Basic Steps Of Vacuum PVD Coating Process

- Apr 11, 2018-

Pretreatment process

Decoating, blasting, polishing, passivating, cleaning, clamping

Coating process

Evacuation, heating, leak rate test, bombardment cleaning, coating, cooling out


1. Cleaning: Ensure that the surface of the product before coating is clean, the cleaner the surface, the better the coating quality can be guaranteed.

2. Evacuation: Evacuated the residual gas from the vacuum chamber.

3. Heating: The furnace and workpiece are heated at the same time to accelerate the release of residual gas.

4. Voltage rise rate test: Gas leakage rate and gas release rate of the test furnace.

5. Bombardment cleaning: Remove impurities from the surface of the workpiece to expose the clean surface.

6. Coating: Deposited film.

7. Cooling: Avoid oxidation and discoloration of the workpiece.

Why cooling it?

After the coating process is completed, the temperature of the vacuum chamber is up to 500°C.  If it is evacuated without cooling, the surface of the high-temperature workpiece that is not plated will become blue because of the reaction with the air.

How to cooling?

1. To close the high valve and vacuum gauge, and the vacuum chamber is separated from pump group.

2. When the operator presses the N2 vent button, the pre connected nitrogen will be filled into the vacuum chamber through the N2 inflation valve, and when the pressure in the vacuum chamber reaches the preset pressure of the pressure switch, the N2 inflation valve is closed.

3. The vacuum chamber is filled with a large amount of N2, and the vacuum degree is very low, which is more conducive to heat conduction. It can shorten the cooling time and increase the production efficiency, and the actual cooling time can be reduced from 90 minutes to 60 minutes.

4. Because helium has higher thermal conductivity, the cooling of helium is faster than nitrogen, but the cost is higher.

5. The rapid cooling program for foreign equipment can shorten the cooling time by 50% through cooling the cooling cycle of the gas.

The reasons for the pressure rise test

Vacuum environment is the most important factor affecting the final coating quality. Before the coating, the pressure rise rate must be performed to ensure that the vacuum environment conditions meet the coating standard.