COG是chip on glass的缩写，即芯片被直接绑定在玻璃上。这种安装方式可以大大减小LCD模块的体积，且易于大批量生产，适用于消费类电子产品的LCD，如：手机，PAD等便携式产品，这种安装方式，在IC生产商的推动下，将会是今后IC与LCD的主要连接方式。
COG is the abbreviation of the chip on glass, that is, the chip is directly bound to the glass. This installation method can greatly reduce the volume of the LCD module, and easy mass production, suitable for consumer electronic products such as mobile phone, LCD, PAD and other portable products, this type of installation, in promoting the producers of IC, IC and LCD will be the main connection mode.
COG process / process technology
COG制程是利用覆晶（Flip Chip）导通方式，将晶片直接对准玻璃基板上的电极，利用各向异性导电膜（Anisotropic Conductive Film，后面简称ACF）材料作为接合的介面材料，使两种结合物体垂直方向的电极导通。当前COG接合制程的生产作业流程，均以自动化作业方式进行。COG接合作业由各向异性导电膜贴附，FPC预绑定和FPC本绑定三个作业组成
COG process is the use of flip chip (Flip Chip) conduction mode, the direct wafer alignment electrode on the glass substrate, using anisotropic conductive film (Anisotropic Conductive Film, hereinafter referred to as ACF) as material interface bonding materials, two kinds of combination of vertical electric conduction pole. At present, the production process of COG joint process is carried out in automatic operation mode. COG engagement is composed of anisotropic conductive film attached, FPC prebinding and FPC binding three jobs
(1) conductive film attached to an anisotropic conductive film
First of all, the first step in the COG production process is to attach ACF to the LCD electrode part, then tear the ACF release paper, and only ACF is attached to the LCD electrode part to complete the ACF attachment operation.
(two) FPC prebinding
ACF will complete the attached operations LCD IC pre operation to move the binding IC binding pre project, this project will be IC on relative to the LCD electrode, so need to read through the CCD image recognition, computer image processing system, IC and LCD respectively to identify the preset identification position, by a computer automatic calculation of relative coordinates after accurately IC posted on the LCD electrode, the completion of the pre IC binding activity.
(three) FPC bindings
Finally, the IC pre binding operation LCD will be transported to the IC binding engineering for IC binding work. This project is the key to the quality of COG process. Pressing temperature, pressing pressure and pressing time are three elements of ACF curing.
1, pressing temperature: ACF bonding material is mainly polymer resin, which can be mainly divided into two types: Thermosetting (Thermal-Setting) and thermoplastic (Thermal Plastic) resin, and the general ACF manufacturers provide technical data for ACF characteristics. Temperature has the greatest influence on adhesion. Too low temperature can cause resin to dissolve. Too high temperature will cause the loss of conductive particles. Therefore, the temperature must be controlled in the best range to ensure the reliability of products.
2, pressure: the maximum pressure on the resistance effect, too little pressure will cause the contact area between the conductive particles and the electrode is not enough, and the poor conductivity situation, but too much stress will crush the conductive particles reduce the conduction resistance, so the pressing pressure must be controlled to maintain good conductivity in the best range.
3, the pressing time: because the flow characteristics of conductive particles in ACF, pressing time must have pressure temperature collocation, interaction between the two, increase the pressure temperature can shorten the pressing time, reduce the pressure temperature would increase the pressing time, these two parameters will make the Bump capture examples of conductive collocation the number can improve. But the increase in time will reduce the capacity.
To sum up, the most important thing is to establish the binding parameters in IC. The interaction parameters between the three parameters are pressing temperature, pressing pressure and pressing time, which are most important in process quality and productivity.