What is triple-proof paint?

1. What is conformal coating and what are the conformal coatings? Conformal coating is a specially formulated coating that protects the printed circuit board and its associated equipment from environmental aggressors. Conformal coating has good resistance to high and low temperatures; After curing, it will form a transparent protective film, which has excellent insulation, moisture-proof, leakage-proof, shock-proof, dust-proof, anti-corrosion, anti-aging, corona resistance and other properties. Conformal coating is widely used in the electronics manufacturing industry, and there are many conformal coatings with different components such as acrylic and polyurethane on the market. Conformal coating is also known as PCB electronic circuit board protective oil, protective oil, electronic waterproof adhesive, circuit board coating oil, circuit board moisture-proof paint, conformal coating, insulating paint, anti-corrosion paint, anti-salt spray paint, dustproof paint, protective paint, coating paint, conformal adhesive, etc.

So what are the three conformal coatings? In the strict sense, there is no definition, the word "three" is taken from the meaning of the ancient word "many", that is, the meaning of multi-faceted protection, in the daily application of conformal coating basically has waterproof, moisture-proof, dust-proof "three-proof" performance, in addition to both cold and thermal shock resistance, aging resistance, radiation resistance, salt spray resistance, ozone corrosion resistance, vibration resistance, good flexibility, strong adhesion and other properties, because of its low technical content, cheap price, in the low-end products of the application is more common.

2. The role of conformal coating Conformal coating is a specially formulated coating used to protect circuit boards and related equipment from environmental erosion, so as to enhance and extend their service life and ensure the safety and reliability of use. Under realistic conditions, such as chemical environment (fuel, coolant, etc.), vibration, high dust, salt spray, humidity and high temperature, the circuit board may be corroded, softened, deformed, mildewed and other problems, resulting in circuit board failure. Conformal coating is applied to the surface of the circuit board to form a flexible film with a thickness of about 50 to 100 microns, which can protect the circuit from damage under relatively harsh conditions.

3. Characteristics of conformal coating

<!--[if !supportLists]-->1.<!--[endif]-->One-component, low-viscosity resin, suitable for brushing, spraying, dipping, spraying and other processes, with good adhesion.

<!--[if !supportLists]-->2.<!--[endif]-->It has good resistance to high and low temperatures; After curing, a transparent protective film is formed, which has the properties of insulation, moisture-proof, leakage-proof, shock-proof, dust-proof, anti-corrosion, anti-salt spray, anti-mildew, anti-aging, and corona resistance.

Fourth, the use of conformal coating The conformal coating covers the surface of the circuit board to form a film 50 - 100 microns thick. It protects circuits from damage in conditions such as chemicals (e.g., fuels, coolants, etc.), vibration, moisture, salt spray, humidity and high temperatures. Under these conditions, the circuit board can be corroded, molded, and short-circuited, which can lead to the failure of circuits without conformal coating. Conformal coating is mainly used in daily applications: color TV, refrigerator, washing machine, microwave oven, air conditioner, telephone, electric water heater and other ordinary household appliances and electronic products integrated circuit protection, with strong adhesion, waterproof, lightning protection, rust prevention, corrosion prevention and other properties, can greatly improve the performance stability of household appliances.

5. Process requirements for conformal coating (1) Conformal coating construction process

<!--[if !supportLists]-->1.<!--[endif]-->Brushing – This is the simplest conformal coating process and produces excellent coating results on smooth surfaces.

<!--[if !supportLists]-->2.<!--[endif]-->Spraying - spraying method is the most commonly used coating method in the industry, and it is divided into two types: automatic spraying by machine and manual spraying. Machine spraying can realize automatic feeding, save labor and material costs, improve production efficiency, and ensure product consistency, product quality and surface spraying effect.

<!--[if !supportLists]-->3.<!--[endif]-->Dipping – Dipping ensures complete film overlay and no material waste due to overspraying.

<!--[if !supportLists]-->4.<!--[endif]-->Selective coating - accurate coating and no waste of material, suitable for large batches of lamination, but high requirements for coating equipment, most suitable for large quantities of lamination. Use a compiled XY table to reduce masking. When painting the PCB board, there are many connectors that do not need to be painted, the adhesive paper is too slow and there is too much residual glue when tearing, you can consider making a combined cover according to the shape, size and position of the connector, and use the mounting hole to locate and cover the parts that do not need to be painted.

(2) Precautions during operation

<!--[if !supportLists]-->1.<!--[endif]-->Clean and dry the plates, remove moisture and moisture. Dust, moisture and oil must be removed from the surface of the object to be coated in order to give full play to its protective effect. Thorough cleaning ensures that corrosive residues are completely removed and that the conformal coating adheres well to the PCB surface. Drying conditions: 60°C, 10 - 20 minutes, remove from the oven and apply while hot for better results.

<!--[if !supportLists]-->2.<!--[endif]-->When applying conformal coatings using the brush coating method, the brush area should be larger than the area occupied by the device to ensure complete coverage of the device and pads.

<!--[if !supportLists]-->3.<!--[endif]-->When brushing the conformal coating, the circuit board should be placed as flat as possible, and there should be no drip after brushing, and the brushing should be smooth, and there should be no exposed parts, and 0.1 - 0.3mm is appropriate.

<!--[if !supportLists]-->4.<!--[endif]-->Before brushing and spraying conformal coating, make sure that the diluted conformalcoating is well stirred and leave for 2 hours before brushing or spraying. Using a high-quality natural fiber brush, apply the dip coat gently at room temperature. If mechanical is used, the viscosity of the paint should be measured (using a viscosity agent or flow cup), and the viscosity can be adjusted with a diluent.

<!--[if !supportLists]-->5.<!--[endif]-->The PCB assembly should be vertically immersed in the paint tank. Do not immerse the connector, unless carefully covered, the circuit board should be immersed for 1 minute until the bubbles disappear, and then slowly take it out, the surface of the circuit board will form a uniform film. Most of the paint residue should be allowed to flow back to the impregnation machine from the circuit board, and the circuit board or components should not be immersed too quickly to avoid excessive air bubbles.

<!--[if !supportLists]-->6.<!--[endif]-->If there is crusting on the surface after dipping and re-application, the epidermis can be removed and continued to be used.

<!--[if !supportLists]-->7.<!--[endif]-->If the coating surface is uneven or contains bubbles, it should be placed at room temperature for more time before curing in a high-temperature furnace to allow the solvent to flash out.

(3) Operating environment requirements

<!--[if !supportLists]-->1.<!--[endif]-->The application of conformal coating should be carried out in a separate closed room, and the operation room must have good ventilation facilities.

<!--[if !supportLists]-->2.<!--[endif]-->Smoking, eating, drinking, and drinking are prohibited in the operation room, and alcoholic beverages are not consumed before work.

<!--[if !supportLists]-->3.<!--[endif]-->Wear protective equipment such as masks or gas masks, rubber gloves, and chemical protective glasses when operating to avoid harming the body.

<!--[if !supportLists]-->4.<!--[endif]-->After the work is completed, the used utensils should be cleaned in time, the tools and equipment should be sorted and wiped, and the containers with conformal paint should be tightly covered.

<!--[if !supportLists]-->5.<!--[endif]-->The workplace should be clean and dust-free, free of dust, and unrelated personnel should be prohibited from entering.

<!--[if !supportLists]-->6.<!--[endif]-->Tools and equipment should be fully grounded, and electrostatic protection measures should be taken.

<!--[if !supportLists]-->7.<!--[endif]-->Do not place the circuit boards on top of each other during operation; The PCB board should be placed horizontally.

<!--[if !supportLists]-->8.<!--[endif]-->Before each batch of raw materials is used, a sample curing test should be done.

(4) Where conformal paint should not be applied

<!--[if !supportLists]-->1.<!--[endif]-->High power with heat dissipation surface or heat sink element, power resistor, power diode, cement resistor.

<!--[if !supportLists]-->2.<!--[endif]-->DIP switches, adjustable resistors, buzzers, battery holders, fuse sockets (tubes), IC sockets, tactile switches.

<!--[if !supportLists]-->3.<!--[endif]-->All types of sockets, pin headers, terminal blocks and DB headers.

<!--[if !supportLists]-->4.<!--[endif]-->Plug-in or stick-type light-emitting diodes, digital tubes.

<!--[if !supportLists]-->5.<!--[endif]-->Other parts and devices that are not allowed to use insulating paint as specified in the drawings.

<!--[if !supportLists]-->6.<!--[endif]-->The screw holes of the circuit board should not be coated with conformal coating.

(5) Requirements for PCB boards coated with conformal coating

<!--[if !supportLists]-->1.<!--[endif]-->There should be no paint flowing, dripping and semi-wetting on the surface of the circuit board.

<!--[if !supportLists]-->2.<!--[endif]-->The conformal coating layer should be smooth, bright, and evenly thick, and protect the surface of pads, adhesive components or conductors.

<!--[if !supportLists]-->3.<!--[endif]-->The surface of the paint layer should not have orange peel shape, bubbles, pinholes, and ripples.

<!--[if !supportLists]-->4.<!--[endif]-->Conformal coating is not required on devices or components that do not require protection.

<!--[if !supportLists]-->5.<!--[endif]-->The printed board after the three proofs should be clean and tidy, and there should be no component damage.

<!--[if !supportLists]-->6.<!--[endif]-->There are no defects and foreign substances such as dirt, handprints, corrugations, shrinkage holes, dust and other defects on the board surface and components, and there is no chalking and peeling.

6. The difference between conformal coating and PCB nano coating Although conformal coating also has many characteristics and advantages, it can make electronic products have moisture-proof, leakage-proof, shock-proof, dust-proof and other properties, but with the development of science and technology and the increasing improvement of people's material living standards, consumers have put forward more requirements for product quality, and people are no longer satisfied with a simple three-proof product, but need to meet more needs for environmental protection, health, lightweight, etc. Regulators in relevant countries and economies have also been strengthened, barriers to entry have been raised, and manufacturing companies that use low-end materials to produce low-quality products face greater challenges to survive. More and more high-end manufacturing industries are aware of this and are constantly investing in R&D to improve quality, starting to use more advanced and cutting-edge materials and technologies. Nano moisture-proof and anti-corrosion coating is an advanced representative of PCB waterproof, moisture-proof and anti-salt spray corrosion materials, nano coating not only has the basic protective characteristics of conformal coating, but also solves some problems that cannot be solved by conformal coating, and greatly improves the protection and environmental performance. As the industry pioneer of PCB nano coating, nano moisture-proof coating has always led the market direction, and its products have been tested by many domestic listed companies.

Through the above detailed elaboration of conformal coating, the following can be summarized:

<!--[if !supportLists]-->·       <!--[endif]-->Definition and protective performance: conformal coating is a special coating to protect circuit boards and related equipment from environmental erosion, although there is no strict definition of "three proofs", but the daily basic waterproof, moisture-proof, dust-proof functions, but also a variety of other properties, because of low technical content, low price in low-end products are widely used.

<!--[if !supportLists]-->·       <!--[endif]-->Function: Protect the circuit board and its related equipment from harsh environmental erosion, improve and prolong its life, and ensure the safety and reliability of use.

<!--[if !supportLists]-->·       <!--[endif]-->Features: One-component, low-viscosity resin, suitable for a variety of processes and good adhesion, cured into a transparent protective film, with a variety of protective properties.

<!--[if !supportLists]-->·       <!--[endif]-->Uses: It is used for the protection of integrated circuits of a variety of home appliances and electronic products to improve the stability of product performance.

<!--[if !supportLists]-->·       <!--[endif]-->Process requirements

<!--[if !supportLists]-->·       <!--[endif]-->Construction technology: including brushing, spraying, dipping, and selective coating, each with its own characteristics and applicable scenarios.

<!--[if !supportLists]-->·       <!--[endif]-->Precautions for operation: cleaning the drying plate, specific requirements for different coating methods, treatment when re-use, etc.

<!--[if !supportLists]-->·       <!--[endif]-->Operating environment requirements: separate closed room operation, good ventilation, wearing protective equipment, finishing and cleaning after work, etc.

<!--[if !supportLists]-->·       <!--[endif]-->Non-coated places: specific components and parts such as high-power heat dissipation elements.

<!--[if !supportLists]-->·       <!--[endif]-->Requirements after coating: there can be no undesirable phenomena on the surface, protect the relevant components and keep the board surface clean and tidy.

<!--[if !supportLists]-->·       <!--[endif]-->Different from PCB nano coating: conformal coating has many properties, but with the increase in demand, nano moisture-proof and anti-corrosion coating, as an advanced representative, in addition to the basic protective characteristics, also solves the problem that conformal coating can not solve, improve protection and environmental performance, and high-end manufacturing industry gradually begins to use this more advanced technology.