Installation Instructions
Silicon Diode and GaAlAs High Temperature Sensor
DT-470/471/670/671-CU-HT and TG-120-CU-HT Package
Lake Shore Cryotronics, 575 McCorkle Blvd. Westerville, OH 43082-8888. Visit Our Website: www.lakeshore.com.
(614) 891-2243
– Phone, (614) 891-1362 – Fax, E-Mail: [email protected], [email protected].
CAUTION:
This temperature sensor is sensitive to electrostatic discharge (ESD). Use ESD precautionary
procedures when handling, or making mechanical or electrical connections to this device in order to avoid
performance degradation or loss of functionality.
+There are three aspects of using a cryogenic temperature sensor which are critical to its optimum performance. The first
involves the proper mounting of the sensor package. The second relates the proper joining of sensor lead wires and
connecting wires. The final concern is the thermal anchoring of the lead wires. Although the sequence in which these areas
should be addressed is not set in stone, all elements covered under each aspect should be adhered to for maximum operating
capabilities of the sensor.
SENSOR MOUNTING
The DT 470/471/670/671-CU-HT and TG-120-CU-HT package
combine a standard SD sensor with a gold-plated copper
mounting bobbin to form the CU-HT. The mounting bobbin of this
package contains a 3.1 mm (0.122 in) diameter hole (0.03 inch off
center) designed for mounting with a #4-40 or M3 screw.
1. A threaded hole in your mounting surface is necessary for
mounting the sensor package. The hole in the sensor
package will accommodate a #4-40 or M3 screw. A brass
screw is recommended due to the thermal
contractions/expansions of the final assembly.
2. The threaded hole and surrounding surface should be cleaned with a solvent such as acetone followed by an isopropyl
alcohol rinse. Allow time for the solvents to evaporate before sensor mounting.
3. For use to 500 K, apply a small amount of Apiezon
®
H grease to the threads of the screw. To ensure good thermal contact
between the sensor and mounting surface, use an indium washer/preform (use to 425 K only) or a thin layer of Apiezon
®
H grease between the mounting surface and the sensor package.
NOTE:
An overabundance of grease will increase the
thermal barrier. Keep the thickness to 0.05 mm or less.
4. Insert screw through sensor mounting bobbin and tighten screw firmly enough to hold sensor in place. Avoid over
tightening (torque of 3 to 5 in-oz [0.02 to 0.035 N-M] should be sufficient).
NOTE:
The high temperature -CU is designed for use up to 500 K (227°C) with a silicon diode sensor or GaAlAs diode.
Subjecting the sensor to temperature in excess of this limit will cause a shift in the sensor values.
LEAD ATTACHMENT
The SD sensor has been attached to the mounting bobbin and encapsulated in Stycast
®
epoxy. The 0.91 m (36 in) heavy build
Polyimide (ML) insulated sensor leads are quad twist, 36 AWG, phosphor bronze wire which are thermally anchored to the
bobbin. Teflon
®
tubing is used as a strain relief to reinforce the leads at the bobbin assembly. Standard lead configuration for
the CU-HT is Red (I
–), Green (V–), Black or Dark Blue (V+), Clear (I+).
CU (HT) Package
-
Four-lead measurement scheme
The current is confined to one twisted pair of current leads with the sensor voltage measured across the twisted pair of voltage
leads as shown in Figure 1.
