMID 2017] Opening solution for next generation high-resolution OLED implementation

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Various solutions for high resolution OLED implementation were released at iMiD 2017 held in COEX from October 18th to 19th. As the resolution of small and mid-sized OLEDs, which are currently being commercialized, is staying at the QHD level, the solutions released at this time have attracted a great deal of attention from display members.

First, Hwang Chang-hoon, CEO of OLEDON, who is developing plane source FMM deposition technology, announced at the business forum, “The plane source FMM deposition technology currently being developed is the only alternative for ultra-high resolution OLED manufacturing at 2,250 ppi”. Hwang Chang-hoon CEO said, “We measured the shadow distance using a-step, and it was 0.38 μm. We can fabricate OLED device with 2,250 ppi only if we have this shadow distance.” “We are currently looking for shadow-free process conditions”

<Difference in shadow distance between point source and plane source>

In addition, Hwang Chang-hoon said, “We first co-deposited the host material and the dopant material on the metal plate to evaporate the deposited green donor thin film and measure the green target thin film with the same PL wavelength for the first time” and “Color control of target thin films made with plate sources can be controlled by the amount of dopant molecules in the donor film, so color control is expected to be easy”.

<OLEDON plane evaporation co-deposition material>

AP Systems, which recently announced the successful development of 1,000 ppi FMM using ultra-short pulse laser (USPL), exhibited 5.28 inch FMM of 825 ppi and 4.72 inch FMM of 677 ppi at this exhibition. A company official said, “By developing a burr-free laser process to solve the burr problem caused by the heat generated during the fabrication process, it is possible to fabricate not only FMM of 1170 ppi but also FMM of various shapes”.

<5.28 inch 825ppi FMM of AP Systems>

Finally, Philoptics unveiled FMMs fabricated using electro forming, especially, FMM of 1,200 ppi, which attracted attention this time, was displayed separately in the VIP room. A company official said “We have secured the stability of the process for the production of 1,200 ppi FMM,” and mentioned “We plan to deliver it to panel makers for testing in the first half of next year, and aim to develop FMM at 2,000 ppi later.”

<FMM of Philoptics manufactured by electro forming method>

As such, in this iMiD 2017, various solutions for high-resolution patterning of OLEDs has been released. Recently, as the number of contents requiring high-resolution OLED such as virtual reality contents increases, interest of smartphone users are increasingly interested. It is worth noting which solution will enable the small to medium-sized UHD OLED era.

Is there possibility of High resolution(UHD) OLED Smart-phone generation?

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Recently VR contents experience through smart-phone device has been increased, therefore high resolution of smart phone is becoming necessary. However, OLED smart-phone resolution still remains at QHD level for 3 years since QHD OLED is applied to Galaxy Note 4 for the first time in 2014.

The core point that decides resolution of OLED smart-phone is evaporation process for emission layer. Bottom-up type evaporation method, which is applied to the recent devices is that substrate and FMM (fine metal mask) are horizontally arranged on the upper side of evaporator and vaporize the organic material from the lower linear source in order to form RGB layer.

Thin FMM measures less than 15um thick is necessary for making high resolution OLED like UHD level, however, as FMM gets thinner, it would be difficult to make mass production because technical problems will be occurred such as patterning, sealing and welding.

In order to solve these problems, various metal mask patterning technologies are being developed such as vertical type evaporation and plane source evaporation.

Vertical type evaporator that arranges board and FMM vertical is developed by Hitachi of Japan for the first time. And Canon Tokki exhibited Gen6 vertical type evaporator at Finetech Japan 2013, however it is not being used for mass production at the moment.

<Canon Tokki’s Gen6 vertical type evaporator which is exhibited at Finetech Japan 2013>

According to the recent ETNEWS, Applied Materials developed Gen6 flexible OLED vertical type evaporator and it is being tested in Japan Display.

Plane source evaporator is being tested but also the linear source type. Plane source evaporator method is that an organic material is first evaporated on the metal surface to produce plane source, then re-evaporated in order to form an organic thin film on the substrate.

In the past iMiD 2017, representative of OLEDON, Chang Hoon Hwang mentioned that 2250 ppi resolution OLED can be implemented through plane source evaporator.

For metal mask patterning technology, electro forming and laser patterning technology is highlighted. Electro forming method is developed by Wave Electronics, TGO Technology, Athene and so on. Laser patterning technology is being developed by AP Systems.

As such, development for high resolution OLED is receiving great attention whether it can solve the current problems and contribute to UHD resolution implementation for OLED smart-phone.

<Principle of plane source evaporation developed by OLEDON>

[iMiD 2017] AP Systems, Find FMM answers through USPL

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At iMiD 2017 in BEXCO, Busan on 28th, AP Systems announced that it succeeded in developing 1000ppi FMM with USPL (ultra-short pulse laser).

Since FMM plays a role of depositing pixels and RGB organic materials, FMM serves as a factor that determines resolution and yield of OLED. At present, FMM is mainly manufactured by etching method. This method has a problem that a shadow phenomenon due to the precision, thickness, and weight of the fine pattern occurs, in order to solve this problem, various FMM manufacturing processes such as laser processing and electro-forming have been developed.

Among these, laser processing method has an issue of forming burrs around pin-holes due to the thermal effect caused by laser irradiation. These burrs increase the shadow interval of the FMM, which causes overlapping of patterns during RGB organic deposition, thereby degrading the resolution of the OLED.

AP Systems has developed a burr-free laser process that does not have burr phenomenon and further controls the taper angle.

The Burr-free laser process is a short-time irradiation of unidirectional pulses at a constant number of times, since the laser is not continuously irradiated, it minimizes accumulated heat energy and prevents burr formation. In addition, by controlling energy of the laser, it accumulates energy and forms taper.

In this way, AP Systems explained ‘they produced FMM with various shapes of fine pin-holes such as square, diamond, and polygonal shapes, as well as 1170ppi FMM’, and ‘’We also developed large-area FMM manufacturing equipment with USPL method’.

AP Systems also added ‘multi-beam and USPL is equipped for FMM manufacturing equipment so that it can improve productivity and realize UHD’.

Since the launch of the Galaxy Note4 in 2014, the OLED resolution has remained at the QHD level yet. In order to manufacture an OLED having a high resolution (UHD level or higher), it is necessary to solve various technical problems faced by FMM. Accordingly, it is noteworthy how USPL technology of AP Systems will affect the future OLED market.

<1000ppi FMM produced by AP Systems>

<various type of FMM produced by AP Systems>