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Whether the ink quality of PCB circuit board is excellent is a comprehensive reflection


Whether the ink quality of PCB circuit board is excellent or not is absolutely the first thing to be considered. The scientific, progressiveness and environment-friendly formula are the comprehensive embodiment of excellent ink quality.

In the actual circuit board printing process, if the ink viscosity is high, it will cause printing leakage difficulties and serious sawtooth on the edge of the figure. In order to improve the printing effect, diluent will be added to make the viscosity meet the requirements. After in-depth study, it was found that ink viscosity is an important factor, but not the only one. There is another very important factor - thixotropy. It also affects the printing accuracy. Let's look at the relationship between each performance:

Viscosity is the abbreviation of dynamic viscosity. It is generally expressed by viscosity, that is, the shear stress of fluid flow divided by the velocity gradient in the direction of flow layer. The international unit is PA / S (Pa.s) or millipa / S (MPa. S). In PCB production, it refers to the fluidity of ink driven by external force.

Conversion relationship of viscosity unit:

1Pa。 S=10P=1000mPa。 S=1000CP=10dpa. s

Plasticity refers to the fact that after the ink is deformed by external force, it still maintains its properties before deformation. The plasticity of ink is conducive to improve the printing accuracy;

Thixotropic ink is colloidal when standing, and the viscosity changes when touched. It is also called shake and sagging resistance;

Fluidity (leveling) the extent to which the ink expands around under the action of external force. Fluidity is the reciprocal of viscosity. Fluidity is related to the plasticity and thixotropy of ink. The greater the plasticity and thixotropy, the greater the fluidity; If the mobility is large, the imprint is easy to expand. If the fluidity is small, it is easy to form a net and produce ink, also known as anilox;

Viscoelasticity refers to the ability of the ink to rebound quickly after being cut and broken by the scraper. It is required that the ink deformation speed is fast and the ink rebound is fast in order to be conducive to printing;

Dryness requires that the slower the ink dries on the screen, the better. After the ink is transferred to the substrate, the faster the better;

Fineness: the particle size of pigment and solid material, PCB ink is generally less than 10 μ m. The fineness shall be less than one third of the mesh opening;

Drawability when picking up ink with an ink shovel, the extent to which the filamentous ink does not break is called drawability. The ink is long, and there are many filaments on the ink surface and printing surface, which makes the substrate and printing plate dirty and even unable to print;

Transparency and hiding power of ink

For PCB ink, according to different uses and requirements, various requirements are also put forward for the transparency and hiding power of the ink. Generally speaking, circuit ink, conductive ink and character ink require high hiding power. The solder resist is more flexible.

Chemical resistance of ink

PCB ink has strict standards for acid, alkali, salt and solvent according to different purposes;

Physical resistance of ink

PCB ink must meet the requirements of external force scratch resistance, heat shock resistance, mechanical peeling resistance and various strict electrical performance requirements;

Safety and environmental protection of ink

PCB ink is required to be low toxicity, odorless, safe and environment-friendly.