INFICON STC-2000A Thin Film Deposition Controller Operating Manual - Manual (Page 34)

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STC-2000A DEPOSITION CONTROLLER
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Sensor head hardware generalizations (see Section 4 for actual installation details):
A vacuum chamber usually has a number of ports with flanges allowing access to the chamber interior.
A typical vacuum feedthrough is a threaded cylindrical piece of metal that fits into a chamber's flange (has
the appearance of a large bolt with nut and washer). A vacuum feedthrough can provide for the passage of
water pipes, compressed air and the electrical connection to the crystal through the chamber wall (or floor)
without leaking under vacuum. The vacuum feedthrough typically has relatively short lengths of pipes
passing through it from end to end, an electrical passthrough consisting of a microdot connector on the
interior side (for the crystal connection) and a BNC connector on the exterior side (for the remote oscillator
connection). Feedthrough placement defines the sensor to feedthrough cable length. Lengths over 30
inches negatively effect crystal stability and usable life. Another pipe may also be provided for compressed
air (for shutter activation).
Electrical connections from crystal sensor through feedthrough to remote oscillator cable.
The typical crystal sensor has a microdot coaxial connector located on the perimeter of its body for
electrical connection to the enclosed crystal. A teflon cable brings this connection to the chamber wall
flange through which it proceeds to the exterior of the chamber via a vacuum feedthrough.
The electrical
cable from the sensor head to the vacuum feedthrough should be wrapped around the water lines [securing]
using up all excess length in the process. The chamber, the sensor body, the outer conductor of the
microdot connector and the outer conductor of the BNC connector are electrically interconnected and must
be at earth ground for proper use with the remote oscillator and the STC-2000A. Grounding also provides
safety benefits and lessens signal noise. The remote oscillator can be connected directly to the exterior of
the feedthrough BNC if room permits. A 6 inch cable is used if there is not enough room. The cable from
the remote oscillator to the STC-2000A sensor card can be as long as 100 feet. These interconnects are 50
ohm coaxial cables. The STC-2000A sensor card has 2 crystal sensor inputs (BNC males) that, when
installed in the STC-2000A, are labeled on the back panel as: 1 and 2. The text SENSORS also appears on
the back panel to generally describe the connectors in this area.
Sensor side
OSC-100A OSCILLATOR
Push to Test
Serial No.
4571
instruments
East Syracuse, NY
STC-2000A side
The crystal sensor has an opening which presents an area of the crystal surface to the accumulating
deposition material. During setup and initial evaporant material heating/outgassing, this opening on the
sensor should be covered to prevent deposition on its surface. Typically a metal shutter (that can be
SECTION 2.XX page 34 of 292