Discussion on the important technical performance

2022-10-23
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On the important technical performance of PCB ink

whether the quality of PCB ink is excellent, in principle, it is impossible to separate from the combination of the above major components. Excellent ink quality is the comprehensive embodiment of the scientific, progressiveness and environmental protection of the formula. It is reflected in: viscosity

is the abbreviation of DynamicViscosity. It is generally expressed by viscosity, that is, the shear stress of fluid flow divided by the velocity gradient in the direction of the flow layer, and 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 forces

conversion relationship of viscosity units:

1pa. S=10p=1000m, with broad market prospect PA. s=1000cp=10dpa. S

plasticity

refers to the fact that the ink retains its properties before deformation after deformation under external force. The plasticity of ink is conducive to improving the printing accuracy

thixotropic

a property in which the ink is colloidal when standing, and the viscosity changes when being touched, also known as shake, which is expected to increase to $12.12 billion in anti sagging property

fluidity

(leveling) the extent to which the ink expands around under the action of external force. Fluidity is the reciprocal of viscosity, which is related to the plasticity and thixotropy of ink. The greater the plasticity and thixotropy, the greater the fluidity; If the liquidity is large, the imprint is easy to expand. Those with small fluidity are prone to knot and ink deposition, also known as veins

viscoelasticity

refers to the performance that the ink sheared and broken quickly rebounds after the ink is scratched by the scraper to support the development of the company with practical actions. It is required that the ink deformation speed is fast and the ink rebound is fast, which is conducive to printing

dryness

requires that the slower the ink dries on the plate, the better, and that the faster the ink is transferred to the substrate, the better

fineness

the particle size of pigments and solid materials, PCB ink is generally less than 10 m, and the fineness should be less than one third of the hole opening

drawability

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

transparency and hiding power of inks

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

chemical resistance of inks

pcb inks have strict requirements for acids, bases, salts and solvents 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 printing ink

pcb printing ink requires low toxicity, odorless, safe and environmental protection

above, we have summarized the basic properties of twelve PCB inks, among which the viscosity problem is closely related to the operator in the actual operation of printing. The level of viscosity has a great relationship with the smoothness of silk screen printing. Therefore, in PCB ink technical documents and QC reports, the viscosity is clearly marked, indicating under what conditions, what type of viscosity testing instrument to use, etc. In the actual printing process, if the ink viscosity is high, it will cause printing leakage difficulties and serious jagged edges. In order to improve the printing effect, diluent will be added to make the viscosity meet the requirements. But it is not difficult to find that in many cases, in order to obtain the ideal resolution (resolution), no matter what viscosity you use, it is always impossible to achieve. Why? After in-depth study, it was found that ink viscosity is an important factor, but not the only one. There is another quite important factor, thixotropy. It also affects the printing accuracy

it is still in the period of strategic opportunity

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