Three anti-paint is a specially formulated coating to protect the circuit board and its related equipment from the environment. The three anti-paint has good resistance to high and low temperature; it cures into a transparent protective film, such as in the case of chemicals (eg fuel, coolant, etc.), vibration, moisture, salt spray, humidity and high temperature. Protect circuits from damage. Under these conditions, the circuit board may be corroded, mold growth and short circuit, etc., with superior insulation, moisture, leakage, dust, corrosion, anti-aging, anti-mold, anti-part loose and insulation corona resistance. .
Three anti-paint effectMoisture is the most common and destructive factor for PCB boards. Excessive moisture greatly reduces the insulation resistance between the conductors, accelerates high-speed decomposition, lowers the Q value, and corrodes the conductor. We often see that the metal part of the PCB circuit board is made of patina or is not coated with three anti-paint metal copper and steam, oxygen and its chemical reaction.
Applying three anti-paint to printed circuit boards and components can reduce or eliminate electronic operating performance degradation when it is likely to be affected by adverse operating conditions. If the lacquer can maintain its effect for a satisfactory period of time, such as greater than the life of the product, it can be considered as having reached its purpose of coating.
Three anti-paint componentsThe acrylic acrylic three-coat paint is flexible and provides comprehensive protection. Because it is a one-component system, it has good adhesion, simple operation, low requirements on equipment and conditions, convenient construction, high transparency, high brightness, short operating cycle, etc., so they are easy to use and easy to remove. Some acrylic products meet military standards, they dry quickly and do not dry, and can be removed with a matching organic solvent, so this type of circuit board three anti-paint is one of the most versatile and most effective products on the market.
Is the three anti-paint toxic?Whether the three anti-paints are toxic depends on the type of three anti-paint and the solvent used. If the three anti-paints use toluene and xylene as diluents, this chemical is harmful to the human body. If lipids, alcohols, etc. are used, Smaller. Xylene is moderately toxic and has a stimulating effect on the eye and upper respiratory tract. At high concentrations, it has an anesthetic effect on the central nervous system.
Although there are many environmentally-friendly three-proof paints on the market, in actual use, we still need to take protective measures and wear gas masks when using them.
There are four types of three anti-paint use processes:
1, brushing - the use of universal, can produce an excellent coating effect on a smooth surface.
2, spraying - the use of spray can type products can be easily applied to maintenance and small-scale production use, the spray gun is suitable for large-scale production, but these two spray methods require higher accuracy of operation, and may produce Shadow (the place where the lower part of the component is not covered with three anti-paint).
　　
3, automatic dip coating - dip coating to ensure complete filming, and will not cause material waste caused by over-spraying.
4. Selective coating of the film - accurate coating and no waste of material, suitable for large-volume coating, but high requirements for coating equipment. Most suitable for large-volume coatings. Use a prepared XY table to reduce cloaking. When the PCB is painted, there are many connectors that do not need to be painted. The adhesive tape is too slow and there is too much residual glue when tearing. Considering the shape, size and position of the connector, make a combined cover and position it with the mounting hole. Cover the parts that are not painted.
　　
Three anti-paint operation process requirements
1. Clean and bake the board to remove moisture and moisture. The dust, moisture and oil on the surface of the object to be coated must be removed first so that it can fully exert its protective effect. Thorough cleaning ensures that corrosive residues are completely removed and the three anti-paints adhere well to the surface of the board. Drying conditions: 60 ° C, 10-20 minutes, after removing in the oven, the hot coating effect is better;
2. Apply by brushing method, the brushing area should be larger than the area occupied by the device to ensure that all the devices and pads are covered;
3, when the brush is applied as flat as possible, there should be no dew after brushing, the brush should be flat, and there should be no exposed parts, preferably between 0.1-0.3mm.
4. Before brushing and spraying, ensure that the diluted product is thoroughly stirred and allowed to stand for 2 hours before brushing or spraying. Use a high quality natural fiber brush and gently apply a dip coating at room temperature. If using machinery, the viscosity of the coating should be measured (using a viscosity agent or flow cup) and the viscosity can be adjusted with a diluent.
5. The board assembly should be immersed vertically into the paint slag. Do not immerse the connector, unless carefully covered, the board should be immersed for 1 minute until the bubble disappears, then slowly take out. A uniform film layer is formed on the surface of the board. Most of the paint residue should flow back from the board to the dipper. TFCF has different coating requirements. The board or component should not be immersed too fast to avoid excessive air bubbles.
　　
6. When using again after dip coating, if there is skin on the surface, remove the epidermis and continue to use.
7. After brushing, lay it on the bracket and prepare to cure. It is necessary to use heating to accelerate the curing of the coating. If the surface of the coating is uneven or contains air bubbles, it should be allowed to stand at room temperature for more time to solidify in a high temperature furnace to allow the solvent to flash out.
Precautions:
1. If a thicker coating is desired, it is best to obtain it by applying two thinner coatings - and it is necessary to allow the second layer to be applied after the first layer has completely dried.
2. When coating the PCB, the general connector, software socket, switch, heat sink, heat dissipation area, board area, etc. are not allowed to have coating materials. It is recommended to use a tearable solder mask to cover.
3 , the thickness of the film: the thickness of the film depends on the application method. The diluent is added in a large amount, the viscosity of the glue is low, and the thickness of the glue is thin; on the contrary, the viscosity of the glue is high, and the thickness of the glue is thick.
4, all of the coating process should be not less than 16 deg.] C and a relative humidity of less than 75% of conditions. PCB as a composite material will absorb moisture. If you do not go to the tide, the three anti-paint can not fully protect. Pre-drying and vacuum drying remove most of the moisture.
　　
Repair the already coated device method
If you are repairing an already coated device, simply remove the soldering iron directly into the coating and remove the component. After installing the new component, clean the area with a brush or solvent, then dry and reuse the coating. Coated.
A port is an interface through which data is transferred between a computer and other devices (such as printers, mice, keyboards or monitors), networks, or other directly connected computers.
For the CPU, the port is used as one or more memory addresses for sending or receiving data. Dedicated hardware, such as an additional circuit board, places the data from the device in a memory address, and sends the data from the memory address to the device. Ports can be dedicated for input and output only. The port usually receives a specific type of plug for a specific purpose. For example, serial data interfaces, keyboards, and high-speed network ports all use different connectors, so it is impossible to plug the cable into the wrong port.
In programming, a port is a "logical connection location", especially in the Internet Protocol TCP/IP, a way for the client program to be assigned to a special service program on the computer. High-level applications that use TCP/IP protocols such as web protocol and hypertext transfer protocol have specially designated ports. From the perspective of port allocation, ports are divided into two categories: fixed ports and dynamic ports: Fixed ports (0~1023): use a centralized management mechanism, that is, subject to the assignment of ports by a management organization, which is responsible for issuing these assignments . Because these ports are closely tied to some services, we will often scan these ports to determine whether the other party has enabled these services, such as TCP 21 (ftp), 80 (http), 139 (netbios), UDP 7 (echo), 69 (tftp) and other well-known ports; Dynamic ports (1024~49151): These ports are not fixedly bound to a certain service. The operating system dynamically allocates these ports to each process, and the same process is allocated twice It is possible to assign to different ports. However, some applications are reluctant to use the dynamic ports allocated by the operating system. They have their own "branded" ports, such as port 4000 of the oicq client and port 7626 of the Trojan Binghe, which are all fixed and famous.
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