Electron Beam Evaporation Vacuum Coating Machine Principles and Characteristics

Electron Beam Evaporation Vacuum Coating Machine Working Theory

Electron beam evaporation source is heated by hot cathode emits electrons in the electric field, a high energy density electron beam directly onto the coating material bombardment. Kinetic energy of the electron beam is converted to heat, so that the material is heated to be gasified, complete evaporation coating.

The kinetic energy of electrons in the electric field potential U, obtained was
The kinetic energy of electrons in the electric field potential U, obtained
 In the formula, (electron charge to mass ratio). If the flow rate of the electron beam of electrons ne, the thermal effect is generated electron beams Qe

 Qe = neeUt = IUt

 Where

       I- beam electron beam, A;

       t- beam current duration of action, s;

      U- potential difference, V.

When the potential difference generated by the thermal energy (acceleration voltage) is high, the formula (Qe = neeUt = IUt) can make the membrane vaporized, thereby providing a good source for vacuum coating technology.

 Electron beam heating evaporation advantages:

① electron beam heating than resistance heating has a higher energy density, high melting point materials can be evaporated, such as W, Mo, Al2O3, etc., and to obtain a higher evaporation rate;

② vaporized materials into the water-cooled copper crucible, to avoid contamination of the crucible material, a thin film of high purity can be prepared;

③ particle kinetic energy electron beam evaporation, is favorable for obtaining a dense, good film adhesion.

 Electron beam heating of disadvantages:

① structure is more complex, more expensive equipment;

② If the high vapor density near the evaporation source, the interaction between the electron beam occurs and vapor particles, electron energy loss and the track will be offset. While causing excitation and ionization vapor and residual gas will affect the film quality.