Overview
Lead-free, RoHS compliant, REACH compliant, halogen free, and free of intentionally added lead are different statements with different definitions, scope, dates, evidence, exemptions, and responsibilities. A paste supplier may describe one product as lead free under its own formulation and documentation, but a finished thick-film circuit also includes substrate, conductors, resistors, dielectrics, overglaze, overcoat, terminals, solder, braze, wire, adhesive, plating, components, coating, ink, packaging, and contamination from processing. Substitution can change printing, firing or cure, adhesion, resistance, TCR, solderability, wire bonding, dielectric behavior, migration, corrosion, thermal mismatch, environmental stability, and supply continuity. Legal thresholds are evaluated at the applicable homogeneous-material and product scope, while exemptions and restricted-substance lists change over time and depend on market and equipment category. This guide creates a material-declaration and engineering-qualification workflow; it is not a declaration of conformity. It does not claim that the pictured products, the whole ThickFilmPCB catalog, any factory process, or any unlisted material is lead free, RoHS compliant, or suitable for a particular jurisdiction.
Failure controls
These are review prompts, not evidence that every risk applies or that every test is available.
- A
Treating lead free, RoHS compliant, REACH compliant, no intentionally added lead, and halogen free as equivalent public claims
- B
Using one paste declaration or one tested sample to label the complete circuit, product family, production process, or catalog compliant
- C
Averaging restricted-substance content across unlike materials instead of applying the governing homogeneous-material scope and exemptions
- D
Replacing a paste for documentation reasons without requalifying printing, firing or cure, refires, resistance, adhesion, joining, protection, and environment
- E
Using expired, generic, wrong-revision, wrong-entity, wrong-product, or wrong-market declarations and missing supplier or legal changes
- F
Publishing a compliance badge before responsible legal, evidence, technical, customer, entity, and release approvals are recorded
Engineering review matrix
Each row links a design variable to evidence that can support a drawing or release decision.
| Variable | Control question | Verification route |
|---|---|---|
| Jurisdiction and product scope | Define market, product category, equipment classification, current directive or regulation, amendments, substance list, homogeneous-material rule, exemptions, dates, importer or manufacturer obligations, and customer additions. | Use current official legal text and a responsible compliance review; record edition, effective date, interpretation, and decision. |
| Material bill and traceability | Track every substrate, paste, dielectric, terminal, finish, solder, wire, adhesive, component, coating, ink, process chemical and other in-scope material by supplier, code, revision, lot, and product drawing. | Reconcile purchasing, traveler, assembly, and product records to the approved bill and allowed substitutions. |
| Supplier declaration quality | Require exact product and entity, restricted substances, thresholds or definitions, exemptions, date, revision, authorized issuer, scope, conditions, and change notification. | Review original current documents and reject generic website claims or declarations that do not cover the purchased item. |
| Analytical evidence | Define sample identity, homogeneous-material preparation, method, analytes, calibration, blanks, detection and quantitation limits, uncertainty, laboratory status, result format, and representativeness. | Review the complete report and preserve sample-to-product traceability; never expand one sample result to an untested catalog. |
| Paste and process compatibility | Compare material system, substrate, companion layers, print, dry, firing or cure, atmosphere, thickness, refires, trim, joining, protection, rework, and storage after substitution. | Use current TDS plus process-representative coupons and travelers for the complete revised stack. |
| Electrical and mechanical function | Specify resistance, TCR, isolation, conductor loss, adhesion, solder or bond interface, geometry, thermal mismatch, loads, protection, and drawing acceptance affected by the material change. | Measure the revised construction before and after assembly and representative environmental conditioning with failure analysis. |
| Contamination and segregation | Control storage, containers, tools, screens, mixers, furnaces or ovens, fixtures, rework, solder, cleaners, work sequence, residues, scrap, labels, and cross-contamination risk. | Audit process segregation and use agreed witness or analytical checks where risk analysis requires them. |
| Revision and maintenance | Set document expiry or review date, law and exemption monitoring, supplier-change triggers, alternative materials, quarantine, customer notification, requalification, retention, and approver roles. | Run periodic evidence reconciliation and link every released product statement to current law, bill, suppliers, tests, and decisions. |
Controlled model
Compliance-scope and material-stack model
Track every intentionally selected material and process input in a revision-controlled bill, map each to the applicable legal requirement and evidence, then qualify the complete functional stack. A compliant declaration and a technically compatible circuit are both necessary, but neither proves the other.
w_Pb,h = m_Pb,h / m_hMass fraction of lead within one legally defined homogeneous material h.
- Units
- Dimensionless, commonly expressed as % by weight
- Use boundary
- The legal definition, restricted substance, maximum concentration, exemptions, analytical method, and market must come from the applicable current law and product classification. Do not average unlike materials across a product.
Coverage = N_evidence-linked materials / N_in-scope materialsA project-control ratio showing whether every in-scope bill-of-material entry has current evidence.
- Units
- Dimensionless
- Use boundary
- Coverage measures document linkage, not legal conformity, truth, analytical sufficiency, technical compatibility, or absence of contamination. Evidence quality and scope still require review.
ΔR/R₀ = (R_after substitution or conditioning − R₀)/R₀Normalized electrical change used when qualifying a replacement material or complete revised stack.
- Units
- Dimensionless, commonly % or ppm
- Use boundary
- State measurand, geometry, temperature, load, process, conditioning, recovery, and uncertainty. Electrical retention alone does not prove chemical compliance or interface reliability.
Δε_th ≈ (α_layer − α_substrate)ΔTFirst-order thermal-strain mismatch term for reviewing a changed paste or layer system.
- Units
- Dimensionless strain; α in 1/K; ΔT in K
- Use boundary
- A screening relation only. Real stress depends on material evolution, thickness, modulus, geometry, interfaces, firing or cure, cooling, assembly, and cycling.
Decision comparison
| Decision | Route A | Route B | Verification |
|---|---|---|---|
| Lead-free formulation statement versus legal conformity | A supplier may state that lead is not intentionally added or that a named paste is lead free under its product definition and issue date. | Legal conformity depends on the applicable jurisdiction, equipment and material scope, concentration limits, exemptions, technical documentation, conformity assessment, and responsibilities for the finished product. | Retain the exact supplier statement and date, map it to current legal requirements, and have the responsible compliance authority approve the product-level conclusion. |
| Supplier declaration versus analytical test | A declaration can cover formulation and supply-chain knowledge but may carry conditions, exclusions, expiry, revision, or substance and product boundaries. | Analytical testing observes selected substances in a defined sample using stated preparation, method, detection and uncertainty, but cannot automatically represent other lots, materials, parts, or future changes. | Use a risk-based evidence plan that defines when declarations, full material declarations, test reports, or additional supplier data are required and how each is scoped. |
| Drop-in substitution versus system requalification | A paperwork-only substitution assumes the replacement preserves printing, thermal process, interactions, geometry, electrical function, joining, protection, and environmental response. | A controlled substitution treats the new material as a change to the stack, process, evidence, and product validation, with screening proportional to risk. | Compare current TDS and declarations, run process and functional coupons, evaluate later assembly and environment, and approve a new stack revision before production use. |
- A firing-process peak shown in a paste TDS describes that named material's processing, not a finished product operating-temperature claim and not compliance evidence.
- Preserve supplier document issue, product code, lot or date applicability, exact wording, exceptions, test sample, method, detection limit, and scope; paraphrased badges erase critical boundaries.
Lead-free system control workflow
The order makes assumptions and ownership visible before a result is promoted to a requirement.
- 01
Define the requirement
Record destination market, product category, customer specification, current law and amendments, restricted substances, homogeneous-material scope, exemptions allowed or prohibited, definition of lead free, evidence format, analytical tests, retention, language, and approval responsibility.
- 02
Inventory the complete stack
List substrate, every conductor, resistor, dielectric, overglaze, overcoat, terminal, plating, solder, braze, wire, adhesive, component, coating, ink, cleaning and process input, packaging where in scope, supplier, product code, revision, lot, and substitution rule.
- 03
Map evidence to each material
Collect current supplier declarations, full material declarations, safety or technical data, exemptions, test reports, issue dates, sample and method scope, concentration and detection information, authorized signatures, and change-notification terms. Mark gaps rather than inferring conformity.
- 04
Review technical compatibility
For any candidate replacement, assess printability, rheology, drying, firing or cure, atmosphere, refires, thickness, resistance, TCR, dielectric, adhesion, solder or bond behavior, protection, thermal mismatch, contamination, environment, and compatibility with the other named layers.
- 05
Build and test the revised stack
Process traceable coupons and production-intent assemblies with actual screens, profiles, layer order, trim, joining, cleaning, rework, coating, and environment. Measure drawing-linked functions and obtain chemical or documentary evidence under the approved compliance plan.
- 06
Approve product-specific documentation
Reconcile supplier evidence, analytical results, bill of materials, process controls, exemptions, technical validation, customer requirements, uncertainty, and deviations. Issue only the exact statement approved for the named product, revision, market, date, and legal entity.
- 07
Control ongoing changes
Monitor legislation, exemptions, substance lists, supplier materials and declarations, formulations, sites, process inputs, components, packaging, and customer requirements. Quarantine or reopen affected products before an unreviewed revision enters the released stack.
Reference boundary
Public method sources
These sources support the engineering method and terminology used in this technical guide. They do not establish a ThickFilmPCB material list, capability limit, customer result, certification, or finished-product specification.
- 01EUR-Lex — Directive 2011/65/EU on hazardous substances in EEE
Supports the EU legal framework, manufacturer responsibility, restricted-substance and exemption structure, conformity documentation, and need to use the current consolidated text; it is not legal advice or evidence for any ThickFilmPCB product.
- 02EUR-Lex — consolidated RoHS text applicable 1 July 2026
Supports that exemptions, categories, conditions and expiry dates change and must be reviewed for the actual product and date; it does not establish whether an exemption applies or a material conforms.
- 03Heraeus C2240 Silver/Palladium Conductor technical data sheet
Provides one named supplier's formulation-specific lead-free and compliance wording together with process and property boundaries; that statement applies only to the identified paste and issue, not a complete circuit or ThickFilmPCB catalog.
Inputs for a practical review
Unknown values may be labelled unknown. The review should convert uncertainty into an explicit decision or validation task.
Send Drawings- 01
Destination markets, product and equipment category, customer restricted-substance specification, current legal requirements, exemptions allowed or prohibited, and required definition of lead free
- 02
Complete product bill of materials and process inputs with supplier, product code, revision, lot, substrate, pastes, dielectrics, terminals, solder, wire, adhesives, components, coatings, and packaging scope
- 03
Required supplier declarations, full material declarations, analytical reports, laboratory or method expectations, detection limits, uncertainty, sample plan, retention, language, and declaration format
- 04
Circuit and assembly drawings, material stack, print, firing or cure, refires, trim, protection, joining, cleaning, rework, segregation, cross-contamination, and traceability controls
- 05
Electrical, mechanical, thermal and environmental acceptance affected by substitution: resistance, TCR, isolation, adhesion, solder or bond, geometry, loads, humidity, fluids, cycling, and stability
- 06
Customer approval, legal and technical reviewer, manufacturer or importer responsibilities, deviations, exemption decisions, release entity, product and revision scope, and effective date
- 07
Supplier-change notification, legislation and exemption monitoring, alternate materials, quarantine, requalification, periodic review, records, and customer-notification requirements