What are the Three Main Categories of EMI Inductor Core Materials?

What are the three main types of magnetic core materials for EMI inductors?

Category 1: Ferrite Core

Mn-Zn ferrite,Ni-Zn ferrite

Type 2: Metal magnetic powder core

Sendust,MPP,Fe-Si,Carbonyl Iron

Category 3: Nanocrystalline alloys

Iron-based nanocomposite, iron-based amorphous

Ten evaluation indicators for assessing magnetic materials?

1. Permeability (µ)

Definition: The strength of a material's ability to be magnetized under an external magnetic field is divided into initial permeability (μ₀) and effective permeability (μₑ)

2. Saturation flux density (Bsat)

Definition: The maximum magnetic induction intensity (unit: Tesla T or Gauss Gs) of a material when it reaches magnetic saturation under a strong magnetic field

3. Coercivity (Hc)

Definition: The strength of the counteracting magnetic field required to reduce the magnetization to zero (unit: A/m)

4. Loss characteristics

Hysteresis loss: It is proportional to the area of the hysteresis loop. At high frequencies, materials with low coercivity should be selected

5. Resistivity (ρ)

Impact: The higher the resistivity, the lower the eddy current loss, and the better the high-frequency performance (such as manganese-zinc ferrite semiconductors, nickel-zinc ferrite insulators)

6. Curie temperature (Tc)

Definition: The critical temperature at which a material loses its ferromagnetism

7. Frequency characteristics

8. Temperature stability

Indicators: Permeability temperature coefficient (αμ) and Bsat temperature coefficient

9. Initial inductance (L₀) and DC bias characteristics

Test condition: Inductance value at a specified frequency (e.g. 100 kHz) and bias current

10. Mechanical strength and processability

Consideration: Whether the material is easy to process into toroidal, E-type, and other magnetic cores, as well as its resistance to cracking and wear (such as the high brittleness of ferrite)