Watch out for EU RoHS exemptions when evaluating products for China RoHS compliance

By now, the industry understands that China RoHS differs from EU RoHS by allowing any component that is <4mm³ to be treated as a homogeneous material. This covers most SMT passive components, allowing the limit of 1000 ppm to be applied at the component level, not the homogeneous level. However, most EU RoHS compliant SMT resistors contain well in excess of 1000 ppm of lead by weight at the component level, said Sommer.

The lead (Pb) is contained in the lead oxide of the primary glass layer of the resistor body and in the resistive layer. It is not technologically possible to produce SMT resistors without the use of lead in oxide form in various parts of the component, Sommer said, which is the reason behind the exemption for lead in glass of electronic components and electronic ceramic parts.

Sommer also said the common substitution of the term "lead-free" for RoHS compliance is misleading. "Any RoHS-compliant component that claims an exemption for lead is essentially not lead free and will need to be declared for China RoHS."

If EU RoHS certificates of compliance have been used, they need to be assessed to determine if any exemptions have been claimed, Sommer said. Similarly, if full materials disclosures have been used to form the basis of EU RoHS compliance, these need to be re-assessed for China RoHS.

Where else do EU exemptions need to be disclosed for China RoHS?

There are other EU RoHS-compliant components where lead is found in concentrations greater than 1000 ppm. There is an exemption for lead in high-melting type solders containing >85% lead, and for lead as an alloying element in steel to 0.35%, aluminum to 0.4% and copper alloys (including brass) to 4%, said Sommer. (See related article about lead exemptions: EU updates RoHS exemption annex.)

In addition, high-melting type solders are found in many ICs, and if the IC is >4 mm³ then the 1000 ppm applies at the homogeneous level (EIP-A). (See related article with info on EIP-A, EIP-B, EIP-C and China declaration table: Eight steps to China RoHS compliance.)

The exemption for lead as an alloying element is derived from a free machining alloy spec, and any steel, aluminum, copper or brass part that has been machined is likely to contain lead in this form, Sommer said.

Other EU RoHS exemptions that can lead to trouble when evaluating for China RoHS compliance include mercury in backlights for LCD displays and cadmium in switch contacts. All of these will require an "x" in the box of the China RoHS Declaration Table for subassemblies containing these materials.

In addition, if a product is EU RoHS compliant for hexavalent chromium, then the product should not need any boxes with an "x" for Cr6 in the Declaration Table. The exception is Category 3 products that are using the exemption for Cr6 in sheet metal and fasteners, said Sommer. This expires in July 2007. (See related article: TCP replaces hexavalent chromium coatings in enclosures.)

If a product is EU RoHS compliant for polybrominated biphenyls (PBB) and polybrominated diphenyl ethers (PBDE), then the product should not need any boxes with an "x" for PBB or PBDE in the Declaration Table. Deca BDE is the only EU exemption for these substances and section 3.2 of the China RoHS Marking Standard SJ/T11364-2006 specifically excludes Deca BDE from the requirements.

Upshot: If your product is EU RoHS compliant, you should not have to declare any PBB, PBDE or Cr6, said Sommer, but you may need to declare mercury and cadmium, and almost certainly will have to declare lead in printed circuit assemblies (PCAs) and possibly mechanical subassemblies.

What is a declaration table?

To develop a declaration table, products need to be segmented into logical subassemblies, and a good place to start is with the bill of materials (BOM).

At the top level of the BOM, the product should be split into subassemblies, which can be used as the basis for building the declaration table, Sommer said. "If there are multiple similar subassemblies, such as PCAs, these can be grouped together. However, if one PCA contains a hazardous substance that must be declared, such as mercury in a display backlight, then it is advisable to declare this PCA separately."

Once the basic structure of the Declaration Table has been established the BOM needs to be scrubbed for any component that contains one of the hazardous substances that must be declared. Assuming that the product is EU RoHS compliant then this process can be as simple as performing a risk assessment of the BOM or physical product, explained Sommer.

If the product is not EU RoHS compliant, then the material composition data or EU RoHS declaration with declared exemptions, or China RoHS Declarations for each component need to be sourced.

When populating the Declaration Table, once the first component in a subassembly has been found with a hazardous substance that must be declared, then an "x" is required in the appropriate box. There is no requirement to disclose the actual amount of substance in a subassembly, Sommer said. Click here for a sample declaration table template.