What are the common defects in screen printing, and how to prevent and solve them?

Common screen printing defects include ink bleeding, uneven ink layer, pinholes, and poor adhesion. To prevent and solve these issues, targeted measures are needed. For ink bleeding, ensure the screen tension is uniform, optimize the ink viscosity (increase it appropriately), and adjust the scraper angle to avoid excessive pressure. For uneven ink layers, select screens with uniform mesh size, keep the scraper flat, and maintain a stable printing speed. For pinholes, thoroughly clean the screen and substrate to remove impurities, and filter the ink to eliminate air bubbles. For poor adhesion, pre-treat the substrate (such as plasma cleaning or primer coating) to improve surface wettability, and select inks that are compatible with the substrate.