What are the Common Faults of PCB Circuit Board Screen Printing?
PCB screen printing is an important part of the PCB manufacturing process. So, what are the common faults of PCB circuit board screen printing? Let’s first introduce the faults at the screen level.
Failure at the screen level
1. PCB hole is blocked
The reasons for this kind of situation are: the printing material dries too fast, the screen is dried up and the holes are blocked, the printing speed is too fast, and the squeegee strength is too high. The solution is to use organic solvents with slow volatiles to adjust the printing material, and lightly clean the screen with a soft cloth dipped in organic solvents.
2. PCB screen ink leakage
The reasons for this type of failure are: floating dust and dirt in the surface of the PCB or printed materials, which damage the screen during screen printing; in addition, the screen mask glue is not exposed enough during printing and making, which leads to the drying of the screen mask. Incomplete solidification causes ink leakage. The solution is to use tape or tape to stick on the small round holes of the screen, or repair it with screen glue.
3. Damage and reduction of precision of the circuit board screen
Even a very good quality screen, after long-term application, its precision will gradually decrease or be damaged due to damage caused by scraping and printing pressure. The service life of the immediate legal screen is longer than that of the indirect legal screen. Generally speaking, the immediate legal screen is used for mass production.
4. Failure caused by excessive printing pressure
If the pressure of the squeegee is too large, it will not only cause a large amount of printing material to pass, and cause the squeegee to bend and deform, but it will cause a small amount of printing material to pass, and it will not be able to print a clear image on the screen. It will also continue to cause damage to the squeegee and the screen mask to fall off. The wire mesh becomes longer and the image is distorted.