The final stage of surface preparationa - clearing of products surface by ions stream by means of accelerators with an anode layer.
Products install on trays on 15 pieces on everyone and are loaded into the chamber, then the chamber pressurized. Then make spilling of chambers up to demanded pressure. Spilling time of the chambers is 7 minutes, time of surface clearing 3,5 minutes. After the final stage of surface preparation there is a process of covering deposition on products. Time of covering deposition makes 3,5 minutes.
After processing of batch workpieces the chamber will depressurize and make an unloading of details. Further carry out quality control of the covering: if the product meets the requirements of the customer, it is classified as suitable if is not present - rejected. The covering of the products mismatching requirements on quality, leaves, and the detail passes repeated processing.
Problem of vacuum evaporation almost in all cases is sedimentation films with the set parameters. If external parameters of films, such as their thickness or superficial resistance are most important enough to define the moment of time when this parameter will reach necessary value, and to stop process of evaporation. However internal parameters of film, such as: the density, specific resistance, a mechanical stress, crystallization degree, - depend on sizes of evaporated substance stream and molecules of residual gas which get on the substrate. Hence, often it is necessary to support the certain speed of sedimentation. Devices by means of which spend measurements during evaporation, share on two categories: sensors of thickness and sensors of evaporation speed, For definition of the evaporated substance stream density, quantity of the besieged weight or the parameters depending on thickness of the film, the various physical phenomena are used.
During clearing of products surface before deposition of covering it is necessary to supervise working pressure, density of an ionic current upon the details surface.
For pressure measurement in range from 1 mm hg up to 10- 3 mm the thermocouple vacuum gage of type ВТ-2А [7] which represents the device consisting from thermocouple manometer, the measuring block including the scheme for the heaters of the thermocouple feed and pointer indicator, measuring thermo electromotive of the thermocouples is used. .
The electromotive power of the thermocouple is defined by temperature of the heater. If in the thermocouple, connected it is vacuum-dense with the surveyed volume, a heater current to maintain constants, emf of thermocouples will be defined by pressure of surrounding gas since change of temperature of a heater will be determined by heat conductivity of surrounding gas. Hence, at pressure decline heat conductivity of gas will decrease, the temperature of a heater will increase, will increase and emf of thermocouples. If dependence of size of thermo electromotive force is known. From pressure, the device measuring thermo electromotive of thermocouples, can be calibrated not in millivolts, and directly in terms, measuring size of pressure, i.e. in millimeters of a mercury column.
For the control of pressure over range from 10-4 up to 10-13 mm the vacuum gauge of inversely-magnetron type ВИМ-2А [8] is used. The vacuum gauge contains electric installation (consisting of measuring and remote blocks) and inversely-magnetron manometrical converter MM-14M. Electric installation provides measurement of a digit current of the converter, its feed, warming up of the anode by gating of current and warming up of the cathode by electronic bombardment.
There are two methods of measurement of sprayed substance stream density. The first method is based on ionization of sprayed atoms by electrons and registration of an ionic current. Other method is based on measurement of dynamic force from which particles colliding with surface influence it. For reception of film thickness it is necessary to integrate data on dispersion speed. In both methods of measurements empirical calibration, i.e. definition by independent way of thickness of the film received for known time of sedimentation, with the purpose of calibration in absolute sizes of instrument readings is required. Received calibration curve may be used only for the given gauge and the given evaporated substance. Reproducibility of the given curve depends also on that, mutual positions of the evaporator, the gauge and a substrate are how much fixed.
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