Monitoring methods for vacuum plating equipment
With the development of basic industry and high-tech products, the demand for high quality, high efficiency surface modification and coating technology extends to the depth. In the situation of mutual promotion of this field and related disciplines at home and abroad, surface modification and coating process simulation and performance prediction and other aspects have made breakthroughs. The following is an introduction to the monitoring method of vacuum electroplating equipment:
1. Visual monitoring: eye monitoring is used. During the growth of the film, due to the color change caused by the interference phenomenon, we control the film thickness according to the color change.
2, extreme monitoring method: when the film thickness increases, its reflectivity and penetration rate will follow the change, when the reflectivity or penetration rate to the extreme point, we can know the coating optical thickness ND is monitoring wavelength (into) a quarter of the integer multiple. However, the method of extreme value has a large error, because when the reflectivity or transmittance changes very slowly around the extreme value, that is, the film thickness ND increases a lot, R/T changes. The more sensitive position is at one eighth of the wavelength.
3. Fixed value monitoring method: this method USES the stop plating point not to monitor the quarter-wave level of the wavelength, and then the computer calculates the reflectivity of the total film thickness at a certain wavelength, which is the stop coating point.
4. Crystal oscillation monitoring: it works on the principle that the vibration frequency of quartz crystal is inversely proportional to its mass. However, one of the disadvantages of quartz monitoring is that when the film thickness increases to a certain thickness, the vibration frequency is not entirely due to the characteristics of quartz itself, which leads to a wired relationship between the thickness and frequency. In this case, new quartz oscillating plates must be used.