Describe the characteristics of pcb circuit board solder resist ink

Today author from QiHe tvm802a mt pick and place machine sharing you with how to describe the characteristics of pcb circuit board solder resist ink

1. viscous and thixotropic

During the fabrication of printed circuit boards,
Screen printing is one of the indispensable important processes.
To achieve pictorial fidelity,
It is required that the ink must have good viscosity and suitable thixotropy.
Viscosity is the internal friction of a liquid.
It shows that under the effect of external force,
slide one layer of liquid over another,
The frictional force exerted by the inner layer of liquid.
The thick liquid inner layer encounters greater mechanical resistance when sliding,
Thinner fluids have less resistance.
The unit of viscosity measurement is poise.
In particular, it should be pointed out that temperature has a significant effect on viscosity.

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Thixotropy is a physical property of liquids,
That is, its viscosity decreases under stirring conditions,
After standing still, it quickly restores its original viscosity characteristics.
After stirring, the thixotropic effect lasts for a long time,
Enough to make its internal structure from scratch.
To achieve high quality screen printing effect,
The thixotropy of the ink is very important.
Especially during the scraping process, the ink is agitated, thus making it liquefied.
This effect speeds up the speed of the ink passing through the mesh, and promotes the even integration of the ink that was originally separated by the mesh line.
Once the scraper stops moving and the ink returns to a static state,
Its viscosity just returns to original required data very quickly again.

2. Precision:

Pigments and mineral fillers are generally solid,
After precision grinding,
Its particle size does not exceed 4/5 micron,
And form a homogeneous flow state in solid form.
Therefore, it is very important to require the ink to have precision.

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