How to measure the capacitance of MLCC SMT Capacitors

Passives Capacitors
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Many customers would like to test capacitors they receive themselves in order to verify their capacitance. There are a few reasons why a test may not come out the way you’re hoping it will.

  1. The test measurement was not performed correctly or within the specified measurement conditions.
  2. The test may have used incorrect meter settings, or the measuring equipment used does not have adequate ability to accurately measure MLCCs.
  3. The parts are not intended to be within their listed specifications fresh off the reel - see HERE for more information.

We suggest the following testing steps, with checklist, to help engineers to clarify what they need to be aware of during the measurement.

Part 1: Measurement Requirement
Measuring frequency and voltage are important to measure the right value of ceramic capacitors. Please check out the Manufacturer and Series and confirm in the datasheet for your specific capacitor to confirm what measuring frequency and voltage are needed.

[Suggested Checklist]

  • Measuring Frequency : _______________________ Hz
  • Measuring Frequency : _______________________ V

Part 2: Measurement Equipment Requirement and Settings
Since most multimeters are unable to be configured to meet the specified measurement conditions for your caps, LCR meters are generally used to measure MLCC capacitance. Try to make use of a measuring jig, it holds the sample steady during the measurement. You should then then turn on the Automatic Level Control (ALC) function of your LCR meter.

ALC
Figure 1 Once the ALC is On, an “*” (asterisk) symbol will appear on the voltage level display.
[ Hint : Why do we need to turn on ALC? Please study HERE ! ]

[Suggested Checklist]

  • Was a fixture jig used (Yes or No) : _______
  • Was the Automatic Level Control (ALC) turned on (Yes or No) : _______

Part 3: Heat Treatment (De-aging)
Class 2 (high dielectric) MLCC capacitors, due to their physical construction, lose capacitance as time elapses. This attribute is called “aging” of capacitance. That’s why customers will sometimes find the capacitance of their devices is lower than the specification. Generally, the capacitance value will return to the specification mentioned after a heat-treatment (baking) at 150℃(+0/-10℃) for 1 hour, and staying to cool down at room temperature in 24 hours (+/-2) hours.

Prior to measuring the capacitance, a capacitor should be heat treated at 150℃+0/-10℃ for 1 hour and maintained in ambient air for 24±2 hours.

[Suggested Checklist]

  • Which Class of MLCC (Class 1 – C0G or NP0 / Class 2 – Other that C0G or NP0) : _______
  • Did the sample undertake the heat treatment (baking) at 150℃+0/-10℃ for 1 hour and maintain in ambient air for 24±2 hours ? (Yes or No) : _______

[ Hint : Why need de-aging only for Class 2 ? Please study HERE ! ]

You can also check out this video to get a succinct explanation!

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