Coating power supply in vacuum coating (magnetron sputtering), why is pulse bias power supply better than DC power supply?

Coating power supply in vacuum coating (magnetron sputtering), why is pulse bias power supply better than DC power supply?

Vacuum coating A technique for producing thin film materials by physical means. In the vacuum chamber atoms of the material are isolated from the heating source and hit onto the surface of the plated object. The technology was first used to produce optical lenses, such as those for nautical telescopes. After extension to other functions of film, record aluminum plating, decorative coating and material surface modification. Such as watch case plating gold, mechanical tool coating, change the processing of red hard.

The film layer is prepared in vacuum, including crystalline metal, semiconductor, insulator and other elemental or compound film. Although chemical vapor deposition also uses vacuum means such as reduced pressure, low pressure or plasma, but generally vacuum coating refers to the deposition of thin films by physical methods. Vacuum coating has three forms, namely evaporation coating, sputtering coating and ion plating.

Vacuum coating technology first appeared in the 1930s, 1940s and 1950s began to appear in industrial application, industrial mass production began in the 1980s, in electronics, aerospace, packaging, decoration, bronzing printing and other industries have been widely used. Vacuum coating refers to the vacuum environment, a metal or metal compound in the form of vapor deposition to the material surface (usually nonmetallic materials), belongs to the physical vapor deposition process. Because the coating is often a metal film, it is also called vacuum metallization. The generalized vacuum coating also includes non-metallic functional films, such as polymer, that are vacuumized on the surface of metallic or non-metallic materials. In all the coated materials, plastic is the most common, followed by paper coating. Compared with metal, ceramic, wood and other materials, plastic has the advantages of sufficient sources, easy to control the performance, convenient processing and so on. Therefore, a wide variety of plastic or other polymer materials as engineering decorative structural materials are widely used in automotive, household appliances, daily packaging, process decoration and other industrial fields. But the plastic material is surface hardness is not high, not enough gorgeous appearance and low wear resistance of defects, such as the plastic surface evaporation, a thin layer of metal film, can give the appearance of plastic Alfred metal, suitable metal source also can greatly increase the surface wear resistance, greatly broaden the plastic decorative and application scope.

The function of vacuum coating is various, which also determines its application is very rich. In general, the main functions of vacuum coating include giving the surface of the plated parts a high degree of metallic luster and mirror effect, making the film layer has excellent barrier performance on the film material, providing excellent electromagnetic shielding and conductive effect.