1. The three-proof paint requires the lowest viscosity to meet the “spraying” ability requirements, while the dipping method demands the highest viscosity for the three-proof paint. The viscosity of the three-proof paint is determined by its solid content. Manufacturers of three-proof paint typically have their own thinners for diluting products to different concentrations, catering to various coating process requirements. Bo Yi Sheng’s PCBA cleaning machine uses a fully pneumatic method and does not require an external power source, thus eliminating fire risk. Additionally, it employs environmentally friendly water-based solvents that pose no harm to the environment or human health, making it both safe and eco-friendly.

2. PBT engineers discuss PCBA’s three-proof coating technology.

3. The basic coating methods for three-proof paint usually include hand spraying, dipping, and brushing. While these methods are simple and do not require significant equipment investment, they often result in inconsistent coating quality. Issues such as poor film thickness, substantial paint loss, environmental pollution, and accidental contamination of adjacent sockets can occur. Selective spraying may be challenging and may necessitate manually applying adhesive paper to protect certain devices before coating. Additionally, some gaps between components and their sides may be difficult to coat properly. These problems impact product quality and need urgent attention. Selective active coating machines provide an ideal solution, offering precise PCBA spraying, avoiding non-paintable components, and ensuring uniform coating thickness.

4. To ensure high-quality three-proof coating, selective active coating equipment should meet the following technical parameters and performance requirements:

1. On-line fully automated flow operation to minimize manual handling;

2. Capable of point/line/surface/arc/circle continuous connection of irregular curves and three-axis linkage;

3. Ability to accommodate multiple different spraying heads simultaneously, with automatic switching based on varying spraying requirements to cover diverse areas;

4. Optional CCD vision centering system to correct PCBA or fixture positioning errors, enhancing spraying accuracy;

5. Accurate control of the three-proof paint’s spraying volume.

5. To achieve a high-quality three-proof coating, the following process requirements must be met:

1. For components that should not be coated with three-proof paint, such as connectors, buttons, LEDs, and gold fingers, masking tape must be applied during brush coating, dipping, or manual spraying. Even when using a fully automated selective coating machine, if the coating area is too close (less than 5 mm) to non-coatable positions, barrier precautions must be taken.

2. Prior to coating, the PCBA surface must be cleaned to remove any contaminants. For products with stringent requirements, such as those in automotive, aerospace, maritime, and military sectors, PCBA should be washed and dried before coating. For general products, high-pressure dry air can be used to remove surface dust and dirt.

3. Before initiating mass production with the selective active coating machine, a thorough inspection of the first piece is crucial. Ensure there are no issues like missing, insufficient, excessive coating, or air bubbles. Devices or areas that must remain uncoated, such as connectors, should be free from paint, and coating thickness should be uniform before baking.

4. The working environment’s humidity should be controlled below 65% RH during the three-proof coating process. Since PCB, being a composite material, absorbs moisture, this can compromise the effectiveness of the three-proof paint. Therefore, the coating process should be conducted promptly after assembling the circuit board. If PCBA is stored for an extended period before coating, pre-baking at 60°C for 24 hours is recommended to ensure optimal results.