Screen Printing Quality: Key Influencing Factors
1.1 Material Properties: Viscosity, Fineness, and Fluidity
1.2 Screen Conditions: Mesh, Tension, and Photosensitive Adhesive
1.3 Printing Parameters: Pressure, Blade Hardness, Angle, and Speed
1.4 Printing Environment: Temperature, Humidity, and Cleanliness
Viscosity and Printability of Materials
The composition of printing materials, such as synthetic resins and pigments, can be affected by temperature, subsequently altering their viscosity. Maintaining constant temperature and humidity in the screen printing room along with standardized screen plate and PCB screen printing conditions can lead to stable quality.
Fluidity and Screen Printing
Particle size and agglomeration in the printing material dictate mesh selection for optimal fluidity. For instance, the mesh opening should be 3 to 5 times the average particle size for effective printing.
Material Fluidity and Printing
Before using stored printing materials, stirring is essential as pigment particles may agglomerate over time. Thixotropic fluids, which decrease in viscosity with increased shear rate, require time for recovery after stirring. The proper time factor and viscosity index, represented by the thixotropic index (TI), play critical roles in determining print pressure, wire resolution, and leveling performance.

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