The vacuum
coating machine has a
component called cryogenic trapping pump. If the general professional vacuum
coating personnel don't mention this component, many people almost don't know
such a component. So what role does cryogenic trapping pump play in the vacuum
coating machine? The following is vacuum series to introduce the application
principle of the cryogenic trapping pump of the vacuum coating machine, hoping
to help everyone:
In the high
vacuum environment, there are some residual gases. Because the molecular weight
of water molecules is smaller than that of oxygen, nitrogen and other main air
components, neither oil diffusion pump nor molecular pump can pump them out
quickly and effectively, so they accumulate more and more, and finally become
residual gas accounting for more than 65%~95% of residual gas;
Meanwhile, due
to the inevitable evaporation of pump oil during the use of the vacuum pump, a
small amount of oil vapor will enter the vacuum system. Due to the existence of
water vapor and oil vapor, the vacuum system can't reach the vacuum degree
required by customers quickly, which leads to longer vacuumizing time and lower
production efficiency. The higher the required vacuum degree, the higher the
environmental humidity, and the more obvious the influence.
At the same
time, the existence of water vapor and oil vapor will lead to the decrease of
film firmness, failure of multilayer coating and uneven color.
Under certain
conditions, water vapor will ionize to generate oxygen, which will oxidize the
target and cause the color of the coating to change. The higher the
environmental humidity, the higher the temperature, the higher the required
vacuum degree and the greater the influence. Therefore, water vapor and oil
vapor are the main harmful gases in the field of vacuum coating machine and high vacuum obtaining.
The function of cryogenic trapping pump is to trap residual gas, which
effectively solves the problem of difficult extraction and slow speed in high
vacuum state, and improves the use efficiency of vacuum system. The working
principle of cryogenic pump is: place a refrigeration coil which can reach
below -120℃ in the vacuum chamber or
the pump port of oil diffusion pump, and quickly trap the residual gas of
vacuum system through the low temperature condensation effect on its surface.
Thereby greatly shortening the vacuumizing time (which can shorten the pumping
time by 60-90%) and obtaining a clean vacuum environment (which can improve the
vacuum degree by half an order of magnitude to 10 Torr and 10 Pa).
