INFICON MDC-260 Thin Film Deposition Controller - Manual (Page 113)

MDC-260 DEPOSITION CONTROLLER
SYSTEM INSTALLATION 9-1
9. SYSTEM INSTALLATION
9.1 SENSOR HEAD DESCRIPTION
The sensor head is designed for simple installation and easy crystal replacement.
It consists of two parts; a water-cooled gold-plated 304 stainless steel housing
which is permanently positioned in the vacuum system, and a quickly removable
gold plated 304 stainless steel crystal holder which snaps into the housing. The
crystal holder accommodates an industry standard 0.550” diameter crystal.
This design provides several convenient features in performance and use. The
crystal holder is thermally shielded by the water-cooled housing insuring
excellent crystal performance in temperature environments up to 300°C. The
sensor may be baked out with no water-cooling to temperatures up to 250
°C.
The exposed crystal electrode is fully grounded to effectively eliminate problems
due to free electrons and RF interference.
The crystal holder is easily removed and installed even in awkward locations in
the vacuum system. Once removed from the housing the crystal is still retained in
the crystal holder by a snap on retainer. The crystal can be easily replaced
without tools at a more convenient place, such as a clean bench.
The housing is provided with four tapped (4-40) holes for convenient mounting,
1/8” diameter X 5” long inlet and outlet water cooling tubes, and a coaxial
connector (See Figure 9-6). The electrical connection to an instrumentation
feedthrough is made with a 30” coaxial cable. Both ends of the cable terminate
with standard Microdot
® S-50 type connectors. Cable lengths up to 60” are
available upon request.
9.2 SENSOR HEAD INSTALLATION
The sensor head can be installed in any appropriate location in the vacuum
chamber, preferably more than 10 inches from the evaporation source. It can be
supported by its integral mounting bracket furnished with two #4-40 tapped holes.
The internal (vacuum) cable, supplied with the sensor kit, connects the sensor
head to the dual water/electrical feedthrough, to which the oscillator is attached.
The cable length from sensor head to feedthrough connection should not exceed
60 inches. Shield the sensor cable in the most expedient way possible to protect it
from radiation heat released from the evaporation source or the substrate heater.
The water-cooling tube connects to the feedthrough by brazing or vacuum
couplings. If necessary, both cable and water lines may be wrapped in aluminum
foil to extend their useful life. The mounting tabs may be used to install a
radiation shield to specifically protect the Microdot
® connector and cable at its
attachment point to the head.
Water-cooling of the sensor head should always be provided except during short
depositions at low temperatures. In all cases, head operating temperature should
not exceed 100°C. Sufficient cooling for thermal environment to 300°C can be
provided by approximately 0.2-gpm water flow.