INFICON MDC-360C Thin Film Deposition Controller - Manual (Page 126)

MDC-360C DEPOSITION CONTROLLER
SYSTEM INSTALLATION 9-2
Use a shutter to shield the sensor during initial soak periods to protect the crystal
from any sputtering that may occur. If a small droplet of molten material hits the
crystal, the crystal may be damaged and oscillation may cease.
9.3 SENSOR OSCILLATOR
The sensor oscillator, Figure 9-4, is designed to be used with industry standard 6
megahertz sensor crystals. The oscillator’s characteristics enable it to obtain
maximum life from the sensor crystal.
The oscillator is supplied with a 6” coaxial cable and a 10’ coaxial cable. The 6”
cable interconnects the oscillator and the feedthrough. The 10’ cable
interconnects the oscillator and the MDC-360C. This single coaxial cable
provides both power for the oscillator and the signal output for the controller.
Cables of any length are available upon request for replacing the 10’ cable. A
schematic of the oscillator is shown on Figure 9-3.
9.3.1 INSTALLATION
Connect one end of the 10-foot oscillator cable to the BNC connector on the
appropriate source-sensor board at the rear of the MDC-360C. Connect the other
end of the cable to the oscillator with the arrow pointed toward the sensor head.
The oscillator connects to the feedthrough leading into the vacuum chamber using
a 6 in. cable.
CAUTION: Always use the cables supplied by INFICON to make the
connections. Failure to make these connections properly will result in the
impedance mismatch of the oscillator circuit.
9.4 INSTRUMENTATION FEEDTHROUGH
A 1 inch diameter, O-Ring sealed feedthrough (IF-111, Figure 9-5) or a 2-3/4
inch Conflat® flange seal are available with 1/8 inch source and return water
cooling lines, and internal and external coaxial cable connectors. Base plate
thickness up to one inch can be accommodated.
RF interference and free electrons are effectively shielded from the signal
connector through the use of fully closed coaxial cable connections. A standard
coaxial cable with a Microdot® S-50 connector mates the internal feedthrough
connector to the sensor head. The feedthrough has a standard BNC connector for
the coaxial connection to the sensor oscillator.
9.5 SENSOR CRYSTAL REPLACEMENT
The Next Generation Cool Drawer™ simplifies the replacement of the sensor
crystal. However, since the system relies on the sensor crystal to perform
accurate measurements, care must be taken to maintain the cleanliness of the
crystal during installation. Please read the following Section 9.5.1 and 9.5.2
before attempting to replace the crystal.