Composition and Structure of LCM Liquid Crystal Display Module
LCM stands for LCD Module, which translates to liquid crystal display module in Chinese The LCD module is simple to say, it is actually a combination of a LCD panel and a backlight source
LCM stands for LCD Module, which translates to liquid crystal display module in Chinese. The LCD module is simple to say, it is actually a combination of a LCD panel and a backlight source. But when it comes to complexity, it is also very complex, with every component and every process being very precise and rigorous. Below, we will introduce the composition, structure, and manufacturing process of LCM LCD display modules from two aspects: Hangzhou IDT Technology Co.,Ltd.
1、 Composition and Structure of LCM Liquid Crystal Display Module
LCM LCD display module is a display module assembled with various electronic components such as LCD panel, backlight, touch module, IC driver, PCB circuit board, etc. The display principle of the LCD module is that the backrest light source component emits uniformly distributed light, which is processed and arranged by the pixels of the LCD panel, and finally presents the image on the screen. The composition structure of LCM LCD display module is very complex, which can be summarized into three parts: LCD panel, module circuit system, and backlight source.
Structural diagram of LCM LCD module
LCD panel: It is the core component of the display module, mainly divided into CF glass substrate, TFT glass substrate, and liquid crystal layer. We can imagine it as a whole structure composed of two pieces of glass with a liquid crystal layer sandwiched in between. The CF glass substrate is on the upper layer, and its structure is mainly composed of RGB color filters, forming the red, blue, and green colors of each pixel. CF glass substrate is a key material for achieving color display of LCD liquid crystal panels. The TFT glass substrate is located in the lower layer and is a substrate glass with signal electrodes, routing electrodes, and thin film transistors. When the current passes through the thin film transistor to generate an electric field change, it will cause the liquid crystal molecules sandwiched between the upper and lower glass layers to deflect, thereby changing the polarization of the backlight source light. The brightness relationship of each pixel is achieved through the outermost polarizer. From this, it can be seen that the LCD panel presents the brightness and color relationship of the image through the cooperation of CF substrate, TFT substrate, liquid crystal layer, and polarizer.
Module circuit system: mainly composed of driver IC and FPC flexible printed circuit board. The driver IC can be understood as the driving chip of the display screen, mainly responsible for controlling the driving current of the display screen. The driver IC is fixed on the lower layer TFT glass of the LCD panel through packaging. Usually, small and medium-sized LCD screens use COG packaging, which means that the driver IC is pressed onto the TFT glass in the form of a bare chip. FPC flexible printed circuit board is a reliable and bendable flexible circuit board made of polyimide material. It is the link bridge between the LCD panel, driver IC, and external PCB substrate. FPC flexible circuit board has a small volume, good heat dissipation, and can be freely bent and folded. It can be arranged according to the required position, thereby integrating various electrical components.
Backlight source: The LCM LCD module itself does not emit light and requires backlight to provide a light source. The light source penetrates the CF substrate to produce color, which is then projected onto the polarizer to produce polarization direction. The image is generated by the different intensity of the transmitted light from each pixel. A good backlight source can provide uniform light, making the display effect of TFT LCD liquid crystal display modules more uniform and delicate. The structure of backlight sources is divided into two types: side lit backlight structure and direct lit backlight structure.
2、 The manufacturing process of LCM LCD display module
The production process of LCM LCD display modules is very precise and rigorous, and every step requires meticulous attention to detail. Below, Hangzhou IDT DISPLAY Technology will provide a more intuitive introduction to the production process of LCD modules. POG production process: cutting and testing of liquid crystal substrates. Firstly, our LCD panels come in full boards, so the first step is to cut the glass substrate according to the product size. Clean, dry, and conduct electrical testing on the small pieces of glass after cutting. The second step is to carry out the bonding work of the polarizer. Before officially bonding the polarizer, a glass grinding and washing process will be carried out, which will greatly improve the yield of the patch. After the bonding is completed, there will be a POG defoaming process to allow the polarizer to better adhere to both sides of the glass and eliminate any bubbles during the surface mounting process. The final step of POG electrical testing is the inspection and acceptance of the entire LCD substrate manufacturing process.
FOG production process: It is a core process in the entire LCM production process, which can be summarized as IC and FPC bonding of LCD panels. First, place the LCD glass substrate that passed the previous step test on the production line, and then perform plasma cleaning on the bonding position to ensure that the subsequent steps are dust-free. The next key steps are ACF attachment, as well as IC bonding and FPC bonding. Further explanation of the principle of bonding is needed here. The academic name of ACF is anisotropic conductive film. It is actually a mixture of conductive particles and resin material. ACF bonding technology utilizes ACF conductive adhesive hot pressing to precisely and firmly bond the driver IC and FPC flexible circuit board onto a liquid crystal glass substrate. ACF technology enables reliable electrical connections, enabling driver ICs FPC、 Effective electrical pathways are formed between LCD panels. It also provides a mechanically reliable connection between the three. The next step is AOI particle detection, which uses optical detection equipment to inspect the bonded LCD panel, checking whether there is any cracking after IC pressing, whether the conductive particles of CF are effectively blasted and the quantity is sufficient, whether there are foreign objects inside the conductive adhesive, whether there are scratches on FPC, electronic component displacement, and so on. After passing the inspection, the LCD panel will undergo a power on test. Finally, perform adhesive treatment on the FPC.
LCM production process: The final step of backlight assembly is carried out on the LCD panel to achieve the process of lighting up. Firstly, the LCD panels that passed the previous inspection are automatically dried to ensure that all the glue has solidified. The next step is to assemble the backlight module, which will not be further introduced here. If there is a demand for resistive touch products, the assembly of resistive screens will be carried out. The next step is to perform automatic welding on the parts that need to be welded, and then use automated equipment to apply machine stickers that are easy to tear, as well as adhesive backing, electromagnetic film, foam adhesive and other auxiliary materials. The final stage is the testing phase, which will involve two tests. The first is the full QC inspection, including electrical testing and visual inspection. Subsequently, another FQC final inspection is required, which is the final inspection before the product is shipped. The qualified product is the final LCM LCD module finished product. Finally, coding and model information will be printed on the back of the product to facilitate after-sales traceability of the product's materials and production status. Of course, before shipment, we also need to conduct sample aging tests on the products to prevent unqualified products from entering the market.
That's all for the introduction of the composition structure and manufacturing process of LCM LCD display modules. Do you have a preliminary understanding of LCM LCD display modules? Hope it's helpful to you.
