Plastic material certificates and RoHS: what belongs in the pack

Three different documents, often confused

A moulded part can arrive with a datasheet, a certificate of analysis, a declaration of conformity and a RoHS statement. Buyers often treat them as one pack and file them together, but each answers a different question. The datasheet describes the grade. The certificate of analysis describes a batch. The declaration of conformity states that the part meets a specification or a directive.

The distinction matters when a customer asks for evidence. A datasheet printed from a website cannot show which bag of resin went into which moulding. A RoHS statement that names no grade and no batch cannot be traced to a shipment. The useful pack links the part, the lot and the declaration.

What a practical material pack contains

Start with the grade identity: the supplier name, the commercial grade code, the colour code and the filler content. Add the batch or lot number from the bag or the box, and the date the part was moulded. Without those four items, the rest of the pack cannot be tied to the shipment.

Then add the compliance documents. For an electrical part, that usually means a RoHS declaration, a REACH SVHC statement, and the UL yellow card reference if a flame rating is claimed. If the customer reports to IMDS or a similar database, the material entry is needed as well. A declaration of conformity signs off the part against the drawing and the agreed specification.

• Grade code, colour and filler content
• Resin batch or lot number and moulding date
• RoHS declaration with the directive reference
• REACH SVHC statement, dated and signed
• UL yellow card reference at the rated thickness
• Declaration of conformity against the drawing

What RoHS covers

RoHS restricts the use of ten substances in electrical and electronic equipment: lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls, polybrominated diphenyl ethers, and four phthalates. The maximum concentration is generally 0.1% by weight in a homogeneous material, with a lower limit for cadmium. The directive also allows a limited list of exemptions, which are time limited and should be quoted by number if one is used.

For a plastic housing, the relevant risks are usually pigments, stabilisers, flame retardants and recycled content. A moulder who buys a compounded grade from a reputable supplier is relying on that supplier's declaration. A moulder who adds masterbatch, regrind or a flame retardant from a second source has added a material that also needs a declaration.

The technical documentation that supports a RoHS claim is defined in IEC 63000. It is a file, not a single certificate: it holds the supplier declarations, the material data and the assessment that led to the conclusion. Ask for the declaration and keep the supporting file with it.

REACH and the 0.1% question

REACH is not a ban list in the same way as RoHS. Substances on the candidate list trigger information duties, and those that are added to Annex XIV need authorisation. If an article contains a candidate list substance above 0.1% by weight of the article, the supplier has to give the customer enough information to use it safely, and there are notification duties in some cases.

The threshold is per article, not per homogeneous material, which is where the RoHS and REACH tests differ. A part with several components needs a calculation across the whole article. In practice, the moulder relies on the resin supplier's statement and adds the other materials in the assembly.

REACH declarations should be dated and should name the candidate list version they were checked against, because the list changes. A declaration from three years ago is a record of the past, not a statement about today.

Traceability from bag to box

Traceability is what turns a certificate into evidence. Record the resin batch, the masterbatch batch, the regrind percentage and the moulding date against the production lot. If the part is moulded across several shifts, record which lot went into which box. A customer who finds a problem needs to know what else was made from the same material.

Regrind is the weak point. A moulder may add regrind without recording it, and the customer may have specified a maximum. Put the limit on the purchase order, ask for the regrind record, and check that a flame-rated or food-contact part is not being diluted with unverified material.

When the paperwork is missing

A missing declaration is a hold point, not a note for later. Ask the moulder for the grade code and the batch, then go back to the resin supplier for the declaration. If the grade has changed, or the colour has changed, the declaration has to be reissued for the new material, even if the part number has not changed.

Change control closes the loop. A resin substitution, a new masterbatch, a second regrind source or a moved moulding site can all change the compliance position. Require written approval before the change, and update the material record when it is approved.

• Hold the shipment until the declaration matches the batch
• Confirm the grade and colour on the bag, not only on the invoice
• Reissue the declaration after any material or colour change
• Keep the UL card at the thickness actually moulded
• Record regrind percentage and source for every lot