RoHS Compliance in Magnetic Components: What Buyers Need to Know

What Is RoHS?

RoHS stands for "Restriction of Hazardous Substances." It is a European Union directive (originally 2002/95/EC, recast as 2011/65/EU and amended by 2015/863) that restricts the use of specific hazardous materials found in electrical and electronic equipment. While it originated in the EU, RoHS compliance has become a de facto global standard, with similar regulations adopted in China, South Korea, Japan, India, Turkey, and other markets.

For buyers of magnetic components (inductors, transformers, chokes, and current sensing devices), RoHS compliance means that every material in the finished component, from the magnetic core to the wire insulation to the solder on the leads, must meet the restriction limits.

Restricted Substances

The current RoHS directive (RoHS 3, incorporating the 2015 amendment) restricts ten substances in electrical and electronic equipment:

Substance	Maximum Concentration	Where It Appears in Magnetics
Lead (Pb)	0.1% (1000 ppm)	Solder, lead terminations, brass hardware
Mercury (Hg)	0.1% (1000 ppm)	Rarely an issue in magnetics
Cadmium (Cd)	0.01% (100 ppm)	Older plating processes, some pigments
Hexavalent Chromium (Cr6+)	0.1% (1000 ppm)	Some corrosion-resistant coatings
PBB (Polybrominated biphenyls)	0.1% (1000 ppm)	Some flame retardants in bobbins/housings
PBDE (Polybrominated diphenyl ethers)	0.1% (1000 ppm)	Some flame retardants in plastic components
DEHP (Bis(2-ethylhexyl) phthalate)	0.1% (1000 ppm)	Flexible PVC insulation, some tapes
BBP (Butyl benzyl phthalate)	0.1% (1000 ppm)	Some adhesives and coatings
DBP (Dibutyl phthalate)	0.1% (1000 ppm)	Some adhesives and sealants
DIBP (Diisobutyl phthalate)	0.1% (1000 ppm)	Some plasticizers in wire coatings

The concentration limits are measured per homogeneous material, meaning each distinct material in the component is evaluated separately. For example, the solder on the leads is one homogeneous material, the copper conductor is another, and the enamel insulation is another. Each must independently meet the limits.

Why RoHS Matters for Magnetic Components

Magnetic components contain multiple materials that historically included restricted substances. Understanding where these substances appeared (and what replaced them) helps buyers ask the right questions.

Lead in Solder

The most significant change RoHS brought to magnetic component manufacturing was the elimination of traditional tin-lead solder (typically 63% tin, 37% lead). For decades, Sn63/Pb37 was the industry standard for tinning inductor leads and terminating wire connections. RoHS required a transition to lead-free alternatives.

The most widely adopted lead-free solder for magnetic component terminations is SN100 (also called SN100C), which is 99.3% tin with 0.7% copper and trace amounts of nickel. SN100 provides good wetting, reliable joints, and compatibility with standard soldering processes. Other lead-free alloys used in the industry include SAC305 (96.5% tin, 3% silver, 0.5% copper) and SN100CL.

Core Materials

The magnetic core materials commonly used in inductors and transformers (ferrite, silicon-iron, permalloy, powdered iron) are inherently RoHS compliant. These are inorganic metallic alloys or ceramic compositions that do not contain restricted organic substances or heavy metals at levels exceeding the thresholds.

Core coatings require attention. Epoxy and powder coatings used on tape-wound cores must be verified as RoHS compliant. Reputable core suppliers provide material declarations confirming compliance.

Wire and Insulation

Copper magnet wire with enamel insulation is inherently RoHS compliant. The copper conductor contains no restricted substances, and modern enamel formulations (polyurethane, polyester, polyamide-imide) are free of restricted substances. The four phthalates added in the 2015 amendment (DEHP, BBP, DBP, DIBP) are the main concern for flexible insulation materials, but standard enamel magnet wire formulations do not use these plasticizers.

Nickel wire is similarly compliant. The nickel conductor and its insulation do not contain restricted substances.

Insulation Tape and Adhesives

Polyester film tapes (such as Mylar) used for core insulation and winding layer insulation are generally RoHS compliant. The adhesive layer on pressure-sensitive tapes should be verified, as some older adhesive formulations contained phthalates. Major tape manufacturers (3M, Tesa, Nitto Denko) provide RoHS declarations for their products.

Documentation Requirements

RoHS compliance is only as good as the documentation that supports it. Buyers should understand what documentation to expect and what to request from their suppliers.

Declaration of Conformity

A Declaration of Conformity (DoC) is a document in which the manufacturer declares that the product meets the requirements of the RoHS directive. For magnetic components, this typically takes the form of a letter or certificate stating that the specific part number(s) comply with EU Directive 2011/65/EU as amended by 2015/863/EU. The declaration should identify:

• The specific part number(s) covered
• The directive and amendment referenced
• The date of the declaration
• The name and position of the person making the declaration
• The company name and address

Material Declarations

For detailed compliance verification, material declarations break down the component into its constituent materials and confirm that each one meets the restriction limits. The most common format is the IPC-1752A material declaration standard, which provides a structured framework for reporting substance content. Some customers use the REACH SVHC (Substances of Very High Concern) reporting format, which covers a broader list of substances beyond RoHS.

Test Reports

Third-party test reports from accredited laboratories (such as SGS, Bureau Veritas, Intertek, or TUV) provide the highest level of assurance. These reports document XRF (X-ray fluorescence) screening or wet chemistry analysis of each homogeneous material in the component. While third-party testing is typically performed on a periodic basis (annually or when materials change) rather than on every production lot, having current test reports on file demonstrates a robust compliance program.

How to Verify Your Supplier's Compliance

Asking "Are you RoHS compliant?" is necessary, but it is the starting point for verification. Here is a more thorough approach:

Questions to Ask

1. What solder alloy do you use for lead tinning? The answer should be a specific alloy (SN100, SAC305, or equivalent lead-free formulation), along with the supplier name.
2. Can you provide a Declaration of Conformity for this part number? This should be a signed document referencing the specific directive.
3. Do you have material declarations (IPC-1752A or equivalent) available? This shows they have documented the material composition at the component level.
4. Do you have third-party test reports (XRF or wet chemistry) for any of the materials? This demonstrates analytical verification beyond self-declaration.
5. How do you control incoming materials for RoHS compliance? Look for a process that includes requiring RoHS declarations from their own suppliers and periodic verification.
6. What happens when you change a material or supplier? A robust compliance program re-verifies RoHS status whenever materials change.
7. Are you compliant with the four phthalates added in 2015 (DEHP, BBP, DBP, DIBP)? Some suppliers may have compliance documentation that predates the 2015 amendment and does not cover these substances.

Common Compliance Pitfalls

Legacy Components

If you are sourcing replacement components for existing designs, be aware that the original parts may have been manufactured before RoHS. The replacement parts should be RoHS compliant, but verify that the lead-free solder is compatible with your assembly process. Lead-free solder requires higher reflow or wave soldering temperatures, which may affect other components on the board.

Mixed Assemblies

A magnetic component may be RoHS compliant, but if it is soldered to a PCB using leaded solder, the assembly is not compliant. RoHS applies to the entire finished product, meaning every component and every process material (solder paste, flux, conformal coating) must meet the restrictions.

Exemptions

The RoHS directive includes specific exemptions for applications where technically viable alternatives do not yet exist. For magnetic components, the most relevant exemptions include:

• Exemption 6(a): Lead in high-melting-temperature solders (lead content >85%). This exemption applies to some internal connections in specialized transformers but is being phased down.
• Exemption 6(b): Lead in solders for servers, storage, and storage array systems. Narrowly applicable.
• Exemption 6(c): Lead in solders for network infrastructure equipment. Narrowly applicable.
• Exemption 7(a): Lead in high-temperature glass. May apply to some hermetic seals in military/aerospace transformers.

For standard commercial and industrial inductors and transformers, these exemptions are rarely invoked. The technology to manufacture fully RoHS-compliant magnetic components is mature and well-established.

Beyond RoHS: REACH and Other Regulations

RoHS is one piece of a broader regulatory landscape. Buyers should be aware of these related requirements:

REACH (EU Regulation 1907/2006)

REACH (Registration, Evaluation, Authorization, and Restriction of Chemicals) is a comprehensive EU chemicals regulation that covers a much wider range of substances than RoHS. Under REACH, suppliers must communicate information about Substances of Very High Concern (SVHC) present above 0.1% in their products. The SVHC Candidate List is updated regularly and currently contains over 230 substances. While most magnetic component materials are not affected, buyers increasingly request REACH declarations alongside RoHS documentation.

California Proposition 65

For products sold in California, Proposition 65 requires warnings for products containing chemicals known to cause cancer or reproductive harm. The thresholds and substance list differ from RoHS. Lead, cadmium, and nickel are on the Prop 65 list, and the warning thresholds can be stricter than RoHS limits in some cases.

China RoHS (GB/T 26572-2011)

China's equivalent of the EU RoHS directive restricts the same six original substances (not yet the four phthalates) and applies to electrical and electronic products sold in China. The labeling and marking requirements differ from the EU directive.

Compliance Checklist for Procurement

When sourcing magnetic components, use this checklist to ensure RoHS compliance is properly addressed:

• RFQ specifies "RoHS compliant per EU Directive 2011/65/EU as amended by 2015/863/EU"
• Supplier confirms lead-free solder alloy by name (SN100, SAC305, or equivalent)
• Supplier provides signed Declaration of Conformity referencing specific part numbers
• Declaration covers all ten restricted substances (including four phthalates)
• Material declarations are available for detailed substance-level review
• Supplier has a process for managing material changes and re-verification
• REACH SVHC declaration is available if required by your compliance program
• Incoming inspection includes periodic verification (XRF screening or certificate review)

Summary

RoHS compliance for magnetic components is well-established and straightforward when proper attention is given to material selection and documentation. The key areas to verify are solder composition (lead-free), core coatings, and insulation materials. Requesting specific documentation (DoC, material declarations, test reports) and asking targeted questions about materials and processes will ensure that the components you source meet both the letter and the intent of the regulation.