Processus de production d'affichage à cristaux liquides :
1, LED electronic display chip inspection: Whether there are mechanical damage and pitting on the surface of the material (whether the lockhill chip size and electrode size meet the process requirements and whether the electrode pattern is complete.
2, LED display screen expansion: Since the LED electronic display chips are still arranged tightly after dicing, the spacing is very small (about 0.1mm), which is not conducive to the operation of the subsequent process. We use a film expander to expand the film of the bonding chip, and the distance between the LED chips is stretched to about 0.6mm. Manual expansion can also be used, but it is easy to cause undesirable problems such as chip drop and waste.
LCD
3. LED dispensing: apply silver glue or insulating glue on the corresponding position of the LED display bracket. The difficulty of the process lies in the control of the amount of glue. There are detailed technological requirements for the height of the colloid and the position of the glue. Because silver glue and insulating glue have strict requirements on storage and use, the waking, mixing, and use time of silver glue are matters that must be paid attention to in the process.
4. LED glue preparation: Contrary to glue dispensing, glue preparation is to use a glue preparation machine to apply silver glue on the back electrode of the LED, and then install the LED with silver glue on the back of the LED bracket. The efficiency of glue preparation is much higher than that of glue dispensing, but not all products are suitable for the glue preparation process.
5. Manual LED chip: Place the expanded LED chip on the clamp of the chip table, place the LED bracket under the clamp, and puncture the LED chip to the corresponding position one by one with a needle under the microscope. Compared with automatic rack mounting, manual piercing film has an advantage, it is convenient to change different chips at any time, and it is suitable for products that need to install multiple chips.
6. Montage automatique du grand écran LED : le montage automatique est en fait une combinaison des deux étapes de distribution de colle et de montage de la puce. Tout d'abord, appliquez de la colle isolante sur le support LED, puis utilisez une buse d'aspiration pour aspirer la puce LED depuis la position mobile, puis placez-la. Dans la position de support correspondante. Dans le processus de montage automatique, il est principalement nécessaire de se familiariser avec le fonctionnement et la programmation de l'équipement, et en même temps d'ajuster la colle et la précision d'installation de l'équipement. Dans la sélection des buses, essayez d'utiliser des buses en bakélite pour éviter d'endommager la surface de la puce LED, en particulier la bakélite doit être utilisée pour les puces bleues et vertes. Parce que la buse en acier rayera la couche de diffusion actuelle à la surface de la puce.
7. LED sintering: The purpose of sintering is to solidify the silver paste. The sintering requires temperature monitoring to prevent poor batch performance. The sintering temperature of silver paste is generally controlled at 150 degree , and the sintering time is 2 hours. According to the actual situation, it can be adjusted to 170 degree for 1 hour. Insulating glue is generally 150 degree for 1 hour. The silver glue sintering oven must be opened every 2 hours to replace the sintered product according to the process requirements, and it must not be opened at will. The sintering oven must not be used for other purposes to prevent pollution.
8. LED pressure welding: The purpose of pressure welding is to lead the electrode to the LED chip to complete the connection of the inner and outer leads of the product. The pressure welding process of LED display has two types: gold wire ball bonding and aluminum wire bonding. Press the first point on the electrode of the LED chip, then pull the aluminum wire to the top of the corresponding bracket, press the second point, and then tear the aluminum wire. The gold wire ball bonding process burns a ball before pressing the first point, and the rest of the process is similar. Pressure welding is a key link in the LED large-screen packaging technology. The main things that need to be monitored in the process are the shape of the pressure-welded gold wire, the shape of the solder joint, and the tensile force.
9. LED encapsulant: The encapsulation of LED electronic display mainly includes three types: glue, potting, and molding. Basically, the difficulties of process control are bubbles, lack of material, and black spots. The design is mainly the selection of materials, and the selection of a good combination of epoxy and brackets. 1LED dispensing, TOP-LED and Side-LED are suitable for dispensing packaging. Manual dispensing and packaging requires a high level of operation. The main difficulty is the control of the dispensing volume, because the epoxy will thicken during use.
The dispensing of white light LED still has the problem of phosphor precipitation which causes the color difference of the light; LED encapsulation, Lamp-LED encapsulation adopts the form of potting. The potting process is to first inject liquid epoxy into the LED large screen molding cavity, then insert the pressure-welded LED large screen bracket, put it into the oven to cure the epoxy, and then take the LED out of the mold cavity to form; LED Molded packaging, put the pressure-welded LED large screen bracket into the mold, clamp the upper and lower molds with a hydraulic press and vacuum, put the solid epoxy into the entrance of the injection channel, and press the hydraulic ejector into the mold glue. In the channel, the epoxy follows the glue channel and enters each LED molding groove and cures.
10. LED curing and post-curing: curing refers to the curing of the encapsulated epoxy. The general epoxy curing conditions are at 135 degree for 1 hour. Molded packages are generally at 150 degree for 4 minutes. Post-curing is to fully cure the epoxy while thermally aging the LED. Post-curing is very important to improve the bonding strength between epoxy and PCB. The general condition is 120 degree , 4 hours.
11. LED cutting and dicing: As LED displays are connected together in production, Lamp packaged LEDs use cutting ribs to cut the connecting ribs of the LED bracket. SMD-LED is on a PCB board and requires a dicing machine to complete the separation work.
12. LED test: test the photoelectric parameters of the LED, inspect the appearance size, and at the same time sort the LED electronic display products according to customer requirements.
13, LED electronic display packaging: the finished product is counted and packaged. Super bright LED needs anti-static packaging.
