Iron Nickel (Fe-Ni) Powder Core Inductor
Quick AnswerA High Flux powder core / iron nickel powder core inductor uses a 50%Fe–50%Ni alloy powder core with a distributed air gap to achieve saturation flux density Bs≥1.5T, stable inductance under DC bias, a −40°C to +180°C operating range and core loss ≤300 kW/m³ at 100 kHz. It is the preferred choice for high-current power inductors in AI GPU VRM, EV chargers, solar inverters, energy storage and server power supplies.
Series Specifications
| Series Part | Inductance (µH) | Isat (A) | DCR (mΩ) | Size (mm) | Application |
|---|---|---|---|---|---|
| YTFN-6028 | 0.10 – 10.0 | 18 – 65 | 0.45 – 8.5 | 7.0 × 6.6 × 2.8 | AI GPU VRM |
| YTFN-8040 | 0.22 – 22.0 | 25 – 85 | 0.28 – 6.2 | 8.0 × 8.0 × 4.0 | Server POL |
| YTFN-1045 | 0.33 – 47.0 | 30 – 110 | 0.18 – 4.5 | 10.0 × 10.0 × 4.5 | Data Center |
| YTFN-1265 | 0.47 – 100 | 40 – 150 | 0.12 – 3.2 | 12.5 × 12.5 × 6.5 | High Power |
| YTFN-1510 | 0.68 – 150 | 50 – 180 | 0.10 – 2.2 | 15.0 × 15.0 × 10.0 | ESS Converter |
Engineering Resources
A Fe-Ni (iron nickel) inductor is a power inductor whose core is made from a 50%Fe–50%Ni alloy powder pressed with a distributed air gap. FeNi powder cores of this type are known in the industry as High Flux cores. Unlike gapped ferrite designs, the air gap is distributed throughout the part, which keeps inductance stable under heavy DC bias and produces clean EMI behavior. This guide explains the material, the engineering trade-offs, the YTFN series specifications and how to specify a custom Fe-Ni inductor for your application.
1. What Is a Fe-Ni Inductor?
Fe-Ni inductors use an iron-nickel alloy powder core (50% iron, 50% nickel) bonded with an organic binder and pressed into a toroidal, E-shape or custom geometry. The insulating binder between alloy particles forms a distributed air gap, so the core combines a high saturation flux density with soft-saturation behavior: inductance rolls off gradually rather than collapsing abruptly at high current.
That combination is why Fe-Ni inductors are specified in high-current power delivery where ferrite would saturate or need a large physical air gap: AI GPU VRM, server POL, EV chargers (OBC/DC-DC), solar inverters, energy storage converters and industrial power supplies.
2. FeNi Core Material Properties
| Property | FeNi (Iron Nickel) Powder Core |
|---|---|
| Saturation flux density (Bs) | ≥ 1.5 T |
| Permeability range | 14 – 160 |
| Core loss @ 100 kHz / 100 mT | ≤ 300 kW/m³ |
| Operating temperature | −40°C to +180°C |
| Permeability variation vs temperature | ≤ 8% (−40°C to +180°C) |
| DC bias stability | Distributed air gap; soft saturation |
| EMI behavior | Gapless design, low fringing flux |
| Curie temperature (Tc) | ≥ 450°C |
3. Fe-Ni Inductor vs Ferrite, Sendust and MPP Inductors
Every core material is a compromise. The table below compares the four materials most commonly considered for power inductors so you can check where Fe-Ni fits your design.
| Property | Fe-Ni (Iron Nickel) | Ferrite | Sendust | MPP |
|---|---|---|---|---|
| Saturation Bs | ≥1.5T | 0.3–0.5T | ~1.05T | ~0.75T |
| Permeability range | 14–160 | 300–15000 | 26–125 | 14–550 |
| Core loss @100kHz | ≤300 kW/m³ | Very low | Moderate | Low |
| DC bias stability | Excellent | Poor (needs gap) | Good | Excellent |
| Temperature stability | Excellent (−40 to +180°C) | Fair (Curie limit) | Good | Good |
| Best fit | High-current power, AI, EV, solar | Low-power high-frequency, transformers | EMI filters, PFC | Precision filters, audio |
4. How FeNi Powder Core Inductors Are Made
- Alloy atomization: high-purity Fe and Ni are melted and atomized into fine alloy powder
- Coating & mixing: particles are insulated with a ceramic/organic coating and mixed with binder to create the distributed air gap
- Pressing: the powder is pressed into the required geometry (toroid, E-core, custom shape)
- Heat treatment: cores are annealed to relieve stress and restore magnetic properties
- Winding & assembly: copper windings, flat wire or litz wire are applied, followed by termination and molding
- 100% electrical test: inductance, DCR, saturation current and permeability are tested on every part
5. Fe-Ni Inductor Design Considerations
- DC bias: define the maximum operating current and the acceptable inductance roll-off (typically ≤20% at rated Isat)
- Inductance tolerance: Fe-Ni cores are available in permeability grades from 14 to 160; choose the grade that balances size and bias stability
- Core loss vs copper loss: at high ripple current the core loss term dominates — request loss data at your actual frequency and flux swing
- Thermal budget: Fe-Ni operates to +180°C with stable permeability, but the winding temperature rise still limits the design
- EMI: the gapless core structure reduces fringing flux, simplifying EMI filter design and shielding requirements
- Packaging: molded SMD inductors (YTFN series) suit automated assembly; toroids suit higher-current chassis designs
6. Key Applications
- AI GPU VRM and accelerator modules (H100, B200): MHz metal inductors with high current density
- Server POL / VRM: stable inductance at large DC bias
- EV chargers, OBC and DC-DC: AEC-Q200 qualified cores for 800V platforms at 20–100 kHz
- Solar inverters (string & central): 30% volume reduction vs ferrite at Bs≥1.5T
- Energy storage converters (ESS): high-current output chokes, Isat up to 180A
- Industrial power supplies, UPS and motor drives: low-loss EMI filter and power chokes
7. YTFN Series Fe-Ni Inductor Specifications
The YTFN series are molded SMD Fe-Ni powder core inductors. The standard portfolio below covers AI, server, data-center, high-power and energy-storage designs. Full datasheets are available on request.
| Series | Size (mm) | Inductance (µH) | Isat (A) | DCR (mΩ) | Typical Application |
|---|---|---|---|---|---|
| YTFN-6028 | 7.0 × 6.6 × 2.8 | 0.10 – 10.0 | 18 – 65 | 0.45 – 8.5 | AI GPU VRM |
| YTFN-8040 | 8.0 × 8.0 × 4.0 | 0.22 – 22.0 | 25 – 85 | 0.28 – 6.2 | Server POL |
| YTFN-1045 | 10.0 × 10.0 × 4.5 | 0.33 – 47.0 | 30 – 110 | 0.18 – 4.5 | Data Center |
| YTFN-1265 | 12.5 × 12.5 × 6.5 | 0.47 – 100 | 40 – 150 | 0.12 – 3.2 | High Power |
| YTFN-1510 | 15.0 × 15.0 × 10.0 | 0.68 – 150 | 50 – 180 | 0.10 – 2.2 | ESS Converter |
8. Custom Fe-Ni Inductor Development
Standard catalog parts are a starting point. YUTE Magnetics offers OEM/ODM custom development: custom core geometry, permeability grade, winding type (round wire, flat wire, litz, multi-turn), inductance and DCR targets, and AEC-Q200 qualification where required. Engineering responds within 24 hours with a free technical evaluation; standard MOQ is 10,000 pcs per model with negotiable sample orders, and lead time is 2–4 weeks for standard models, 6–8 weeks for custom designs.
Frequently Asked Questions
What does Fe-Ni mean in an inductor core?
Fe-Ni stands for iron-nickel. FeNi powder cores are made from a 50% iron / 50% nickel alloy powder pressed with an insulating binder. The distributed air gap from the binder gives high saturation flux density (Bs ≥ 1.5T) and stable inductance under DC bias.
What is the saturation flux density of FeNi cores?
FeNi powder cores reach Bs ≥ 1.5T, roughly 3–5 times the saturation flux density of ferrite (0.3–0.5T). This allows a smaller core for the same current, typically about 30% volume reduction vs ferrite in high-current designs.
Are Fe-Ni inductors suitable for MHz switching frequencies?
Yes. FeNi cores keep core loss ≤ 300 kW/m³ at 100 kHz and remain usable from 20 kHz into the MHz range. For AI GPU VRM and compact converters switching in the 1–100 MHz range, YUTE also offers the YTMF metal inductor series (0.047–6.8 µH).
What is the difference between FeNi and MPP cores?
MPP (Molypermalloy powder) uses a nickel-iron-molybdenum alloy and offers very low core loss and excellent bias stability, but lower saturation (Bs ~0.75T) and higher cost. FeNi offers roughly double the saturation flux density with excellent temperature stability, making it the better choice for high-current power conversion.
Can you make custom Fe-Ni inductors?
Yes. We provide OEM/ODM custom development including core geometry, permeability grade, winding type, inductance/DCR targets and AEC-Q200 qualification. Send your inductance, current, size and frequency targets through the contact form; engineering responds within 24 hours with a free technical evaluation.
Do you manufacture custom iron nickel (NiFe) cores?
Yes. We manufacture custom FeNi powder cores and inductors in our own factory in Haining, Zhejiang, China — from alloy control and pressing to heat treatment, testing and volume production. Custom options include core geometry, permeability grade (14–160) and wound inductor assembly with inductance/DCR targets.
What qualifications does your NiFe core production hold?
NiFe core and inductor production runs under IATF 16949 quality management with AEC-Q200 qualification for automotive and server-grade programs. In-house testing covers permeability, core loss, saturation flux density, DC bias and dimensions, with lot traceability for volume orders.
How do I get NiFe core samples for evaluation?
Samples are available for engineering evaluation. Share your inductance, current, frequency, size and temperature targets through the RFQ form, and engineering will recommend the permeability grade and core geometry, then confirm the sample plan within 24 hours.
Related Products
Need a datasheet or samples?
Our engineering team responds within 24 hours with a free technical evaluation and sample support.
Request A Quote