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PCB Ink Quality Factors
Dec 22, 2018


Excellent PCB ink quality, is the comprehensive embodiment of the scientific formula, advanced and environmental protection.It is reflected in:

viscosity

Is short for dynamic viscosity. Generally expressed in viscosity, the shear stress divided by the flow direction of fluid flow velocity gradient, the international unit for Pa/S or mPa/S.In PCB production refers to the ink is driven by external forces produced by the flow.

Conversion relation of viscosity unit:

1Pa/S = 10P = 1000 mPa/S = 1000CP = 10dPa/S


Plasticity

Refers to the ink after deformation by external forces, still maintain its pre-deformation properties. The ink plasticity is conducive to improving the printing accuracy;


Thixotropic tropic

Ink is colloidal in static state, but its viscosity changes when touched, the property also known as rolling degeneration, flow resistance;


Liquidity

(Fluidity) the extent to which ink expands in all directions under external forces. Fluidity is the reciprocal of viscosity, fluidity is raltated with ink plastic and thixotropy. Large plasticity and thixotropy, greater fluidity;Large fluidity, the imprinting is easy to expand. Fluidity is small, easy to appear knot net, produce knot ink phenomenon, also call net grain;


Viscoelastic

Refers to the ink after scratched by scraper, the performance of quickly rebound for the ink shear fracture. Require fast ink deformation speed, quickly ink rebound facilitate printing;


Dry

Requires the ink on the screen drying as slowly as possible, and hope that the ink transfer to the substrate, the faster the better;


Fineness

Pigment and solid particle size, PCB ink generally less than 10 microns, fineness should be less than one third of the mesh opening;


Drawing sex

When picking up ink with an ink spatula, the extent to which the filamentous ink does not break is called wiredrawing. Long ink filament, in the ink surface and printing surface will appear a lot of fine wire, making the substrate and printing plate stained, or even unable to print;


Ink transparency and hiding power

For PCB ink, according to the different of the use and requirements, the ink transparency and hiding power also put forward a variety of requirements.In general, line ink, conductive ink and character ink, are required to have a high hiding power. While solder resistors are more flexible.


Chemical resistance of ink

According to the different purposes of use, the requirements of acid, alkali, salt and solvent requirements for PCB ink have strict standards;


Physical resistance of ink

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


Ink use safety and environmental protection

PCB ink requires low toxicity, no odour, safety and environmental protection.


The above summarizes 12 basic properties of PCB inks, and in the actual process of screen printing, and the operator is closely related to the viscosity problem.


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