Analysis of dotted coating process of dispensing machine

Analysis of dot coating process of dispensing machine when we choose the precision valve Shenzhen XJNJI Intelligence Device Co., Ltd has a certain popularity, has a certain reputation, the new technical intelligent equipment is your no regret choice. Coating process is also a technical work, we often encounter this and other problems in the process of coating. The dispensing process of the dispensing machine is varied, the commonly used way is offset printing and dot coating: dot coating process. The so-called point coating process is to apply the patch to the designated area of the PCB through the dispensing machine. Pressure and time are important parameters of point coating, they control the size and tail of glue point. The tail also changes with the stickiness of the adhesive, changing the pressure can change the size of the glue. The “tail” of the patch adhesive extends beyond the base surface of the component to the next position, and the patch glue is covered on the circuit board pad, which can lead to poor welding. The “tail” of the patch adhesive will extend beyond the base surface of the component and be extended to the next part. The tail-dragging phenomenon can be reduced by making certain adjustments to the dispensing system. For example, reducing the distance between the circuit board and the nozzle, adopting a larger nozzle diameter and lower air pressure will help reduce wire attachment. If the dispensing is pressurized (this is a common case), any change in viscosity and limiting velocity will cause the pressure to decrease, resulting in a decrease in the flow rate, thereby changing the size of the glue spot. Offset printing process. The so-called offset printing is the screen printing process will be the patch offset to the PCB designated area. Although offset printing process and dispensing process are similar, but belong to two different production processes. Compared with the latter, offset printing process has the following characteristics: 1 can be very stable to control the amount of offset. For PCB plates with pad spacing as small as 127 ~ 254 μ m, offset printing process can easily and stably control the thickness of printing adhesive in the range of 50 μ m ±0.2 μ m. Offset printing of different sizes and shapes can be achieved on the same piece of PCB through a single printing stroke. The time required for offset printing is only related to the PCB width and offset speed, but not to the number of PCB plates. The dispensing machine is to place glue on PCB board in order, and the time required for dispensing varies with the number of glue spots. The more glue points, the longer it takes. Leakage is another common problem in patch coating, which may be caused by nozzle obstruction, nozzle tip wear and unevenness of the circuit board. If the patch glue is used for a long time (from a few hours to a few days, depending on the adhesive). The nozzles are usually blocked. To avoid blocking the nozzle, clean it after each use and use a wire to connect the tip of the nozzle. In addition, a large degree of viscosity may also cause leakage. Most customers who use offset printing technology are often very experienced in solder paste printing technology. The determination of the technological parameters of offset printing technology can take the technological parameters of tin paste printing technology as the reference point. If you need more information about new technology intelligence, welcome to hong@xji-china.com


Post time: Apr-24-2019