Most traditional vacuum deposition tools use downstream pressure control to maintain pressure of gases in the vacuum chamber. The throttle valve set up can cost thousands of dollars. It also requires a separate control module to power the valve, provide PID data and set point functionality. The throttle valve setup can also cause delays when changing gasses or while waiting for the gas in the chamber to settle.
Placing a control instrument upstream of the chamber provides much faster response times and better stability using a fast-acting, proportional control valve. The upstream method also eliminates the need for additional valves, cutting equipment needs and set up cost. Alicat instruments offer this alternative.
The Alicat PC-EXTSEN
For larger scale or OEM projects, the Alicat PC-EXTSEN (external sensor) pressure controller is capable of controlling vacuum levels while mounted upstream from the chamber. This series is used when the process pressure is in high or ultra-high vacuum and requires an external gauge. The PC-EXTSEN takes an analog signal from the sensor and provides closed-loop control using a proportional valve.
By adding an external pressure sensor, it is possible to more accurately maintain the chamber pressure while also allowing the user to change or adjust the used gases independent of the vacuum deposition system as a whole. This allows for faster application of neutral gasses, improved control and steady pressure levels in the coating environment.
The PC-EXTSEN pressure controller provides power to the external vacuum gauge and is compatible with all gauge technologies, including ion, pirani and cold cathode as well as active or passive gauges and combination gauges.
The Alicat Integrated Vacuum Controllers (IVC)
For smaller experiments and projects where there isn’t an existing vacuum gauge, the Alicat IVC is the solution. Like the PC-EXTSEN, it cuts out the bulk, complication and expense of the traditional throttle valve pressure control method. The IVC includes a vacuum sensor integrated directly into the device, making it possible to control pressure in a vacuum chamber right out of the box. These sensors are capable of operating with high accuracy to low ranges, as low as 10 millitorr. The IVC also includes PID control directly from the device, and a pneumatically isolated sensor – ensuring higher accuracy compared to other solutions on the market – with precision measurement of the chamber and gas independence.
Placing pressure control devices upstream of the chamber in vacuum coating applications saves time, cost and increases accuracy in vacuum deposition tools.