What is the difference between COF, COG in Mobile LCD Screen?

Now that the mobile phone has entered the era of full screen, incell's incorporated chip service with TTDI touch IC and screen IC has slowly end up being the pattern of iPhone LCD screens. Among them, incell LCD has two procedures, COF and COG, which of these 2 procedures is better to have actually ended up being a subject of debate.Let’s take a deeper look into what the differences are between COF and COG.
1. What is COF? What is COG?
COG: Chip on Glass, is the most traditional screen packaging technology and the most cost-effective solution, and is widely used. Before entering the era of 18:9 "full screen", the screen of smartphones generally adopted a packaging technology of "COG" (Chip On Glass), that means the IC chip is directly bound to the glass surface of the LCD screen. This packaging technology can greatly reduce the volume of the entire LCD module, with high yield, lower cost and easy mass production. The problem is that glass can't be folded and curled, and with the cables attached to it, it's doomed to have a wider "bottom frame" to match.

The traditional COG technology generally integrates the chip on the glass backplane. Due to the large size of the chip, the frame is still relatively wide, which is mainly reflected at one end of the cable. Xiaomi's MIX adopts the COG packaging process, the reason why the bottom frame is so wide is because many cables are concentrated at the bottom 4 mm. In addition to Xiaomi MIX, LG's G6 and V30 also use COG packaging technology.

COF: Chip on Flex, this packaging technique is to place the screen's IC chip on a flexible FPC and then bend it to the bottom. Compared with the COG solution, the frame can be further reduced and the screen ratio can be increased.

The COF packaging process is a very important packaging technology in the current popular full-screen era, and is generally used in flagship mobile phones, including LCD screens and OLED screens. The reason why Huawei Mate 20 Pro can achieve an ultra-narrow bezel and an ultra-narrow bottom frame, without a bottom frame like the Xiaomi MIX series, is because it adopts the COF packaging process of Synaptics, including ClearView driver IC and ClearPad touch IC. There are still a lot of COF packaging in the industry, Apple iPhone XR, Samsung S9, vivo X21, OPPO R17, Xiaomi MIX 2S, etc., all use COF packaging technology.

2.What is the main difference between COF and COG ?

COF advantage: COF is more about the thickness of the edge and R corner , looks more like original quality.
COF disadvantage: Screen more easy break inside , because the chip is on the flex, and the flex is soft, so easy to broken the screen when doing installation.
COG advantage: The process of production more mature than COF, and the cost also lower than COF technology
So most of the aftermarket screen from market using COG technology.
Less defects rate from installation
battery consumption lower than COF, wont fever.
COG disadvantage: Screen ratio is smaller than COF. The display size of the screen is 0.1 inches smaller than the original, but you can't really tell the difference without looking at it with the eye, or making a special comparison.

Most of the mobile phones nowadays use COF packaging technology instead of traditional COG packaging technology. So that the chip can be placed directly at the bottom of the screen, leaving 1.5 mm more screen space than COG.
We have been committed to providing customers with better quality aftermarket screens, so our SCRS Incell screen for iPhone series also uses COF packaging technology, the width of bottom frame is very close to the original, and the quality is more stable, which has a good common evaluation by our customers.