PCBA three-proof paint coating standard and three-proof paint coating equipment selection
Date: 2018/6/26 21:43
PCBA three-proof paint is also called PCBA protective oil, PCBA waterproof glue, PCBA insulating paint, because it has three functions of waterproofing, moisture-proof and dust-proof to PCBA, it is called "PCBA three-proof paint".
What are the coating methods of PCBA three-proof paint?
1. Dipping: It is more economical for large equipment, but the thickness after coating will be affected by factors such as the temperature, time, extraction speed, vertical flow time, whether or not air knife is added.
2. Spraying: It is more economical for small and medium equipment. When using spraying, it is like spraying paint. The uniformity of coating depends on the relative moving speed, spraying position, spraying pressure, and whether there are higher parts. In addition, the bottom of the part cannot be sprayed and may require additional treatment.
3. Brushing: It is more economical for small equipment. When applying, it is easy to cause uneven application due to the proficiency of the coating technique. In addition, pay attention to the problem of hair loss caused by the brush. It is also difficult to coat the bottom of the part.
4, Selective Coating (Selective Coating): Although the coating has many advantages, it is often time-consuming and labor-intensive. You can also choose the part where you need to apply.
What tools do I need to apply PCBA coating?
Three anti-paints, paint boxes, rubber gloves, masks or gas masks, hair brushes, art paper, tweezers, ventilation equipment, drying racks, ovens.
What are the technical requirements for PCBA coating?
1. Brush three anti-paint protection must be tested, inspected, and thoroughly cleaned before PCBA assembly.
2. The used brushes must be kept clean and not allowed to be used for other operations. When painting the brushes, be careful not to drip to the parts that do not need to be painted. The brushes after use should be cleaned with thin materials.
3. The coating layer should be transparent and cover the PCB board and components evenly, with uniform color and consistency.
4. The process steps are as follows: painting A side → surface drying → painting B side → room temperature curing
5. Spray thickness: The spray thickness is 0.1mm-0.3mm
6. All coating operations should be performed at a temperature of not less than 16 ° C and a relative humidity of less than 75%. PCB as a composite material will absorb moisture. If it does not dehumidify, the three anti-paint can not fully protect, pre-drying, vacuum drying can remove most of the moisture.
What are the process requirements for coating PCBA three-proof paint?
1. Clean and bake boards to remove moisture and moisture. Before brushing, the dust, moisture and rosin to be painted on the surface of the PCBA board must be removed to make the three-proof paint adhere to the surface of the circuit board well. Baking conditions: 60 ° C, 30-40 minutes. After taking out in the oven, the coating effect is better while it is hot.
2. Choose the correct brush according to the size of the product and the layout of the board components, pour the anti-proof paint into the container, and then apply the brush to the appropriate glue to uniformly coat the circuit board.
3. The brushing area should be larger than the area occupied by the device to ensure that the device and the pad are completely covered.
4. The PCBA board should be placed as flat as possible during brushing. There should be no dew after brushing. The brushing should be flat and there should be no exposed parts. The thickness of the brushing should be between 0.1-0.3mm.
5. After brushing, many plug-in components are placed horizontally on the air-drying rack for surface curing (the heating method can accelerate the curing of the coating).
6. When applying the three-proof paint on the PCB, all connected plugging devices, sockets, switches, heat sinks (slices), heat dissipation areas, etc. (not applicable for the three-proof paint components, see note) are not allowed to be painted with the three-proof paint. Yes, you need to use masking paper to protect it when painting.
7. If a thicker coating is desired, it can be obtained by applying two thinner coatings (requires that the first layer must be completely dried before the second layer is allowed to be applied).
What are the operational requirements for applying PCBA three-proof paint?
1. Three-proof work should be carried out in a separate closed room, and there must be good ventilation facilities in the operation room.
2. Smoking, eating and drinking are prohibited in the operation room. Do not use alcoholic beverages before work.
3. Wear protective equipment such as masks or gas masks, rubber gloves, chemical protective glasses, etc. to avoid harm to the body.
4. After the work is completed, clean the used utensils in time, organize and test the tools and equipment, and tightly cover the container with the three-proof paint.
5. The workplace should be clean and dust-free, no dust flying, and irrelevant personnel are prohibited from entering.
6, tools and equipment should be fully grounded, and good electrostatic protection measures.
7. Do not place PCBA on top of each other during operation; PCB boards should be placed horizontally.
8. Before each batch of raw materials is used, a sample solidification test (3-5 PCS) should be performed.
What are the quality requirements for coated PCBA three-proof paint?
1. There should be no paint flow or dripping on the PCB surface, and no semi-wetting phenomenon.
2. The three-proof paint layer should be flat, bright, and evenly thick, and protect the surface of the pads, stick components or conductors.
3. There should be no orange peel, bubbles, pinholes or ripples on the surface of the paint layer.
4, no need to protect the components or components do not need to paint three anti-paint.
5. The printed board after the three defenses should be clean and tidy without damage of components.
6. There are no dirt, fingerprints, ripples, shrinkage holes, dust and other defects and foreign objects on the board surface and components, and there is no chalking or peeling.
What are the storage requirements for PCBA coating?
1. Raw materials should be stored in a cool, dry warehouse (room temperature should not exceed 30 degrees), explosion-proof ventilation systems and equipment are installed, and should be kept away from heat sources.
2. It should be stored separately from other types of chemicals, and must have a clear material identification, and must not be mixed.
3. Pay attention to fire prevention and equip with fire fighting equipment.
4. Storage warehouses should be equipped with leak emergency equipment and reasonable containment materials (such as sand).
5. The warehouse should be ventilated to prevent accidents caused by the accumulation of leaked gas.
6. The storage container should indicate the effective use date.
7, storage shelves or equipment should be well grounded, the use of equipment and tools that are prone to sparks is prohibited.
What precautions should be taken when applying PCBA anti-proof paint?
1. The three-proof paint has exceeded the shelf life, and it is prohibited to use it.
2. The storage container should be kept tightly closed after opening.
3. It is forbidden to return the remaining three anti-paints to the original storage container, and keep them separately and sealed.
4. If the work room or storage room has not been 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 physiological saline, and then seek medical treatment.
6. If you feel uncomfortable when brushing, you should quickly leave the job site to fresh air, give oxygen when breathing is difficult, and then seek medical treatment.
Which components of PCBA cannot be coated with three anti-paints?
1. High power with heat dissipation surface or heat sink component, power resistor, power diode, cement resistor.
2. Dip switch, adjustable resistor, buzzer, battery holder, insurance holder (tube), IC holder, touch switch.
3. All types of sockets, pin headers, terminal blocks and DB headers.
4, plug-in or stick light-emitting diodes, digital tubes.
5, other parts and devices specified in the drawing that can not use insulation paint.
6. The screw holes of PCBA boards cannot be painted with anti-paint.