Tungsten Heater for Aluminizing – Large Area Film

Generally speaking, vacuum evaporation rate, uniformity, film thickness and vacuum evaporation are related to tungsten heater element shapes, sizes. The distance of the evaporation source and the workpiece is determined by vacuum evaporation degree and the required film thickness and other factors. When the evaporation distance is 6.5 cm, because of evaporation distance is short, the film will be uneven, and each screen can only be plated for one time, the working efficiency is not good enough, and it cannot meet the requirements of large-area screen. So the original 6.5 cm evaporation distance should be increased to 28 cm, and the diameter would be able to reach 26.5 cm, the evaporation of aluminum should be increased 6 points, the distance between each point can be controlled at 0.5 cm, each length of aluminum wire is 1.8 cm, diameter of tungsten heater is 0.7 mm with a total length of 15 cm. This can obtain large-area and uniformity film.

The thickness of the film can be controlled and measured with a film thickness measuring instrument and optical thin film controller. Both instruments can be used to measure the thickness of the film, but the measurement of optical thin film controller is more accurate. According to the test of tube, it is better to use a 50% transmissivity, which does not affect the incident electron energy, and it will not affect the resolution of the phosphor screen.

In addition, the coating vacuum chamber should be kept clean, after plating, it should be cleaned by absolute ethyl alcohol. Each parts of vacuum chamber should be ready for the next time. Operators should pay attention to the degree of vacuum coating whether it is stable or not. And select the appropriate evaporation rate when degree of vacuum reaches the requirement, the rate should be quick, which can form a well-distributed film with high quality.

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