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Discussion on technical performance of circuit board PCB ink
PCB ink quality is excellent, in principle, can not be separated from the combination of the above components. Ink quality is excellent, is the formulation of scientific, advanced and environmental protection of the comprehensive embodiment. Embodied in:
It is the abbreviation of dynamic viscosity (DynamicViscosity). In general, the shear stress in fluid flow is divided by the velocity gradient in the direction of the flow layer, and the international unit is viscosity / S (Pa. S) or mPa per second. S). In PCB production, the ink is driven by external force to produce liquidity.
A unit of viscosity:
1Pa. S=10P=1000mPa. S=1000CP=10dpa.s
Refers to the ink after the deformation of the external force, but still maintain its deformation before the nature. The plasticity of the ink helps to improve the printing accuracy;
Ink in the static when it is colloidal, and touched by changes in viscosity of a nature, also known as shaking, resistance to flow resistance;
(levelling) the extent to which ink is applied to the periphery under the action of an external force. Fluidity is the reciprocal of viscosity and fluidity is related to the plasticity and thixotropy of the ink. Plasticity and thixotropy are large, liquidity is large; liquid imprinting is easy to expand. The mobility of small, easy networking, produce ink phenomenon, also known as the;
Refers to the ink in the scraper after scraping, the shear fracture of the ink, rapid rebound performance. Requirements of ink deformation speed, ink rebound quickly, in order to facilitate printing;
Require ink on the screen of drying the slower the better, and want to transfer ink to the substrate, the sooner the better;
The size of pigment and solid particles, PCB ink is generally less than 10 m, the size of fineness should be less than 1/3 of the opening of the mesh;
When an ink spatula is used to lift the ink, the extent to which the filamentary ink does not break is called wire drawing. "Long, a lot of filaments found in oil and some printing surface of the substrate, and a printing plate dirty, even unable to print;
The transparency and hiding power of ink
For PCB ink, according to the use and requirements of different, for ink transparency and hiding power also put forward various requirements. In general, line inks, conductive inks, and character inks require high hiding power. The solder resist is more flexible.
Chemical resistance of printing ink
PCB ink according to the purpose of the use of different requirements of the acid, alkali, salt and solvent requirements are strict standards;
Physical properties of inks
PCB ink must be resistant to external force, scratch, heat shock, mechanical stripping, and to achieve a variety of stringent electrical performance requirements;
The use of ink, safety and environmental protection
PCB ink requires low toxicity, no odor, safety and environmental protection.
Above, we summed up the basic properties of twelve PCB ink, and in which the actual operation of the screen printing, and the operator is closely related to the viscosity problem. The viscosity of the level on the screen smoothly or not, great relationship. Therefore, in the PCB ink technical documentation and QC reports, viscosity is clearly marked, indicating what conditions, what type of viscosity testing instruments. In the actual printing process, if the ink viscosity is too high, will cause the printing difficulties, graphics zigzag serious, in order to improve the printing effect, will join the diluent, the viscosity reached the requirements. But it is not difficult to find, in many occasions, in order to obtain the ideal resolution (resolution), whether you are using what the viscosity can not realize. Why? After in-depth study, it was found that the viscosity of the ink is an important factor, but not the only. There is another quite important factor, thixotropy. It is also affecting printing accuracy.
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