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Nine requirements for three anti-paint coating

Release time2019-07-30 Read1477
CBA three anti-paint is a common circuit board protective coating. It is an essential anti-aging protective paint for electronic equipment circuit boards working in harsh environments. It is also called three anti-adhesive, circuit board coated rubber, PCBA protective oil, PCBA waterproof rubber, PCBA. Insulating varnish, because PCBA has waterproof, moisture-proof, shock-proof, anti-corrosion, dust-proof, anti-static, etc., and the conventional demand is PCBA waterproof, moisture-proof and anti-corrosion three-proof, so it is called "PCBA three anti-paint", in fact, it is more anti-paint .
Because the three anti-paint is coated on the surface of the circuit board, the shape is like paint, so more people call it three anti-paint, and then carefully study its composition. In fact, there are many types of anti-paint, such as polyurethane, acrylate, silicon. . What are the requirements for the three anti-paints when coating? Let's take a closer look:

First, what are the coating methods for PCBA three anti-paint?
1. Dipping: It is economical for large equipment, but the thickness after coating will be affected by factors such as temperature, time, speed of extraction, time of convection, air knife, etc., and sometimes some The influence of component characteristics cannot be impregnated.
2. Spraying: economical for small and medium-sized equipment. When spraying, it is like painting. The uniformity of coating depends on the speed of relative movement, the location of spraying, the pressure of spraying, and whether there are higher parts. In addition, the bottom of the part cannot be sprayed and additional processing may be required.
3. Brushing: It is economical for small equipment. When coating, it is easy to cause uneven coating due to the skill of coating, and also pay attention to the problem of hair brush hair loss. The bottom of the part is also difficult to coat.
4. Selective Coating: Although the coating has many advantages, it is often time-consuming and labor-intensive. It can also be selected in some parts where it is needed. Some three-coat paint spraying machine can be set by program to Selective coating .It’s much more convenient than manual coating.

Second, what are the operational requirements for coating PCBA three anti-paint?
1. The three-proof work should be carried out in a separate room, but it should not be completely sealed, and there must be good ventilation.
2. Do not smoke, eat or drink in the operation room. Do not quote alcoholic beverages before work.
3. Wear masks or gas masks, rubber gloves, chemical protective glasses and other protective equipment to avoid injury to the body, which also depends on the choice of three anti-paint products, if it is a stupid product, you must pay great attention to protection And fire prevention, and if it is TIS-NM environmental protection three anti-paint products, the safety is much higher, there is no risk of burning.
4. After the work is finished, it is necessary to clean the used utensils in time, arrange and test the tools and equipment, and cover the container with the three anti-paint.
5. The workplace should be clean and dust-free, no dust flying, and prohibit unrelated personnel from entering.
6. Tools and equipment should be fully grounded and electrostatic protection measures should be taken.
7. Do not place PCBA on top of each other during operation; PCB board should be placed horizontally.
8. Each batch of raw materials should be tested for a small sample before use(3 - 5PCS).

Third, what tools do you need to apply PCBA three anti-paint?
Three anti-paint, paint box, rubber gloves, mask or gas mask, brush, espresso tape, tweezers, ventilation equipment, drying rack, oven.

Fourth, what are the process requirements for coating PCBA three anti-paint?
1. Clean and bake the board to remove moisture and moisture. The dust, moisture and rosin on the surface of the PCBA board must be removed before brushing, so that the three anti-paint adheres well to the surface of the board. Drying conditions: 60 ° C, 30-40 minutes, after the removal in the oven, the hot coating effect is better.
2. According to the product size and the layout of the board components, use the brush correctly, pour the three anti-paint into the container, and then use the brush to glue the appropriate glue to evenly brush the circuit board.
3. The area of the brush should be larger than the area occupied by the device to ensure that all the devices and pads are covered.
4. When the brush is applied, the PCBA board should be placed as flat as possible. After brushing, there should be no dew. The brush should be flat and there should be no exposed parts. The thickness of the brush should be between 0.1-0.3mm.
5. After brushing, the more inserting components are placed horizontally on the air drying rack to dry and solidify (the heating method can accelerate the coating).
6. When applying three anti-paint to the PCB, all connected plug-in devices, sockets, switches, heat sinks (chips), heat-dissipating areas, etc. (not to be painted with three anti-paint components see note) are not allowed to apply three anti-paint Use a mask to protect the paint.
7. If a thicker coating is desired, it can be obtained by applying two thinner coatings (required that the second layer must be applied after the first layer has completely dried).

Fives, What are the technical requirements for coating PCBA three anti-paint?
1. Brush three anti-paint protection must be tested, inspected and thoroughly cleaned before PCBA assembly.
2. The brush used should be kept clean, it is forbidden to be used for other operations; when painting the brush, be careful not to drip to the part that does not need to be painted; the brush after use should be cleaned with thinner material.
3. The coating layer should be transparent, and evenly cover the PCB board and components, uniform color and consistency.
4. The process steps are: brush A surface → dry surface → brush B surface → room temperature curing
5. Spraying thickness: spraying thickness is 0.1mm-0.3mm
6. All coating operations should be carried out at a temperature not lower than 16 ° C and a relative humidity lower than 75%. PCB as a composite material will absorb moisture. If it does not remove moisture, the three anti-paint can not fully protect it. Pre-drying and vacuum drying can remove most of the moisture.

Sixth, what are the precautions for coating PCBA three anti-paint?
1. The three anti-paints are not allowed to be used beyond the shelf life.
2. The storage container should be sealed and stored after opening.
3. It is forbidden to return the remaining three anti-paints to the original storage container, and keep them separately.
4. If the working room or storage room is not opened for a long time (more than 12 hours), it should be ventilated for 15 minutes before entering.
5.Accidentally splashed into the glasses should immediately open the upper and lower eyelids, rinse with running water or saline, and then seek medical treatment.
6. If you feel uncomfortable during brushing, you should quickly leave the job site to the fresh air. Give oxygen when you have difficulty breathing, and then seek medical attention.

Seventh,What are the quality requirements for coating PCBA three anti-paint?
1. There should be no flow paint or dripping on the surface of the PCB, and there should be no semi-wetting phenomenon.
2. The three anti-paint layer should be flat, bright, thin and even, and protect the surface of the pad, the paste component or the conductor.
3.The surface of the paint layer can not have orange peel, bubbles, pinholes, ripples.
4. No need to apply three anti-paint on the parts or components that do not need protection.
5. The printed board after three preventions should be clean and tidy, and there is no component damage.
6. There are no defects such as dirt, fingerprints, corrugations, shrinkage holes, dust and other foreign objects on the board surface and components, no powdering and no peeling.

Eight, which components of PCBA can not be coated with three anti-paint?
1. High power with heat sink or heat sink assembly, power resistor, power diode, cement resistor.
2. DIP switch, adjustable resistor, buzzer, battery holder, fuse holder (tube), IC holder, tact switch.
3. All types of sockets, pin headers, terminal blocks and DB heads.
4. Plug-in or stick-type LED, digital tube.
5. Other parts and devices that are not allowed to use insulating varnish as specified in the drawings.
6. the screw hole of the PCBA board can not be painted with three anti-paint.

Ninth. What are the storage requirements for coating PCBA three anti-paint?
1. Raw materials should be stored in a cool, dry warehouse (room temperature should not exceed 30 degrees), and explosion-proof ventilation systems and equipment should be installed, and should be kept away from heat sources.
2. To be stored separately from other types of chemicals, and to have a clear material identification, avoid mixing.
3. Pay attention to fire prevention, and equipped with fire equipment.
4. The storage warehouse should be equipped with leaking emergency equipment and reasonable containment materials (such as sand).
5. The warehouse should be kept ventilated to prevent the accumulation of leaking gas and cause accidents.
6. The effective date of use should be indicated on the storage container.
7. Storage shelves or equipment should be well grounded. It is forbidden to use equipment and tools that are prone to sparks.