Measurements of Fixed Inductors

Inductance
The inductance is measured with a Q-meter, LCR meter or animpedance analyzer.

• Fixed inductors for signals: Use of a Q-meter in which the frequency is for direct readout of the inductance or at the specified frequency.
• Inductors for high current power line circuits: 1kHz or 100kHz.

Q Factor
The unloaded Q is measured with a Q-meter, LCR meter orimpedance analyzer. The frequency of measurement is that at which the inductance hasbeen measured or at a different frequency as specified. However, forhigh current power line inductors, the resistance is measured andthe Q may be neglected.

DCR (DC Resistance), SRF (Self-Resonant Frequency)
DCR: A digital multimeter is used for measurement;
SRF: Measured with a Q-meter, impedance analyzer or network analyzer.

Dielectric Strength
For specimen coil, apply 100V DC for 5 seconds between the shielding case and terminals. There should be no damage orabnormalities in the inductor.

Maximum Allowable Current
The maximum allowable current is a DC Current which causes initialinductance to decrease by 10% or 30%. Or coil temperature to rise by 20°C or 40°C, whichever is smaller. (Reference ambient temperature: 20°C)

Solderability
After immersion of terminals in flux for 5 to 10 seconds, dip theterminals in the solder bath at 245±5°C for 2±0.5 seconds. Makecertain that more than 3/4 of the surface of the terminals are coatedwith new solder.

Dry Heat Test
The change in inductance, if any, is measured after exposure to 85±2°C in a test chamber for 500±12 hours and for 1 to 2 hours at room temperature.

Shock Tests
The change in inductance, if any, is measured after the following tests.

• Free Fall Drop Test: A specimen coil is mounted on a test board and dropped freely 3 times from a height of 1 meter.
• Impact Tester: A specimen inductor is mounted on a test board and dropped 3 times in three directions with shock applied for 0.01 seconds at 981 m/s². The change in inductance, if any, is measured after the tests.

Vibration Test
The change in inductance, if any, is measured after the following condition:

• A specimen coil/inductor is mounted on a test board of vibration instrument.
• Overall amplitude: 1.5mm, frequency range: 10~55Hz, and swept in the (10~55~10)Hz order per minute for 2 hrs
  in each of the 3 directions for total of 6 hrs.

Humidity Test
The change in inductance, if any, is measured after exposure in a test chamber to humidity of 90% to 95% R.H.
at 60±2°C for 500±12 hours and 1 hour exposure at room temperature.