The quality of PCB screen printing images and the film-forming state of the screen printing material are impacted by the performance of the printing material. Common faults caused by the printing material during the PCB screen printing process include:
- Hole plugging
- Contamination of the reverse side of the printed board by printing material
- Poor adhesion
- Sticking to the net
- Pinhole pitting
- Zigzag printed wires
- Silk screen pattern appearing on the screen printing pattern
- Spots
- Poor overprinting
- Bleeding and spreading of ink
- Uneven color of screen printing
To ensure quality screen printing and prevent these issues, it is essential to strengthen management and control of the screen printing process. Additionally, strict quality control on the printing materials is crucial. Various physical and chemical properties of the screen printed products must be tested. Factors such as corrosion resistance, bending resistance, solvent resistance, light resistance, weather resistance, viscosity, particle size, and bonding strength determine or directly affect the performance of printed boards.
To avoid screen printing issues, it is advised to: - Enhance management and control of the screen printing process
- Implement strict quality control of the printing materials
- Match the screen mesh number with the printing material used to avoid hole plugging
- Use appropriate printing material thinner and adjust viscosity to prevent drying and contamination
- Select printing materials that match the substrate to ensure good adhesion
- Avoid sticky net by considering pressure, temperature, and material characteristics
By following these guidelines and carrying out pre-test verifications, selecting suitable printing materials, and signing technical service agreements with manufacturers, the occurrence of poor screen printing can be minimized.