News centres

Home > News > Industry Trends > How does the electron gun sparking problem of optical pvd coating machine occur?

How does the electron gun sparking problem of optical pvd coating machine occur?



When coating engineers operate optical pvd coating machines, the electron gun often sparks. Engineers who are not particularly skilled in coating technology and equipment may be very distressed by this phenomenon, because the electron gun sparks can cause The probability of good workpieces is reduced, so coating engineers pay special attention to the phenomenon of electronic flashing in optical pvd coating machines. What causes the phenomenon of electronic flashing? Below, the editor of Huicheng Vacuum will introduce it to you in detail, hoping to help everyone. :

optical pvd coating machines

When the electron gun is evaporating, ions generated by the collision of electrons in the electron beam with gas molecules and vapor of the evaporated material bombard the negatively charged high-voltage electrode and its lead, causing sparking. In addition, if there are dust particles and other debris in these parts with negative high voltage, the electric field will be concentrated there and it will easily cause ignition. Therefore, the high-voltage power supply of electron beam evaporation equipment is equipped with a high-voltage automatic arc extinguishing reset device. When sparking is very serious, the high voltage will be automatically cut off and then automatically restored. The shorter the time between cutting off and restoring, the less it will affect evaporation. Craftsmanship.
In addition, in order to reduce the number of sparks, the following points should be paid attention to during installation and use:
1. The high-voltage lead should be as short as possible and shielded with a well-grounded stainless steel plate. Do not bend the lead here and there in pursuit of beauty.
2. The metal parts and leads of the gun head should be polished regularly with fine sandpaper, and then cleaned with acetone. Use a tap to tap the screw hole of the upper screw regularly to make it easier for the screw to go up and down and ensure that it is pressed tightly.
3. All ceramic parts should be replaced after being contaminated.
4. The electronic gun body should be reliably grounded.
5. Materials with a large amount of outgassing should be fully preheated to completely degas. The power during evaporation must be appropriate and should not be too high to cause material splashing.
6. The connection between high-voltage feeders and high-voltage insulator metal parts must be reliable and checked frequently to avoid increasing contact resistance and causing heat and burnout.
7. The evaporation baffle should be 70mm higher than the evaporation source.
The problem of electronic flashing of optical pvd coating machines must be minimized during installation and use, so as to reduce unnecessary waste and control coating costs.