Electronics Guide

The Homogeneous Material Hierarchy

Substance restrictions in electronics apply at the level of the homogeneous material—a material that cannot be separated into different materials by mechanical means such as unscrewing, cutting, crushing, grinding, or abrasion. A declaration format must therefore be able to express a nested structure: a product contains subassemblies, which contain components, which contain materials, which contain substances. A resistor declaration might report a ceramic substrate, a resistive film, a nickel barrier layer, a tin termination, and an epoxy coating as separate homogeneous materials, each with its own substance breakdown and its own mass.

The hierarchy matters because dilution is not permitted. A lead-bearing brass contact of two hundred milligrams inside a two-kilogram instrument fails the RoHS threshold on the mass of the brass, not on the mass of the instrument. Declaration formats that report only at the product level cannot answer the compliance question at all; they can only carry a supplier's conclusion about it.

Thresholds, Intent, and Impurities

Each declarable substance carries a reporting rule. The most common is a concentration threshold of 0.1 percent by weight, or one thousand parts per million, in the homogeneous material, which mirrors the RoHS and REACH Article 33 thresholds. Cadmium under RoHS uses 0.01 percent. Some entries require reporting whenever the substance is intentionally added, regardless of concentration, because the regulatory question concerns deliberate use rather than trace presence.

The distinction between an intentionally added substance and an unavoidable impurity is a frequent source of dispute. A supplier may legitimately omit a trace metal that arrives as an ore contaminant while another supplier of the same material reports it, producing two declarations that disagree without either being false. Well-written requests state explicitly whether trace impurities must be reported and at what level, rather than leaving the supplier to guess.

The Standard and Its Database

IEC 62474 is unusual among IEC standards in that most of its operative content lives outside the published document. The standard specifies the procedure, the required content, and the form of a declaration, then delegates the substance lists and the exchange schema to an associated online database. That separation is deliberate. Substance regulation changes several times a year; an IEC standard is revised on a cycle measured in years. Placing the volatile content in a database allows the list to track regulatory change without reopening the standard.

The database holds several linked datasets:

• Declarable substance groups and declarable substances: the reporting list itself, defining what must be declared and under what condition.
• Reference substances: individual substances, identified by CAS Registry Number, that belong to a declarable substance group. A group such as short-chain chlorinated paraffins covers many individual compounds; the reference substance list makes the membership explicit so that software can resolve a specific CAS number to the group that governs it.
• Material classes: a controlled vocabulary for describing materials, so that declarations can be aggregated and compared across suppliers.
• Exemptions: the applicable regulatory exemptions a supplier may cite, in coded form rather than free text.
• Query list: standardized questions a customer may ask beyond composition, such as whether a part falls within a named regulation's scope.
• XML schema: the machine-readable format in which declarations are exchanged.

The database is revised as needed and at least once per year; in practice it moves shortly after each update to the REACH candidate list. Each release carries a sequential version designation in the form D28.00, and a declaration is meaningful only in relation to the version it was assessed against. Programs that fail to record that version discover the problem the first time a substance is added: they cannot distinguish a part that was checked against the new list from one whose declaration predates it.

The Declarable Substance List

The declarable substance list, universally abbreviated DSL, is the consolidated reporting list for the electrotechnical industry. It carries on the order of two hundred substances and substance groups that may plausibly appear in electrotechnical products above a reporting threshold. Entries qualify for inclusion on one of two grounds: the substance is subject to a legal requirement in a significant market, or the industry has agreed that it warrants reporting for reasons of global interest even where no law yet compels it.

The regulatory sources feeding the list include the EU RoHS Directive, the REACH candidate list and authorization and restriction annexes, the EU Persistent Organic Pollutants Regulation, and comparable instruments in other jurisdictions. The list is therefore broader than any single regulation and narrower than the universe of chemistry; it represents the intersection of what is regulated somewhere and what actually turns up in electronics.

Consolidation is the point. Without a shared list, a supplier serving customers in the European Union, the United States, Japan, China, and Korea would maintain a separate reporting scope for each. The DSL lets that supplier assess a part once and answer everyone, and it lets the customer interpret the answer without knowing which regulatory tradition the supplier follows.

The list also has a lineage worth knowing. Its predecessor was JIG-101, the Joint Industry Guide Material Composition Declaration for Electronic Products, published in 2005 by the Electronic Industries Alliance, the Japan Green Procurement Survey Standardization Initiative, and JEDEC. JIG-101 established the practice of a shared industry disclosure list, reached edition 4.1, and is no longer maintained. References to it in other standards have been redirected to IEC 62474. Legacy declarations citing JIG-101 still circulate in long-lived product records, and they should be treated as snapshots of a list that stopped tracking regulation more than a decade ago.

The Exchange Format

IEC 62474 defines an XML schema for declarations, which is what makes automated processing possible. A conforming file identifies the declaring organization, the item declared, the declaration's validity and revision, the list version applied, and the composition or compliance content itself. Because the schema is standardized, a compliance data system can validate structure, resolve substance identifiers, and roll composition up a bill of materials without human transcription.

The schema's reach extends beyond IEC 62474 itself. Japan's chemSHERPA scheme adopted it as the data format for both articles and chemical products, which means a single parser handles declarations from two of the industry's major reporting regimes.

IPC-1751 and the Common Header

IPC-1751, Generic Requirements for Declaration Process Management, defines the administrative content shared by every declaration in the family: who is requesting, who is responding, which items are covered, what authority the signer holds, and how revisions are identified. Factoring this out means that a laboratory report, a materials declaration, and a minerals disclosure carry the same identifying data in the same fields, so that a single system can file them against the same part record.

Declaration Classes in IPC-1752A

IPC-1752A, Materials Declaration Management Standard, was published in 2010 and remained the industry's working format until the B revision replaced it a decade later. Its defining feature is a graded set of four declaration classes, which let a request specify how much detail the answer requires. Class A is a response to a standardized query list, stating compliance with named regulations without reporting any substance data. Class B reports content by material class. Class C reports declarable substances at the product level. Class D reports composition at the homogeneous material level and is the form used for full material disclosure.

Grading the request is what makes large-scale collection affordable. A passive component available in a catalog with a published compliance statement does not warrant the same effort as a custom molded housing whose colorant, flame retardant, and mold release are all unknown. A program that demands Class D from every supplier will collect less usable data than one that asks for the class each part actually justifies, because suppliers with limited compliance staff respond to the demands they can meet.

The standard was amended three times, and Amendment 3 is the one that mattered most to software. It introduced a five-digit identity code for each declarable substance and substance group, together with a defined list of coded statements for Class A query responses. Before that, tools matched entries by parsing the substance name, and the name of a substance group may run to several hundred characters, so a difference in spelling, transliteration, or punctuation between two suppliers was enough to make an otherwise valid file fail to load.

IPC-1752B and Later Revisions

IPC published IPC-1752B in July 2020, a major revision that is not backward compatible with earlier versions. Two changes matter operationally. The revision added data fields aligned with the European Chemicals Agency's SCIP database, so that the information a supplier already provides for customer compliance can feed the mandatory notification of substances of concern in articles rather than being re-entered by hand. It also allowed a single XML file to carry different declaration classes for different products, which suits a supplier reporting a catalog in one transmission where some parts have full disclosure and others do not.

IPC-1752C followed in June 2026, alongside revised editions of several sibling standards. The change with the longest reach is not confined to any one document: from 2026 onward, new and revised IPC-175x standards are supported by JSON schemas, while standards published before that date remain XML-based until they are revised. Toolchains built on the XML schema therefore face a migration, and a declaration archive will hold both encodings for years. All three revisions of IPC-1752 remain in concurrent use, so a program that receives supplier data must expect to parse more than one of them long after any new release.

The Rest of the Family

The remaining IPC-175x standards extend the same transactional model to adjacent disclosures:

• IPC-1753, Laboratory Declaration Standard: structures analytical test results so that laboratory data can be attached to a part record and compared across laboratories rather than circulating as unstructured reports.
• IPC-1754, Materials Declaration Standard for Aerospace and Defense and Other Industries: extends materials declaration for programs with long sustainment horizons and deep supply chains, where a reporting obligation may outlive the part's production by decades. See Diminishing Manufacturing Sources for the obsolescence problem this addresses.
• IPC-1755, Responsible Sourcing of Minerals Data Exchange Standard: carries smelter and country-of-origin disclosures for conflict-affected minerals, a subject treated in Conflict Minerals and Ethical Sourcing.
• IPC-1756, Manufacturing Process Data Management: conveys process information such as finishes, thermal profiles, and packaging conditions that bear on both compliance and reliability.
• IPC-1757, Process Chemicals Declaration Standard: covers chemicals consumed in manufacturing rather than incorporated in the product, which matter for worker exposure and emissions even when no substance reaches the finished article.
• IPC-1758, Declaration Requirements for Shipping, Pack, and Packing Materials: addresses packaging composition, which falls under its own restrictions on heavy metals and, increasingly, on recycled content.

The family is unevenly maintained, and the dates show it. IPC-1751, IPC-1752, IPC-1753, IPC-1755, and IPC-1757 were all revised or amended in 2026, while IPC-1756 dates from 2010 and IPC-1758 from 2012 and both still reflect the practice of that period. A program adopting the family should confirm which revision its trading partners actually implement rather than assume the most recent one.

chemSHERPA

chemSHERPA is the Japanese scheme for communicating chemical content through supply chains, developed under Japan's Ministry of Economy, Trade and Industry and maintained by the Joint Article Management Promotion-consortium. It replaced the earlier JAMP formats known as AIS and MSDSplus. Two variants exist: chemSHERPA-AI for articles and chemSHERPA-CI for chemical products. Both adopt the IEC 62474 XML schema, and the declarable substance content derives from the IEC 62474 list, so the scheme is a regional implementation rather than a competing standard. The consortium maintains its own versioned declarable substance list, kept in step with the IEC 62474 database, and releases updated data-entry tools with each revision, so a Japanese customer's request names a chemSHERPA list version much as a European one names an IEC 62474 version. Those tools are distributed free of charge, which lowered the barrier for small suppliers considerably.

IMDS and GADSL

The automotive industry runs a separate and older system. The International Material Data System is a hosted database in which suppliers build material data sheets that reference their own suppliers' entries, so that composition is assembled by linking rather than by resubmitting. Its reporting scope comes from the Global Automotive Declarable Substance List, revised annually by a stakeholder group spanning vehicle manufacturers, suppliers, and chemical producers.

Electronics companies encounter IMDS whenever their parts enter vehicles, and the encounter is rarely painless. The data model, the substance list, and the confidentiality rules all differ from IEC 62474 practice, and a declaration prepared for one system does not transfer cleanly to the other. Suppliers serving both markets generally maintain composition data in a system that can emit either format rather than treating one as the master.

Hosted Declaration Databases

Several hosted services, including BOMcheck and Compliance Data Exchange, sit between the standards and the supply chain. A supplier maintains one substance record per part in the service, and participating customers draw from it rather than issuing individual requests. The arrangement reduces duplicated effort substantially and is common in the medical device sector, where the customer base is fragmented and the parts are long-lived. It also introduces a dependency: the data lives in a third-party system, and access to it usually depends on a continuing subscription, which is a poor foundation for records that must be retained for a decade after a product leaves the market.

Cross-sector harmonization work continues. The Proactive Alliance, a European initiative drawing participants from multiple manufacturing sectors, has pressed for a common material reporting approach that would spare suppliers the burden of maintaining parallel disclosures for each industry they serve.

The Case for Full Disclosure

A compliance statement answers one question at one moment: does this part meet the named regulations as they stand today? When the REACH candidate list gains entries, as it does roughly twice a year, every compliance statement in the archive becomes silent on the new substances, and the only remedy is to survey the supply base again. Organizations that hold full disclosure data instead run a query. The difference between hours and months is decisive when a regulation carries a short transition period, and it is most decisive precisely where re-surveying is hardest: obsolete parts still shipping from service inventory, whose original suppliers may no longer exist.

Full disclosure also supports work that has nothing to do with substance restriction. Recyclers use it to anticipate what a returned product contains. Lifecycle assessment practitioners use it to build inventories without estimating composition. Digital product passport schemes, examined in Digital Product Passports, assume composition data of roughly this depth will exist and will follow the product.

Why Suppliers Resist

Resistance to full disclosure is not obstinacy. A formulation is often the supplier's principal intellectual property, and disclosing every constituent of a proprietary adhesive, laminate resin, or magnet alloy at full precision hands a competitor the recipe. Declaration standards accommodate this partially by permitting confidential constituents to be aggregated under a generic entry up to a bounded fraction of the material, which preserves the mass balance and the assurance that nothing declarable hides in the remainder while withholding the formulation itself.

The second obstacle is simple capability. A supplier cannot disclose what its own suppliers will not tell it, and the difficulty compounds with each tier. A tier-one connector maker may hold complete data for its own molding and plating and none at all for a purchased seal. Requests that ignore this arrive at a wall several tiers up, and the honest answer—that the data does not exist anywhere—is rarely the answer that comes back.

Most programs therefore adopt a graded strategy: full disclosure for custom parts, materials, and high-risk chemistries such as plastics, coatings, and adhesives; compliance declarations for catalog components from suppliers with published compliance programs; and analytical testing where a declaration is unavailable and the risk warrants the expense. The grading should be documented and reviewed, because the risk profile of a part changes when a regulation changes.

Rolling Up a Bill of Materials

Declarations describe items; compliance questions concern products. Bridging the two requires rolling composition up the bill of materials, multiplying each part's composition by its quantity and mass, and preserving the homogeneous material structure so that thresholds remain assessable at the correct level. A roll-up that flattens the hierarchy and reports product-level percentages produces numbers that look authoritative and answer nothing.

The roll-up is only as complete as the bill of materials beneath it. Alternate and substitute parts, no-load positions, consumables applied in assembly such as solder paste, flux residue, conformal coating, and adhesive, and the packaging shipped with the product all carry composition that a naive extract from the engineering bill of materials will miss. Bill of Materials Management covers the data discipline that keeps the underlying structure trustworthy.

Collection

Collection begins from the bill of materials, not from a supplier list, because coverage is measured against parts. Requests specify the declaration class required, the list version to assess against, the treatment of trace impurities, and a response deadline. Substance requirements belong in purchase agreements, where a missing declaration becomes a contractual matter rather than a favor, and supplier qualification should test declaration capability before the first order rather than after the first regulatory question. Supply Chain Compliance covers the wider supplier management framework.

Storage and Retrieval

Declarations must be retrievable years after the engineers who collected them have moved on. The EU technical file supporting a declaration of conformity must be retained for ten years after the last unit is placed on the market, which outlasts many product programs and most software procurement cycles. Storing declarations inside a compliance vendor's platform alone is a hazard; the underlying files and their metadata should also exist in a system the organization controls. Declaration data belongs in the product record alongside the bill of materials, versioned with it, so that a composition query returns the composition of the configuration actually shipped.

Change Management

Three kinds of change invalidate a declaration, and a program must detect all three. A regulatory change adds substances or lowers thresholds, requiring reassessment against a new list version. An engineering change substitutes a part or a material, requiring a new declaration for the new item. A supplier change alters the composition of an unchanged part number, which is the most dangerous case because nothing in the customer's own systems announces it. Guarding against the third requires contractual notification obligations, periodic re-declaration on a defined cycle, and audit sampling, since a supplier that changes a colorant or a plating chemistry without notice will not otherwise be found until a test result contradicts the file.

Common Failure Modes

• Coverage measured by supplier rather than by part: ninety percent of suppliers responding can still leave the highest-risk parts undeclared.
• Free-text answers accepted into structured systems: a scanned letter stating compliance satisfies a checklist and cannot be queried when a new substance is listed.
• Declarations copied forward across revisions: a part revision that changed a plating finish inherits the old declaration unless revision control links the two.
• Silence read as compliance: a supplier that does not answer has not declared anything, yet unanswered requests frequently age out of a tracking system as though resolved.
• Process materials omitted: solder, flux, adhesives, and coatings applied during assembly are part of the finished product and are routinely absent from the declaration set.