1: PCB Direct Plate-Making Method
Method: Apply a specific thickness of photosensitive paste (typically a diazonium salt-based paste) onto a properly stretched screen, then coat and dry it. Afterward, place a plate-making film onto the medium, expose it, develop, rinse, and dry to form a screen printing plate.
PCB Process: The preparation of photosensitive paste involves a series of steps: mesh cleaning, degreasing, drying, coating, drying again, exposure, development, drying, repairing, and final exposure. Each step plays a crucial role in the overall function and integrity of the screen mesh.
PCB Degreasing: A degreasing agent is used to eliminate grease from the screen. This ensures that the photosensitive paste bonds securely with the screen, making it resistant to peeling.
**Drying:** Dry the moisture to avoid mesh distortion, as excessive temperature can alter the tension. The drying temperature should be controlled between 40°C and 45°C.
**Preparation of Photosensitive Paper Pulp:** Mix the photosensitizer with purified water evenly, then allow the mixture to rest for 8 hours after preparation.
**Coating:** Use the gap to evenly apply the coating on the screen. The coating method can be either automatic or manual, depending on the situation. The number of coating layers should be determined based on the actual requirements.
When coating, first apply to the surface of the squeegee to fill the gaps in the mesh and avoid bubbles. Then, coat the printed surface (the side that contacts the PCB). For consistency, an automatic glue applicator should be used, applying an additional 3µm of film each time. The main focus for PCB welding net coating is:
– Coating the squeegee surface twice
– Drying
– Coating the printed surface three times
– Drying again
– Repeat drying and coating steps as needed, ensuring uniform drying.
**Coating Mistakes:**
1. **Correct squeegee surface:** Ensure the printing surface thickness is appropriate and meets specifications.
2. **Thin coating (printing surface):** Results in poor durability.
3. **Excessively thick coating on the squeegee surface:** When the photosensitive paste is too thick, the light exposure becomes uneven. During development, the ink from the rough surface may wash off, causing the film to detach and reducing the lifespan of the mesh.
4. **Too thin a coating on the squeegee surface:** Results in poor durability.
**Drying:** Ensure that the photosensitive paste dries uniformly. Prevent external drying from occurring before the internal moisture evaporates. Too high a temperature can cause the outer layer to dry too quickly, leaving moisture inside. After the screen is restored, maintain the temperature between 40°C and 45°C for approximately 10 minutes. Adjust drying time based on the film thickness.
**Exposure:** Proper exposure ensures the photosensitive paste hardens, creating a clear image on the substrate.
**Factors Affecting the Quality of the Screen:**
1. **Correct exposure energy:** Exposure time and vacuum pressure are critical factors.
2. **Cleaning the exposure machine’s glass:** Ensure the exposure glass is clean for optimal results.
Exposure energy is typically adjusted by altering exposure time. Production requirements should be based on the mesh count and the film’s layer thickness. Measurement tools should be used to determine the correct exposure time for different screen types.
Method: Apply a specific thickness of photosensitive paste (typically a diazonium salt-based paste) onto a properly stretched screen, then coat and dry it. Afterward, place a plate-making film onto the medium, expose it, develop, rinse, and dry to form a screen printing plate.
PCB Process: The preparation of photosensitive paste involves a series of steps: mesh cleaning, degreasing, drying, coating, drying again, exposure, development, drying, repairing, and final exposure. Each step plays a crucial role in the overall function and integrity of the screen mesh.
PCB Degreasing: A degreasing agent is used to eliminate grease from the screen. This ensures that the photosensitive paste bonds securely with the screen, making it resistant to peeling.
**Drying:** Dry the moisture to avoid mesh distortion, as excessive temperature can alter the tension. The drying temperature should be controlled between 40°C and 45°C.
**Preparation of Photosensitive Paper Pulp:** Mix the photosensitizer with purified water evenly, then allow the mixture to rest for 8 hours after preparation.
**Coating:** Use the gap to evenly apply the coating on the screen. The coating method can be either automatic or manual, depending on the situation. The number of coating layers should be determined based on the actual requirements.
When coating, first apply to the surface of the squeegee to fill the gaps in the mesh and avoid bubbles. Then, coat the printed surface (the side that contacts the PCB). For consistency, an automatic glue applicator should be used, applying an additional 3µm of film each time. The main focus for PCB welding net coating is:
– Coating the squeegee surface twice
– Drying
– Coating the printed surface three times
– Drying again
– Repeat drying and coating steps as needed, ensuring uniform drying.
**Coating Mistakes:**
1. **Correct squeegee surface:** Ensure the printing surface thickness is appropriate and meets specifications.
2. **Thin coating (printing surface):** Results in poor durability.
3. **Excessively thick coating on the squeegee surface:** When the photosensitive paste is too thick, the light exposure becomes uneven. During development, the ink from the rough surface may wash off, causing the film to detach and reducing the lifespan of the mesh.
4. **Too thin a coating on the squeegee surface:** Results in poor durability.
**Drying:** Ensure that the photosensitive paste dries uniformly. Prevent external drying from occurring before the internal moisture evaporates. Too high a temperature can cause the outer layer to dry too quickly, leaving moisture inside. After the screen is restored, maintain the temperature between 40°C and 45°C for approximately 10 minutes. Adjust drying time based on the film thickness.
**Exposure:** Proper exposure ensures the photosensitive paste hardens, creating a clear image on the substrate.
**Factors Affecting the Quality of the Screen:**
1. **Correct exposure energy:** Exposure time and vacuum pressure are critical factors.
2. **Cleaning the exposure machine’s glass:** Ensure the exposure glass is clean for optimal results.
Exposure energy is typically adjusted by altering exposure time. Production requirements should be based on the mesh count and the film’s layer thickness. Measurement tools should be used to determine the correct exposure time for different screen types.
