The cathode target temperature of vacuum coating machine has a great influence on arc, and whether the temperature control is timely and reasonable directly affects the coating effect of substrate and the excellent product rate. Therefore, when operating vacuum coating machine, general manufacturers will invite professional coating engineers who have experience in coating technology, which can not only control the cost, but also improve the efficiency. What are the effects of cathode target temperature of vacuum coater on arc?

The stability of cathode arc discharge combustion of target source depends on the evaporation temperature of cathode surface. Lowering the cathode surface temperature will bring high arc combustion stability. At the same time, reducing the temperature of the cathode evaporation surface will also lead to a decrease in the number of large particles and large sputters in the metal vapor.

Observing the combustion of cathode arc of vacuum coating machine, it is always found that the arc spot is very rough before the arc goes out. Sometimes, there are even clumps of arc spots. After extinguishing, it was observed that the target surface was red and the target surface temperature was very high. The appearance of rough arc spot makes the arc current more concentrated on the target surface, which leads to over-concentration of spot current on the target surface under the arc spot, which makes the target surface temperature under the arc spot higher and produces a lot of thermionic emission. As a result of a large amount of thermionic emission on the target surface, on the one hand, a large amount of space charges are neutralized, which makes the electric field on the cathode surface become a deceleration field, and even causes the electric field on the cathode surface to be equal to zero. On the other hand, a large amount of thermionic emission has a considerable cooling effect on the cathode surface. As a result, there is neither strong electric field generated by space charge to maintain surface emission nor extremely high surface temperature to generate thermionic emission, which leads to arc extinction.

Therefore, in the design of multi-arc target source of vacuum coating machine, attention should be paid to fully cooling the cathode target, and direct water cooling is preferred. When indirect water cooling is adopted, materials with good thermal conductivity (such as copper, aluminum, etc.) should be selected for adjacent parts such as cathode base.