Sensor Mounting
General Comments
Before installing the CY7/670 series sensor, identify which lead is the anode and which lead is the cathode by referring to the accompanying device drawings. Be sure that lead identification remains clear even after installation of the sensor, and record the serial number and location.
The procedure used to solder the connecting leads is not very critical and there is very little danger in overheating the sensor. If for some reason the leads need to be cut short, they should be heat sunk with a copper clip or
For all adapters except the CY, CU, and DI, the leads are
When installing the sensor:
•Make sure there are no shorts or leakage resistance between the leads or between the leads and ground. CYAV varnish or epoxy may soften
•Avoid putting stress on the device leads and allow for the contractions that occur during cooling that could fracture a solder joint or lead if installed under tension at room temperature.
The CY7/670 series sensor is designed for easy removal for recalibration checks or replacement, and the following discussions for each of the adapters are geared in this direction. If semi- permanent mountings are desired, the use of OB- CY10 or
CY7/670-SD
The SD version is the basic package for the CY7/670 series sensor line, from which all other configurations are made using the appropriate adapter. The base of the device has a gold metallized surface and is the largest flat surface on the sensor. The base is electrically isolated from the sensing element and leads, and all thermal contact to the sensor must be made through the base.
2
A thin braze joint around the sides of the SD package is electrically connected to the sensing element. Contact to the sides with any electrically conductive material must be avoided. When viewed base down and with leads towards the observer, the positive lead (anode) is on the right.
For a removable mount, the SD sensor can be held against the mounting surface with the CO adapter (see below) or similar clamping mechanism. Any method of clamping the sensor must avoid excessive pressure and should be designed so that thermal contractions or expansions do not loosen contact with the sensor. For uses restricted to below 325 K, a thin layer of CYAG grease should be used between the sensor and sample to enhance thermal contact.
The SD package can also be bonded with a low temperature epoxy. The sensor should be pressed firmly against the surface during curing to assure a thin epoxy layer and a good thermal contact. The device may be removed in the future by using the appropriate epoxy stripper.
The SD adapter can be soldered using a rosin flux
1.Tin the base of the sensor using a low wattage, temperature controlled soldering iron that will not exceed 200 °C. Use only a minimal amount of solder. Tin the surface to which the sensor is to be bonded and again, avoid an excessive thickness of solder. Clean both the sensor and the mounting surface of any residual flux.
2.Reheat the mounting surface to the melting point of the solder, press the device into position and allow the sensor to warm to the melting point of the solder.
3.After both tinned surfaces have flowed together, remove the heat source and let the sample and sensor cool.
Under no circumstance should the sensor be heated above 200 °C and the solder must be limited to only the base of the sensor. Excess solder running up the sides of the SD package can create shorts. Repeated mounting and demounting of a soldered sensor may eventually cause wetting deterioration and ruin the thermal contact to the sensing element, although the nickel buffer layer should minimize these problems.
CAUTION
The preferred method for mounting the SD sensor is either the CO adapter or bonding with epoxy. Omega Engineering, Inc. will not warranty replace any device damaged by a
