Can you use epoxy to protect an NTC thermistor? The simple answer to that question is yes. In fact, using epoxy is considered one of the most common ways to safeguard thermistors from issues that could potentially impair performance. The chemical characteristics of industrial-grade epoxy, high thermal conductivity, and dielectric strength make it an ideal choice for protecting thermistors.
Epoxy coated thermistors look like tear-drop shaped beads that have two separate radial wire leads coming from the bead. In many cases, this type of thermistor is used within devices that are within close proximity to moisture. Epoxy coated thermistors are used in medical devices used for measuring air temperature and airflow. An epoxy bead thermistor is also found in automotive applications that control and monitor seat warming and air conditioning.
The three main reasons to use epoxy sealing include:
Protecting a thermistor from moisture: Potting (epoxy coating) provides a sealed barrier that prevents vapor from coming in contact with the sensor.
Adding physical protection to the thermistor: After sealing a sensor in epoxy, the sensor is protected from accidental impacts that can occur during operations and manufacturing. NTC thermistors without this protection are in jeopardy of implications that can cause a loss of critical tolerances that are necessary for long-term accuracy.
Adding electrical insulation to the thermistor: An epoxy coat and seal can also provide electrical insulation. Any electrical contact with other components can damage the device.
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