Form Number F007-00-00_ H —©2015 —25 May 2015
HEAT SINKING/THERMAL ANCHORING
Thermal anchoring of the leads is an important factor in cryogenic measurements. As part of the design of the CY packaging,
the leads are already heat sunk around the copper bobbin. Depending on the system design, additional heat sinking between
room temperature and sensor temperature may be necessary.
For additional heat sinking/thermal anchoring:
1. Connecting wires should be thermally anchored at several temperatures between room temperature and cryogenic
temperatures to guarantee that heat is not being conducted through the leads to the sensing element.
2. A simple thermal anchor can be made by winding the wires around a copper post, bobbin, or other thermal mass. A
minimum of five wraps around the thermal mass should provide sufficient thermal anchoring. However, if space permits,
additional wraps are recommended for good measure. To maintain good electrical isolation over many thermal cycles, it
is good practice to first varnish a single layer of cigarette paper to the anchored area then wrap the wire around the
paper and bond in place with a thin layer of IMI 7031 Varnish. Formvar™ wiring insulation has a tendency to craze with
the application of IMI varnish. If used, the wires cannot be disturbed until the varnish is cured and all solvents have
evaporated (typically 12 to 24 h).
CRYOGENIC ACCESSORIES —Recommended for proper installation and use of DT-470/471/670/671 CY sensor:
Apiezon®Type N and H Grease: P/N GAN-25 and GAH-25—25 g tube. Low viscosity, easy to use, solidifies at cryogenic
temperatures, excellent lubricant. Difference is melting point: Type N is 316 K, Type H is 523 K.
Heat Sink Bobbins: P/N HSB-40 large, HSB-8 small. Large gold-plated copper bobbin holds up to 40 wires, small gold-
plated copper bobbin holds up to 8 wires, depending on wire gauge and number of turns.
High-Temperature Solder: P/N SLT-10—3 m (10 ft). Greater lead content (90% Pb 10% Sn) for soldering in applications up
to 500 K.
Indium Foil/Solder: P/N IF-5 for 5 foil sheets (51 mm [2 in] square × 0.13 mm [0.005 in] thick), ID-10-31/ID-10-56 for 10
disks, 7.9 mm (0.31 in) or 14.2 mm (0.56 in) diameter × 0.13 mm [0.005 in] thick, respectively. Indium is 99.99% pure, an
exceptional pressure seal, and extremely malleable.
Ostalloy®158 Solder: P/N SOSY-16—16 oz reusable eutectic alloy with sharply defined melting point of 343.16 K (70 °C).
Stycast®Epoxy 2850FT, Catalyst 9: P/N ES-2-20—20 packets, 2 g each. Provides permanent attachment, has excellent
low temperature properties, is a poor electrical conductor, and exhibits low cure shrinkage. [Requires Hazardous shipping.]
VGE-7031 Varnish: P/N VGE-7031—0.5 L (1 pt) can. Provides nonpermanent attachment, is an excellent thermal conductor,
and is easy to apply and remove. [Requires Hazardous shipping.]
Instruments: Lake Shore sells a complete line of instrumentation used with your sensor, such as: current sources,
temperature controllers, monitors and thermometers, temperature scanners and transmitters.
Wire: Lake Shore offers numerous types of wires for various applications, including phosphor-bronze wires: single strand,
Duo-Twist™, Quad-Twist™, Quad-Lead™, Nichrome heater wire, non-magnetic Manganin wire, and more.
Cable: Lake Shore offers ultra-miniature coaxial cable (type C, SC, and SS), semi-rigid coaxial cable (type SR), and a robust
4-wire CryoCable™ (type CYRC).
For complete product description and detailed specifications on the above accessories and instruments, consult the
Lake
Shore
Temperature
Measurement
a
nd
Control
Catalog,
call
at
(614)
89
1
-2243,
e-mail
at
s[email protected], or visit our website at www.lakeshore.com.
