The coaxial cable on the vacuum side of the leadthrough connects the leadthrough to the
crystal head. The cable is insulated with PTFE and you do not need to use more insulation
unless you use temperatures above 300 °c inside the chamber. For normal work, wrap the
coaxial cable loosely round the coiled copper tubes. If you use temperatures above 300 °C,
wrap the cable and coiled copper tubes with aluminium foil to protect them. It is important
that you do this if you use electron beam and RF sputtering sources.
.
You must position the crystal head carefully in RF sputtering systems to avoid interference.
You must provide sufficient cooling-water to the Water Cooled Crystal Holder, especially
when you are using radiant heaters. You may use the Water Cooled Crystal Holder without
cooling-water only for short, low temperature depositions. If you use water which is too
cold, condensation may form on the crystal and the crystal head when the coating system
is vented to atmospheric pressure. Too much condensation may cause the crystal to stop
oscillating; this condition is temporary and the crystal will function correctly when the
condensation evaporates.
Use a shutter to shield the crystal head during the initial soak period to protect the crystal
from any spitting that may occur. If a small droplet of molten material hits the crystal
surface, the crystal may be damaged and it may stop oscillating.
3.4
How to install the Water Cooled Crystal Holder
A typical installation of the Water Cooled Crystal Holder is shown in Figure 2. Figure 4 shows
the water hose connections for an A UTa 306. Figure 5 shows how to use the quick fit connectors.
Before you start the installation procedure below, select the best baseplate lead through hole for
your application. To prevent vibration of the crystal head when it is in use, you may want to
attach the crystal head to a nearby support in your chamber; to do this, you must make a bracket
which can be fixed to the two M3 tapped holes in the back of the crystal head (refer to Figure 3).
One of the cooling-water connectors on the bottom of the lead through has a water filter inserted
into it (refer to Figure 6, item 13): you must identify this connector and ensure that the water
supply hose is fitted to this connector.
You must cut the nylon tube (supplied with the Water Cooled Crystal Holder) to the correct
length for your installation: the length of tube that you will require will depend on the position
of the baseplate lead through hole you have used for the Water Cooled Crystal Holder. For the
AUTO 306, the maximum length of tube that you will require (if you have used the hole furthest
from the side panel with the water hoses) will be about 1.4 m. Cut the tube so that, when it is
installed, there are no loops or bends in the tube which could restrict the water flow.
Water Cooled Crystal Holder
9
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