In the context of the era of full-screen mobile phones, Incell's integrated chip solution with TTDI touch IC and display IC has gradually become the trend of iPhone LCD screens. Among them, incell LCD has two processes, COF and COG, which of these two processes is better to have become a topic of debate.

In the iPhone after-sales market, Incell LCD is still the absolute mainstream, among which LTPS-LCD, or polysilicon LCD screen, is deeply loved by the mobile phone repair market. LTPS-LCD displays represented by iphone6 and 7 mostly use TDDI chip + Incell bonding technology because TDDI integrates touch and display two chips, which has unique advantages such as low cost and less space. In the era of full-screen smartphones, Touch-In-Cell (oncell/incell/TDDI) technology will undoubtedly continue to dominate the mobile phone repair screen market. Because products with external cover touch technology (OGS/G+FF/G+G) cannot meet the design of narrow-side products, they will lose their dominant position in this wave of development opportunities in the high-end market.

Incell LCD display panel needs to be driven by a drive chip (Drive-IC). Driver chip packaging technologies mainly include COG (Chip-on-Glass) and COF (Chip-On-Film). COG is to bond the Driver IC to the glass, and COF is to bond the Driver IC to the FPC.

Incell COG

The COG process is relatively mature and low in cost and can be used to make LCD screen assemblies thin and light. The biggest advantage of COG is that the product quality is stable and the yield is high. COF uses FPC to reduce the width of the frame, so the reserved area of the panel is small, and it is easier to achieve an ultra-narrow frame. However, the COF program also has corresponding difficulties: this program requires an increase in FPC; at the same time, the packaging temperature is high, which places higher requirements on the process; and the cost is currently higher.

Incell COF

The packaging trend of Incell LCD is to replace COG with COF. COF's mainstream packaging technology is a roll-to-roll process, that is, a process technology in which flexible copper clad laminates are manufactured in a continuous manner by rolling into FPC. The advantage lies in: reducing creases or damage caused by frequent manual operations; Multi-processes such as rolling, cleaning, laminating, and winding; greatly improve production efficiency.

The reason why ZY In-cell LCD uses the COF solution is that the full screen needs to minimize the width of the BM area to achieve a narrow frame and increase the screen-to-body ratio. Compared with IC's COG technology on glass, COF technology can reduce the width of the frame by about 1.5mm. And the current COF process is very mature, and the COF incell screen assembly will become the mainstream product in the mobile phone repair industry in the future.