Screen printing design is a critical step in PCB manufacturing that directly affects print quality and production efficiency. This article will provide a detailed overview of the specific processes involved in two key stages: screen preparation and screen drying.
I. Screen Printing
Screen drawing is the process of creating screen printing stencils, which are used to apply printing ink or solder paste to a PCB.
1. Clean the mesh frame
First, clean the mesh frame to remove any residual adhesive, screen mesh, and other debris to ensure proper adhesion between the screen mesh and the frame.
2. Horizontal Calibration
Place the mesh frame on the platform and make sure it is not warped.
3. Adhesive Layer
Apply a thin, even layer of Nanbao heavy grease to the bonding surface between the undeformed screen frame and the mesh to enhance the adhesion between the mesh and the screen frame after stretching.
4. Casting a Net
Place the mesh evenly between the clamps, then pull it taut; this usually requires several pulls to achieve the desired tension.
5. Applying Adhesive
Use a small brush to apply the glue evenly to the joint between the frame and the mesh.
6. Apply the edge banding
Use a squeegee to press the remaining seam onto the adhesive-coated surface, ensuring the integrity of the mesh.
7. Putaway
Finally, store the finished screen stencil for future use.
II. Mesh Drying
Screen drying is a step used to clean and prepare screen printing stencils.
1. Wash the net
Use a polishing compound to remove grease, patterns, and blue oil, then rinse the screens with a high-pressure water jet to ensure they are clean.
2. Barbecue
Place the wire mesh mold in the oven and heat it, typically at a temperature below 48°C.
3. Protective Film
After cleaning the screen, apply a water-based coating or a adhesive film, and then apply the appropriate ink to the stencil.
4. Using Templates
Let the stencil dry, then use it to print the corresponding design.
5. Selection of Netting
Use the appropriate type of screen mesh, as well as green ink, undercoat, topcoat, and other inks.
6. Screen Protector Application Line
Apply the film using a water film or a film application line, and apply the appropriate ink.
7. Exposure
Use an exposure unit to expose the printing stencil in order to set the ink.
8. Rinse and Inspect
Rinse the screen, check the print quality, and correct any defects.
Conclusion
These are general steps for PCB screen printing design. However, the specific steps and requirements may vary depending on the type of PCB and the manufacturing process. Be sure to follow the specifications and standards for PCB manufacturing to ensure the quality of the final PCB.
