Atmospheric atmospheric plasma plasma can be divided into four categories according to the discharge form and structure: (1) Low-current jet plasma (Plasma Jet) that uses metal electrodes to discharge directly, (2) Uses a high-voltage power supply and inserts an insulating plate between the electrodes to stabilize the dielectric barrier discharge of the plasma (Dielectric barrier discharge, hereinafter referred to as DBD), (3) Corona discharge (Corona discharge) using non-uniform electrode structure, (4) High-temperature plasma torch (Plasma torch) using high-current power supply. The following will explain its design structure, characteristics and related applications. 1. Plasma jet A circular tubular metal electrode surrounds the other metal electrode in the center of the tube. One end of the two electrodes is connected to a power supply and one end is grounded. After the tip is discharged, the high-velocity gas flows through the tube to eject the arc to produce stable plasma. Its characteristics are small plasma area, concentrated energy, high processing efficiency, low concentration of ozone produced, and small static accumulation. Its application effect is the best in atmospheric plasma, but it is limited by the small processing area, usually multiple branches can be connected in parallel to form a wide-width processing system, as shown in the figure below. Current applications include: surface modification, photoresist removal, plasma etching, liquid crystal panel chip bonding, tape-and-reel carrier process cleaning, mobile phone assembly and bonding, biomedical material sterilization and coating/printing pretreatment. The common normal piezoelectric plasma can be divided into four categories according to the discharge form and structure. 2. Dielectric barrier discharge (DBD) DBD (dielectric barrier discharge) is a large-area uniform discharge using a dielectric barrier discharge method. At least one layer of dielectric material (quartz or alumina) is added between two electrodes (plate type or cylindrical type), and because of the dielectric The existence of qualitative and can only use AC power supply. At least one electrode of the two electrode plates needs to be covered with an insulating material, but most of the two electrodes are covered with an insulating material, and the potential is high frequency and high voltage. In this way, a periodic filament discharge can be seen between the two electrodes. The filamentary microdischarge is used to activate and decompose the flowing gas. This discharge method combines the advantages of being able to operate under normal pressure and the characteristic that glow discharge can activate and decompose a large amount of gas under low pressure. Many researchers have applied it to ozone generation, coating and waste disposal. However, the disadvantage of this method is that the current of the filamentous micro-discharge is concentrated in some small points, which can easily damage the surface treatment materials on the electrode plate, and the efficiency of the plasma reaction is also low. About 92% of the energy loss in DBD is in the generation of heat. Generally speaking, the dielectric discharge (DBD) is a filamentary discharge (filamentary discharge, silent discharge), which is a non-uniform filamentary plasma that can be discharged in a large area. However, due to the formation of a filamentary discharge, the plasma density is low, and the plasma The removal efficiency is not high. . Due to the high frequency of gas collisions in the atmosphere, the generation and maintenance of plasma is very difficult. Therefore, a specially designed high-voltage/high-frequency power supply and special gas are required. In common applications, the operating frequency is between 1-40kHz, and the peak-to-peak voltage ranges from several thousand volts to 30,000 volts. Pulse-type power supplies are also used, but they are relatively rare in the industry due to their high cost and poor stability. The operating voltage of DBD is very high, usually around 20KV. In this way, filament or glow discharge can be observed between the two electrodes. Dielectric discharge has always been paid attention to. Since the gas temperature of the discharge is close to room temperature, it belongs to the form of cold plasma, which does not waste energy on the rise of gas temperature, and the uniformity of the discharge is high. DBD was first used in industrial ozone generators/wastewater treatment/sterilization, but recent research and applications are mainly used for cleaning and activating large-area substrates. The biggest advantage of DBD is that it can be large-scaled. Therefore, large-area atmospheric pressure plasma systems are usually made in DBD mode, but its disadvantage is that the plasma density is much lower than that of jet plasma, so it needs to be able to target different Different DBD electrode structures are designed to improve the efficiency of plasma processing. Therefore, professional knowledge and technological innovation are very important to have the best design. The wide-format atmospheric DBD plasma (Remote type) developed by Yangzhou Guoxing Technology Co., Ltd. is different from the dot-type plasma (Arc-Jet). The plasma width can be adapted to different sizes (G1~G8 LCD). ) The requirements are optimized, and cheap N2/CDA is used as the reaction gas. The running cost of the equipment is less than 1/5 of the general UV-Ozone clean. Example Figure 5 shows the results of the water drop angle test after the large-area ITO glass is processed by the DBD plasma equipment (Figure 4). It can be found that the cleanliness/wettability of the substrate surface has been significantly improved after the atmospheric plasma treatment. Subsequent bonding/coating/wet cleaning/wet etching/plating chemical exchange process is of decisive benefit. In recent years, some scholars have claimed that the filamentary discharge of DBD can be improved, and one atmospheric uniform glow discharge plasma that is as stable as low-pressure glow discharge can be obtained by controlling the discharge parameters. Since this atmospheric pressure glow discharge plasma is very uniform, there is no electric wire formed by filamentary discharge due to uneven plasma, so it will not damage the fragile material surface. However, it must be in a special gas environment to produce uniform plasma. Expensive inert gases such as He and Ne are required, and high-frequency and high-voltage power supplies are required. The production is difficult, the life is limited, and it is difficult to reproduce. It is officially adopted by the industry. 3. Corona discharge The corona discharge system adopts the tip discharge method, which uses a concentrated electric field at the tip to cause the gas breakdown (Breakdown) effect to produce a dissociation reaction. It is basically composed of one needle electrode and the other flat electrode, between the two electrodes Applying a voltage will form a discharge between the electrodes. 4. Plasma torch The common Plasma torch electrode design is connected with a high-current DC or RF power supply (tens of volts, hundreds of amperes of current), and gas is passed in through the side to generate a high-speed airflow between the electrodes to stabilize the plasma. Push to the outlet to produce a plasma torch with extremely high temperature. The flame center temperature can be as high as tens of thousands of K. This method can effectively decompose harmful gas waste. But because this is to raise the gas temperature to produce dissociation, similar to the thermal cracking method, although there are no follow-up problems such as reactor life, and the equipment is simpler, it consumes a lot of energy and is not an economical method. Current applications include: material processing and welding, waste gas treatment, pollutant reduction, organic matter removal and plasma spraying... etc. You can understand the above four categories. Guoxing Technology will always maintain a keen observation of the market, based on technological innovation, and contribute to Jiangdu, Yangzhou, and the motherland’s intelligent manufacturing development. Technology revitalizes the country"! We will also give full play to the team’s ingenuity and work hard to achieve the mission of "making electronics manufacturing easier"!