EHD printing technology helps OLED panel production yield increase to 100%
- Jan 22, 2019 -

Cui Jinxian, a professor at Jeju University in South Korea, and Pems announced the successful development of a 3 micron (μm) panel electrode repair technology using electro-hydraulic (EHD) printing technology, which is expected to increase the production yield of OLED panels to 100%. .

According to ETNews, Jeju University professor Cui Jinxian's research team (AMM Lab) and Pems have announced the successful development of panel electrode repair technology with a width of 3 microns using electro-hydraulic (EHD) printing technology. This technology can increase the yield of OLED displays to 100%.

Cui Jinxian said that the yield of OLED panels is now up to 70%, and the technology developed by the team can be used to repair the remaining 30% of the products, which is equivalent to the OLED panel production yield can be increased to 100%.

EHD printing is a kind of inkjet printing, which belongs to nano and micro-scale graphic printing technology. It is more conducive to the appearance of fine line patterns than conventional inkjet, and can use a variety of materials in the polymer series, which is not limited by the limitations of both quantitative discharge and micro-patterning techniques.

The electrode repair stage in the panel process is a technique of reconnecting the broken electrode patterns. Since the defective portion of the electrode pattern can be locally repaired, it is a highly value-added technology for producing panels. In particular, the panel industry has been very distressed by the low electrode pattern yield of large-size and high-performance panels of 40 inches or more. The development of this new technology is good news.

Two panel fields, TFT liquid crystal displays (LCDs), and OLEDs must be repaired. The TFTLCD panel performs pattern detection and poor pattern repair in the final stages of the TFT array process, the color filter process, and the Cell process.

The OLED panel is repaired during the Cell phase and the module stage where the part has been assembled. In the case where the panel size is less than 5 ,, the module with low yield is directly discarded, which is lower than the cost of repair. However, for panels above 5 inches, repairs are more cost-effective than disposal, and the need for repairs is higher.

OLED panels must use micro-electrodes with a width of 5 microns or less that are invisible to the naked eye. Therefore, the 3 micron electrode repair technology jointly developed by Jeju University and Pems is expected to be applied to the OLED panel process in the future.

Cui Jinxian said that the use of non-contact printing processes to repair electrodes with a width of 3 microns or less is the first in South Korea and around the world. In addition to the construction of printing equipment in a constant temperature and pressure environment, the initial investment cost is also low, and no harmful substances are produced before and after the process, so it is also a green process technology.

This technology was developed by the 2014 Technology Support Business Grant, headed by the Korea Ministry of Industry, Trade and Industry, and will be commercialized by Pems.