Spherical FeSiCr powder, D50 10-25µm, for MHz molded power inductors. Cr-passivated for 85/85 humidity life. Custom Si/Cr ratios and coated grades.
QUICK ANSWER
FeSiCr powder is an iron-silicon-chromium soft magnetic alloy (typically Fe-6.5Si with 2-6% Cr) atomized into fine spherical powder for molded (molding) power inductors — the miniature shielded inductors inside smartphones, laptops, and server voltage regulators. The chromium addition provides corrosion and oxidation resistance that pure FeSi lacks, enabling fine powders to survive molding and deliver stable inductance over the product lifetime.
Molded inductors are made by pressing insulated magnetic powder directly around a wound coil in a die — the powder is simultaneously the core and the shield. This demands fine, spherical, flowable powder (typically D50 10-25 µm) that packs densely under tonnage-scale pressing, insulates per-particle to control eddy loss, and resists corrosion because the molded body has no hermetic case. FeSiCr answers all three: the alloy's resistivity cuts eddy loss at the 1-5 MHz switching of modern POL converters, and chromium passivation survives humidity testing that rusts plain FeSi.
MATERIAL DATA
Lot-level controls focus on the chemistry, particle characteristics, and process values that influence manufacturing consistency and finished-part performance.
| Element | Content | Performance Role |
|---|---|---|
| Iron (Fe) | Balance (~88-93 wt%) | Magnetic base with high saturation flux density |
| Silicon (Si) | 3-6.5 wt% | Raises electrical resistivity, cutting eddy current loss at MHz frequencies |
| Chromium (Cr) | 2-6 wt% | Passivation — corrosion and oxidation resistance for fine powder stability |
| Oxygen (O) | < 800 ppm | Controlled for insulation quality and loss |
| Carbon (C) | < 0.02 wt% | Magnetic softness preservation |
Final limits can be aligned with the agreed purchase specification.
APPLICATIONS
Molded power inductor manufacture is the sole defining market — and it is enormous. Every smartphone carries dozens of molded inductors; every server CPU and GPU sits behind arrays of voltage-regulator inductors pressed from FeSiCr-type powder. As processors migrate to higher current and faster switching, inductor makers push toward finer powder with better insulation quality, making powder morphology, oxygen content, and size distribution the decisive purchase criteria. Leading inductor makers qualify powder suppliers over years, then buy in high volume against certified lots.
Adjacent applications include automotive molded inductors (AEC-Q200 qualified, harsher humidity and temperature cycling), integrated power modules, and metal-composite EMI suppression cores. The automotive segment is growing fastest — EV power electronics multiply the inductor count per vehicle, and the humidity robustness of FeSiCr over plain FeSi makes it the default alloy choice where qualification standards are toughest.
SOFT MAGNETIC & MAGNETIC MATERIAL POWDERS
CUSTOM SUPPLY
We supply gas-atomized FeSiCr in molding-grade size distributions (D50 10-25 µm standard, finer on request) with certified sphericity, flowability, and oxygen content. Custom Si/Cr ratios for specific loss-corrosion balances, insulation-coated grades, and high-tap-density distributions for maximum pressed density are available. Lot data includes particle size distribution, morphology imaging, and composition. Not export-controlled.
We supply gas-atomized FeSiCr in molding-grade size distributions (D50 10-25 µm standard, finer on request) with certified sphericity, flowability, and oxygen content.
Custom Si/Cr ratios for specific loss-corrosion balances, insulation-coated grades, and high-tap-density distributions for maximum pressed density are available.
Lot data includes particle size distribution, morphology imaging, and composition.
MATERIAL COMPARISON
| Comparison Point | This Product | Carbonyl Iron |
|---|---|---|
| Corrosion resistance | Excellent — Cr passivated | Poor — rusts without heavy coating |
| Core loss at 1-5 MHz | Low | Moderate — higher eddy loss |
| Saturation flux density | 1.2-1.4 T | Up to 2.0 T — higher |
| Particle size available | 5-30 µm atomized | 1-10 µm — finer possible |
| Cost | Moderate | Higher for fine grades |
| Best use | Humidity-critical molded inductors | Ultra-miniature, coated-protected parts |
TECHNICAL FAQ
Need a different chemistry, particle range, or processing route? Our material team can review the requirement and supply window.
Molded inductors are unencapsulated — the pressed powder body faces humidity directly. Chromium forms a passive film that passes 85 °C/85% RH qualification; plain FeSi powder corrodes, inductance drifts, and parts fail field life.
D50 of 10-25 µm with tight span and minimal fines below 3 µm — fines raise insulation demand and pressing pressure without adding magnetic value. We certify the full distribution per lot, laser diffraction.
Yes — send the target (e.g., core loss at 3 MHz/30 mT) and we adjust Si/Cr ratio and size distribution to match or beat it, with qualification samples.
Typically phosphated then resin-coated by the inductor maker. We supply surface condition optimized for phosphating adhesion, and fully coated grades where the customer has no coating line.
No. Iron-silicon-chromium soft magnetic powders ship without licensing requirements.
RELATED PRODUCTS
Compare neighboring grades from the same material family, then review the complete category for additional chemistry and particle options.
50Ni-50Fe soft magnetic powder for current transformer cores, RCD toroids and magnetic shielding. Spherical and flake forms, Mo-bearing high-µ variants, lot test-ring data.
Gas-atomized sendust (Fe-9.6Si-5.4Al) powder for 26-125µ power cores. 1.05T saturation, low loss to 200 kHz, certified lot core-loss data. EV charger and solar inductor grades.
Amorphous and nanocrystalline (FeSiBPCu) powder for 5-500 kHz inductors, wireless charging and EMI cores. XRD-certified amorphous fraction, lot loss data, no rare earths.
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