Knowledge Base

Inductors

The table below summarises the different materials that can be found in Inductors based on Material charts from TDK website.

Legend: *Critical Raw Material,*Mineral of Conflict

Material / Substance

Material Class

Type

Component Section(s) & Function / Role

Manganese*-Zinc Ferrite (MnZn Ferrite)

Ceramic

★ Main

[Active Part] Magnetic core

Nickel*-Zinc Ferrite (NiZn Ferrite)

Ceramic

★ Main

[Active Part] Magnetic core

Iron (Fe)

Steel

★ Main

[Active Part] Soft-magnetic composite/powder core

[Termination] Termination compound

Copper* (Cu)

Heavy Metal

★ Main

[Active Part] Magnet wire forming the inductor winding

[Termination] Base metal of terminals

[Encapsulation] Encapsulation compound (Opt.)

Wire enamel / insulation polymers (PUR, ETFE, Polyamide-imide, Polyester-imide, PA/PA66)

Thermoplastic / Elastomer / Polymer

★ Main

[Active Part] Insulation coating on Cu winding wire and inter-layer bonding:

• PUR (Polyurethane) — universal enamel on all transformer and choke families

• ETFE — fluoropolymer enamel present is some drive transformers

• THEIC/PAI (Polyester-imide / Polyamide-imide) — dual-layer high-temp enamel in some power-line ring-core chokes or signal chokes

• PA (Polyamide) — winding insulation/wrapping

Thermoplastic housings / bobbins (LCP, PC, PPS, PA/PA66/PA6, PBT, PET, Phenolic, DAP)

Thermoplastic / Thermoset

★ Main

[Encapsulation] Thermoplastic housing:

• LCP (Liquid Crystal Polymer)

• PC (Polycarbonate)

• PPS (Polyphenylene Sulfide)

• PA / PA66 / PA6

• PBT (Polybutylene Terephthalate)

• PET (Polyethylene Terephthalate

• Phenolic / Phenolplast (PF)

• DAP (Diallyl phthalate)

Glass fiber (E-glass) — reinforcing filler

Filler

★ Main

[Encapsulation] Reinforcing filler in all thermoplastic and thermoset housing/bobbin compounds (LCP, PC, PA, PBT, PPS, PF, DAP)

Epoxy resin (EP) — encapsulant / potting / bobbin binder

Duromer

★ Main

[Encapsulation] Encapsulation compound

[Active Part] Active part compound in some variants

Tin *(Sn)

Heavy Metal

★ Main

[Termination] Sn outer plating on all terminations

[Encapsulation] Encapsulation compound for some transofrmers and chokes

Nickel* (Ni)

Heavy Metal

★ Main

[Termination] Finish element

Aluminium* oxide (Al₂O₃) — ceramic substrate

Ceramic

---

[Active Part] Non-magnetic ceramic core/substrate

Core coatings / varnishes (Parylene, Alkyd resin, Acrylic resin— core bonding)

Varnish / Duromer / Thermoplastic

---

[Active Part] Surface coatings and bonding agents on magnetic cores:

• Parylene (poly-para-xylylene) — conformal coating on NiZn ferrite core

• Alkyd resin — protective varnish on iron I-core body

• Acrylic resin — insulation coating on Cu winding

Polyurethane (PUR) potting compound

Duromer

---

[Encapsulation] Encapsulation compound

Insulating films / tapes (Polyimide PI, PET)

Thermoplastic / Duromer / Woven

---

[Encapsulation] Encapsulation compound

• Polyimide (PI / Kapton-type)

• PET film/tape

Polydimethylsiloxane (PDMS) (Silicone foam)

Elastomer

---

[Encapsulation] Encapsulation compound

Flame retardants (PFBS, Al(OH)₃, Triphenylphosphate, Red Phosphorous, Melamine Cyanurate)

(additive)

---

[Encapsulation] Flame-retardant additives and fillers used in housing/potting systems:

• PFBS (perfluorobutane sulfonate)

• Al(OH)₃ (Aluminium hydroxide)

• Triphenylphosphate

• Red Phosphorous

• Melamine Cyanurate

Inorganic additives / fillers (Zeolite, Silica/Quartz, Aluminium powder)

(inorganic additive / filler)

---

[Encapsulation] Mineral additives in polymer compounds:

• Zeolite (aluminosilicate)

• Silica / Quartz

• Aluminium powder

PTFE

(filler)

---

[Encapsulation] PTFE modifier in LCP housing compound

Silver (Ag)

Heavy / Noble Metal

---

[Termination] Termination main compound with noble metal in some variant (Ag/Pd/Pt)

Palladium * (Pd)

Heavy / Noble Metal

---

[Termination] Termination compound with noble metal in some variant (Ag/Pd/Pt)

Platinum * (Pt)

Heavy / Noble Metal

---

[Termination] Termination compound with noble metal in some variant (Ag/Pd/Pt)

Zinc (Zn)

Heavy Metal

---

[Termination] Compound in Cu-Ni-Zn termination

Gold * (Au)

Heavy / Noble Metal

[Termination] Precious/refractory metal termination systems on some variant

Tungsten ** (W)

Heavy / Noble Metal

[Termination] Precious/refractory metal termination systems on some variant

Chromium (Cr)

Metal

Opt.

[Active Part] Alloying elements in soft-magnetic composite Fe-Cr-Si powder core

Silicon * (Si)

Metal

Opt.

[Active Part] Alloying elements in soft-magnetic composite Fe-Cr-Si powder core

FR4 board

Composite

Opt.

[Encapsulation] Mechanical elements in encapsulation

PVC

Elastomer

Opt.

[Encapsulation] PVC sheathing on wire/lead insulation

Bismuth * (Bi)

Heavy Metal

Opt.

[Termination] Bi 3 wt% in Sn97/Bi3 lead-free solder finish