Your customer’s quality team asks for a material certificate and a RoHS declaration for a part you buy in Vietnam. You email the supplier and the reply does not quite answer the question. A week later you are still waiting.
The obstacle is rarely language. Most of the documents buyers ask for are not issued by the factory that makes the part. They are issued upstream — by the steel mill, the resin producer, the plating chemical supplier — and the factory can only pass them on if it kept them, for the right lot, at the time it bought the material. Ask after production and the factory first has to work out which delivery of material went into your parts. This article sets out who issues what, when to make each document a condition, the names that work in English, and what to do when a document cannot be produced.
💬 Need a document list built into your next enquiry? Send us the part and your customer’s requirement and we will help you write it so it is priced in from the start.
Who issues each document decides how hard it is to get
The difficulty of obtaining a document depends not on its type but on who issues it; the further upstream the issuer, the earlier you must ask.
Documents the parts factory issues itself: dimensional and visual inspection reports, declarations of conformity, process records.
Documents only the material source can issue: steel inspection certificates, resin data sheets and safety data sheets, composition information for plating chemicals and paints. The factory is a relay for these. Material arrives in lots at different times, so if you ask after the event, the factory has to trace which lot was used before it can even ask its supplier.
| Part type | Documents usually needed | Actual issuer | Watch for |
|---|---|---|---|
| Machined, stamped or cast metal parts | Material inspection certificate; dimensional inspection report | Certificate: steel mill or stockist. Report: the factory | Link material lots to part lots |
| Moulded plastic parts | Resin data sheet, safety data sheet, inspection report | Resin producer for the first two; moulder for the report | A grade change changes every document |
| Electronic parts and assemblies | Substance content information, RoHS declaration | Component makers hold the source data; the assembler compiles it | Any substitute component needs new data |
| Surface treatment and heat treatment | Process specification, thickness or hardness records, chemical information | The treatment shop; chemical data from the chemical supplier | Often done by a second-tier subcontractor |
When to ask for what: quotation, first article, production
A document is priced and planned only if the enquiry states four things about it — type, language and format, frequency, and deadline.
“Please provide certificates” does not do this. Write which document for which part number, in which language and format, how often (first delivery only, every lot, annual renewal) and by when. Frequency is the item most often missed, and the second shipment is where the argument starts.
| Quotation stage | First article | Production lots | |
|---|---|---|---|
| Purpose | Confirm what can be issued and at what cost | Prove the part can be made to specification | Monitor variation between lots |
| What to ask for | Examples of the supplier’s documents and formats | Material certificate, report on all or nearly all characteristics | Report on critical characteristics |
| Frequency | Once | Before production starts; after any design change | Every lot or at an agreed interval |
| On any change | Written into the contract | New submission if material, process or subcontractor changes | Back to first-article level |
The single most useful line is “any change of material, process or subcontractor returns the part to first-article approval”, agreed in writing. How the first-article sample connects to inspection is covered in sample approval stages and pre-shipment inspection and AQL.
Material certificates under EN 10204
For metal parts, name the EN 10204 certificate type on the order; only a type 3.1 or 3.2 certificate reports results for the material actually delivered.
| Type | Document | Who validates it | Test results? | Basis |
|---|---|---|---|---|
| 2.1 | Declaration of compliance with the order | Manufacturer | No | Manufacturer’s statement only |
| 2.2 | Test report | Manufacturer | Yes | Non-specific — routine testing, not necessarily the delivered product |
| 3.1 | Inspection certificate 3.1 | Manufacturer’s inspection representative, independent of manufacturing | Yes | Specific — the delivered product or its test unit |
| 3.2 | Inspection certificate 3.2 | As 3.1, countersigned by the purchaser’s inspector or an inspector designated by regulation | Yes | Specific |
A 2.1 document carries no measured values, and the values on a 2.2 report do not come from your delivery. If you need actual values, specify 3.1 or higher, and agree separately how material lot numbers are linked to part lots. The international counterpart is ISO 10474; Japanese suppliers may refer to JIS G 0415, which is close to ISO 10474 but not identical. Name the standard and the type you want.
💬 Writing the document requirements in English and Vietnamese, chasing them and checking what comes back is part of how we run sourcing from Vietnam.
Names that work in English
Use the document names an international supplier will recognise, and be precise about which ones carry measured values.
- Material inspection certificate — Mill Test Report (MTR), Mill Test Certificate, Inspection Certificate 3.1. “Mill sheet” is a Japanese usage and is often not understood.
- Inspection report — dimensional and visual results from the factory’s own inspection.
- Certificate of Conformance (CoC) — a statement of compliance. It carries no measured values.
- Certificate of Analysis (CoA) — measured values for a specific lot.
- Material Data Sheet — typical properties of a grade, not of a lot.
- Safety Data Sheet (SDS) — hazard and handling information for a substance or mixture.
- Declaration of conformity / declaration of non-use — for restricted substances such as RoHS.
Name the regulation formally too. RoHS is Directive 2011/65/EU; Delegated Directive (EU) 2015/863 added four phthalates, bringing the restricted list to ten substances, with the phthalate restrictions applying from 22 July 2019. REACH is Regulation (EC) No 1907/2006; where an article contains a substance on the candidate list of substances of very high concern above 0.1% by weight, information must be passed down the supply chain.
| Substance | Maximum concentration in homogeneous material | Basis |
|---|---|---|
| Lead, mercury, hexavalent chromium | 0.1% each | Directive 2011/65/EU, Annex II |
| PBB and PBDE flame retardants | 0.1% each | Directive 2011/65/EU, Annex II |
| Cadmium | 0.01% | Directive 2011/65/EU, Annex II |
| DEHP, BBP, DBP, DIBP phthalates | 0.1% each | Delegated Directive (EU) 2015/863 |
The limits apply per homogeneous material — a plating layer, a resin, a solder — not to the whole part, so a meaningful declaration rests on material-by-material data.
When a document “cannot be provided”
Before accepting “not possible”, try three things in order: go to the issuer, use an accredited laboratory, and secure the point in the purchase order.
(a) Go back to the issuer. The factory may not hold the certificate while its material supplier does. Ask for the material lot number and the supplier’s name, and request the document from there.
(b) Use an accredited laboratory. Vietnam has laboratories accredited to ISO/IEC 17025 under the national accreditation body, the Bureau of Accreditation (BoA), whose laboratory scheme is known as VILAS; a test report issued under accreditation carries the VILAS number. BoA is a signatory to the ILAC mutual recognition arrangement, which is what allows accredited results to be recognised elsewhere. Check that the specific test method is within the laboratory’s accredited scope.
(c) Secure it in the purchase order. State the grade, the standard and the treatment specification, and agree what happens if the delivered material differs. Be careful with equivalence: Vietnam’s national standards (TCVN) sit under the Ministry of Science and Technology, and whether a TCVN grade can be treated as equivalent to a JIS, ASTM or EN grade needs a documented basis. Agree the applicable standard in writing rather than building your own cross-reference.
A laboratory report proves what a sample measured; it does not prove where the material came from or which lot it belongs to. If your customer requires traceability, a test report is not a full substitute for the mill’s certificate.
Where these documents fit in the order
Documents are part of the specification, so they belong in the enquiry, the purchase order and the inspection plan — not in a follow-up email.
Process-specific additions are covered in the articles on each process: test bars for iron castings in iron castings from Vietnam, melt composition for aluminium die castings, coil traceability and thickness records in sheet metal and stamping, and resin data and substitution in injection moulding in Vietnam.
💬 We find, vet and manage the Vietnamese supplier for each part, and check that it can actually issue what your customer needs before you order. Tell us what is required.
Frequently asked questions
1. Can I ask for a material certificate after the order?
You can, but the issuer is the material producer, so the factory first has to identify which lot went into your parts. Make it a condition at the quotation stage.
2. Is a Certificate of Conformance enough?
It states compliance but contains no measured values. If your customer needs values, ask for an inspection certificate 3.1 for material or a Certificate of Analysis for a specific lot.
3. Can TCVN grades be treated as JIS or ASTM grades?
Not automatically. Agree the applicable standard and grade with the supplier in writing, with the basis for any equivalence.
4. What is the difference between a RoHS declaration and a substance-content data file?
A RoHS declaration states compliance with Directive 2011/65/EU. A substance-content file lists what the part contains so your customer can assess it against several regulations. If your customer prescribes a format, use it.
5. Can a third-party test replace a mill certificate?
A test report shows what a sample measured, not where the material came from or its lot history. Where traceability is required, it is not a full substitute.
Sources: EN 10204:2004; ISO 10474; Directive 2011/65/EU, Annex II; Delegated Directive (EU) 2015/863; Regulation (EC) No 1907/2006; ISO/IEC 17025; ILAC MRA. Checked on 17 October 2026.