Large Single Heavy Tungsten Plate Target Manufacturing Key Points

The large single heavy tungsten plate tungsten target material is mainly used for the coating of the photovoltaic element substrate. The tungsten plate used in this field has a large size, the weight of the single plate is 80 to 150 kilograms, and it has the characteristics of high temperature resistance and good compactness.

The physical properties of the product itself directly affect the performance of the coating. In the process of coating, the gas suddenly released in the pores inside the target, resulting in the splash of large size target particles, or after the film is formed by two electron bombardment, and the appearance of these particles will occur. To reduce the quality of film, in order to reduce the porosity in target solids and improve the performance of thin films, target density is generally required.

As the target atoms are easily sputter along the most closely aligned direction of the six atoms, the sputtering rate is increased by changing the crystal structure of the target, and the crystallization direction of the target is greatly influenced by the thickness uniformity of the sputtering coating. The material structure is very important to the sputtering process of the film.

In order to produce large single tungsten plates with high quality and quantity, the purity of tungsten powder should be more than 99.95%, and the particle size should be between 2.4 and 3.2μm.

(1) The solid powder tungsten slab was prepared by loading the raw material into the rubber mold sleeve, and then the cold isostatic press was used. The pressure was 300 to 400Mpa, and the solid slab was formed after 8 to 10 minutes.

(2) The solid slab after forming is put into the medium frequency sintering furnace, and the heating temperature is 2300°C, the heating time is 28 hours, then the water cycle cool down for 9 hours to the room temperature, the forming body is spare.

(3) The processed slab is heated to 1300 - 1400°C and the heating time is 2-3 hours.

(4) The treated tungsten plate was cleaned by 25% to 40% sodium hydroxide solution and then cut into the required size.

Through the above process, the tungsten plate targets have better compactness and relative density up to 99.95%. At the same time, the tungsten plate is recrystallized in the two high temperature environment, the grain size is refined, the grain size is reduced from millimeter to micron grade, and the grain structure is optimized. When the product is coated with LED, the uniformity of the film and the quality of the wiring are large. The large scale improvement has achieved low cost and high efficiency, meeting the new requirements of solar PV products for specific impedance and membrane stress. 

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