“Be in IT.”
The slogan for the CES held in Las Vegas last January was all about the metaverse. Visitors to the exhibition focused on who will be the winner in the competition for extended reality (XR) devices that will bring the metaverse to life.
LG Innotek (CEO Jeong Cheol-dong) announced on February 27 that it had introduced 2Metal Chip on Film(COF), an essential product for XR devices, to strengthen its market targeting. The product attracted visitors’ attention as it was exhibited at LG Innotek’s metaverse zone.
COF is a semiconductor package substrate that connects displays and flexible Printed Circuit Board(PCB)s. It minimizes display bezels of devices such as TVs, notebook PCs, monitors, and smartphones and helps to reduce modules’ form factor. It requires advanced technology because it forms microcircuits on a very thin film. It is also called the ultra-thin flexible PCB (FPCB) that replaces existing FPCB.
2Metal COF technically upgrades conventional single-side COF. While a conventional COF implements circuits on only one side, the biggest advantage of 2Metal COF is that this is super integrated by forming circuits on both sides.
This product finely perforates micro-via holes on a thin film and implements an ultra-micro circuit on both sides, transmitting signals between electronic devices more quickly and enabling ultra-high definition screens.
According to LG Innotek, the via hole size of this product is 25 μm (micrometer). Considering that the thickness of the hair is 100 μm, it makes holes one-quarter as thick as the hair. The smaller via holes create more channels connecting the product's top and bottom and the more pattern circuits that electrical signals can pass through.
As the metaverse era has recently been in full swing, demand for curved or folding displays has increased, and flexibility is also required for the attached components. It is also why 2Metal COF, which can be freely bent, is considered one of the products in line with current trends in the display industry.
■ Supporting high-resolution display... Expected to increase user concentration level
LG Innotek's 2Metal COF can form a total of more than 4,000 circuits (pattern circuits, also called channels, through which a signal passes per display pixel) on a film (1 unit), which is limited space. Generally, more pattern circuits result in enhanced pixels. And XR devices require higher levels of immersion that only enhanced pixels can deliver.
If the resolution of the virtual image displayed through an XR device is low, the users may feel like viewing the image through a mosquito net which is said a screen door effect. LG Innotek has continuously improved the specifications of the 2Metal COF since 2016 to minimize the screen door effect and support the ultra-high resolution.
In particular, LG Innotek applied new engineering technology to reduce the circuit width from 18 to 16 μm pitch, representing the narrowest level in the industry. Since the number of pattern circuits that can fit on the COF surface increases as the circuit width is reduced, users can view images with better quality, even on a display of the same size.
IT manufacturers are increasingly adopting displays with high definition and minimal bezels to enhance the competitiveness of their devices. In the past, manufacturers used chip-on-glass (COG) technology to support display operations. However, as COG places a chip on a display, it does not meet current display industry trends of no bezel and flexible since it cannot support flexibility. It has forced the manufacturers to look for alternative technology that stably supports high pixels while the display’s bezels continued to be reduced, leading to the wide demand for 2Metal COF.
■ Flexibility and unbounded design with thin films
LG Innotek’s 2Metal COF is a thin, flexible film type that can be smoothly folded or rolled. Moreover, it bends more smoothly than conventional single-sided COF. It reduces the required mounting space for the display, and the set makers can secure more space for other parts. It even helps with designing and engineering more advanced XR devices.
LG Innotek applied unique ultra-micro circuit forming technology to double the circuit integration of the 2Metal COF while minimizing the thickness. The product’s film thickness is only 70 μm, the thinnest of semiconductor substrates, and clearly offers many advantages compared to the thickness of 150 μm or more for conventional semiconductor packaging substrates.
Reducing the thickness helps make finished products to be more flexible and slimmer. It can increase design and engineering freedom for display panel manufacturers. It also helps consumers find products with designs that are more complete than conventional XR devices.
■ Opening the era of XR and a wide range of applications with 2Metal COF
LG Innotek is further advancing its technologies and actively carrying out promotional activities in North America and Japan, where many XR device companies are active, to widen the gap with competitors.
The highly integrated circuit implementation technology of 2Metal COF is applied as an alternative technology for products in which FPCBs are not satisfactory and are developed for new product group applications such as micro LEDs.
“We will continue to lead the 2Metal COF market based on the technical capabilities and quality that have led the substrate business for 50 years,” said Son Kil-dong, Senior Vice President of the Substrate & Materials Business. “We will continue to create differentiated customer value with products that can be applied to various applications.”