PCB News - On HDI circuit board ink performance and ink color classification

On HDI circuit board ink performance and ink color classification

Ink is an indispensable raw material for HDI circuit boards/blind-hole boards/buried-hole boards. It mainly protects the circuit board, protects the copper skin from oxidation, insulation and so on. Whether the quality of HDI circuit board/blind-hole board/buried-hole board ink is excellent is reflected in its own viscosity. The English is: viscosity, that is, the shear stress of the flow divided by the velocity gradient in the direction of the flow layer, and the unit is Pa/sec.
Plasticity: refers to the performance of the ink to maintain its previous shape after being subjected to external forces. Plasticity can improve the printing accuracy of the ink.
Thixotropy: The ink is gelatinous when no external force is received, and then becomes another shape after being forced.
Dryness: If the ink dries as slowly as possible, it is hoped that the faster the ink transfer to the substrate, the better.

Hiding power: For /////HDI circuit board/blind hole board/buried hole board ink, according to special purpose and requirements, higher hiding power is required.
Viscoelasticity: refers to the ability of the ink to rebound quickly after being cut by the squeegee. The better the elasticity of the ink is, the better it is for printing.
Fluidity: Fluidity means that the ink flows around under external force, especially gravity. It is the reciprocal of the viscosity. The plasticity and thixotropy are large, and the fluidity is large.
Roughness: When scooping up the ink with an ink shovel, a non-broken filament will become a wire drawing. The longer the wire drawing, there will be a lot of filaments on the HDI circuit board, which cannot be printed.
After the ink is used, it must be resistant to external scratches, heat shock, mechanical peeling, and so on. And to comply with PCB international use safety performance and environmental protection performance.
Commonly used ink colors for HDI circuit boards:
The most common ink color is generally green, and HDI circuit boards/blind-hole boards/buried-hole boards are generally required to be photosensitive/matte green ink. Some other commonly used colors are: black, white, yellow, red, blue, etc.