March 22, 2021
PCB is an important electronic component, the support of electronic components, the carrier of electrical connection of electronic components. PCB circuit board needs screen printing in the process of production. What are the solutions to common problems in screen printing of PCB circuit board?
Screen ink leakage
In screen printing, the material on the screen drips onto the printed board. The reasons for this failure are: dust, sundries on the surface of PCB or in the printing material, damage of screen plate caused by scraper pressure, dust or sundries during screen printing; in addition, inadequate exposure of screen mask glue during plate making may result in incomplete curing of screen mask and small holes formed during screen printing, resulting in ink leakage. In this regard, adhesive paper or tape can be used to paste on the hole of the screen, or can be used to repair the screen.
Damage and Accuracy Decline of Screen Plate
After a long period of use, due to the abrasion of the scraper and the influence of printing, the accuracy of the screen will gradually decrease or be damaged even if the quality of the screen is very good. This is determined by the lifetime of the screen. The number of times (or the length of service life) of screen printing is closely related to the way of mask making. The service life of direct screen printing is longer than that of indirect screen printing.
Faults caused by overprinting
In screen printing, the force applied to the scraper produces the impression. The purpose is to make the screen and the printed board in line contact, and the scraper scratches the printing material through the screen to form an image. The size of the press depends on the tension of the screen, the length of the scraper, and the distance between the screen and the PCB.
The high pressure of scraper will not only make the printing material pass through a large amount, but also cause the bending deformation of scraper. On the contrary, it will reduce the printing material pass through, and even make the screen plate and the printed board not be in line contact and become surface contact. Not only can not screen print a clear image, but also can cause scraper wear and screen mask falling off, screen stretching, image deformation.
Above is SEPRAYS fully automatic PCB sub-board machine for you to introduce the PCB circuit board screen printing common problems of solution analysis, I hope to provide you with a reference. There are different opinions can also contact Zhimao sub-board machine, to discuss together oh!
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