Frequently Asked Questions
How does aging affect thermistor stability?
“Thermometric drift” is a specific type of drift in which the drift is the same amount of temperature at all temperatures of exposure. For example, a thermistor that exhibits a -0.02°C shift at 0°, 40° and 70°C (even though this is a different percentage change in resistance in each case) would be exhibiting thermometric drift. Thermometric drift: (1) occurs over time at varying rates, based on thermistor type and exposure temperature, and (2) as a general rule, increases as the exposure temperature increases. Most drift is thermometric.
What happens if my application exceeds the temperature rating?
Intermittent temperature incursions above and below the operating range will not affect long-term survivability. Encapsulate epoxy typically begins to break down at 150°C and the solder attaching leads to the thermistor body typically reflows at about 180°C. Either condition could result in failure of the thermistor.
Are thermistors ESD sensitive?
Per MIL-DTL-39032E, Table 1, thermistors by definition are not ESD sensitive.
What is the resolution of a thermistor?
There is no limit to the resolution of a thermistor. The limitations are in the electronics needed to measure to a specified resolution. Limitations also exist in determining the accuracy of the measurement at a specified resolution.
Are QTI thermistors RoHS compliant?
(What if I don’t want a lead free part?) Quality Thermistor maintains two separate manufacturing lines to meet the specific environmental needs of our customers. One line is dedicated to RoHS compliance and the other is maintained for traditional tin/lead parts for military, aerospace and medical applications.
Does the length of wire impact the accuracy of a thermistor?
With a thermistor, you have the benefit of choosing a higher base resistance
if the wire resistance is a substantial percentage of the total resistance. An
example of this would be a 100-ohm thermistor vs a 50,000 ohm thermistor
with 10’ of 24 AWG wire.
Total wire resistance = 10’ x 2 wires x 0.02567 ohms per foot = 0.5134 ohms
