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Should I Calibrate My Electronic Circuit in a Humid Environment?

Electronic circuits, or paths for electrical flow, reside in many different devices, from industrial pressure gauges to digital measuring multimeters. Typically, electronic circuits require periodic calibration for correcting any inaccuracies that occur over time from basic device movement, especially for handheld or precision measuring instruments. However, the calibration process should not be performed in a humid environment.

Electronic Circuit Identification
- Electronic circuits consist of numerous electronic components and connecting leads. Each circuit is unique, based on the intended design and use of the device. Components can include resistors, transistors, capacitors and integrated microchips. Each component connects to the continuous circuit through leads, or traces, embedded in a printed circuit board (PCB).
Calibration and Humidity
- Calibration of any electronic circuit involves matching and adjusting the circuit's functions with a standard scale. For example, a pressure gauge should match a standardized pressure gauge reading, such as 20 psi (pressure per square inch). However, the uncalibrated gauge may reflect a reading of 21 psi, instead of the intended 20 psi. The internal electronic circuit would need an adjustment to reflect an accurate reading, based on the standardized pressure gauge's setting. However, the standardized setting is based on an average temperature and humidity level allocated by the device's manufacturer, commonly between 70 and 80 degrees Fahrenheit and ranging between 40 and 60 percent humidity. High humidity levels change the electronic circuitry's reactions, displaying a skewed reading that may or may not be correct.
Humidity Effects
- Humidity causes expansion and contraction of the PCB material. Thin traces and small components are cracked and damaged easily with high humidity. The device will display values based on the damaged PCB readings, which will be a misrepresentation of reality. As a result, performing calibration in high humidity will adjust the circuitry to a value that may match the standardized scale, but it will not remain at that value after calibration. After the device is moved to an average humidity region, such as on a job site, the saved calibration value will change as the PCB stops expanding and contracting. The resulting device will be even more inaccurate until it is calibrated again.
Considerations
- Verify humidity levels before calibrating an electronic circuit. Place a thermometer with a digital reading of both temperature and humidity in the calibration area. Refer to the thermometer before any calibration procedures. Many businesses control both temperature and humidity levels in precision calibration rooms.

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