RoHS – Homogeneous Material

The RoHS Directive (Restriction of Hazardous Substances) establishes limits for hazardous substances in electrical and electronic equipment (EEE). A core principle of this regulation is that limit values always apply per homogeneous material, rather than for an entire component or product. What does "homogeneous material" mean?

A homogeneous material is defined as a material of uniform composition throughout that cannot be mechanically disjointed into different materials (e.g., a plastic layer, a solder joint, or a metal alloy).

Practical example: A cable consists of several homogeneous materials – copper conductors, PVC sheathing, and solder. Compliance with RoHS limit values (e.g., max. 0.1% lead) must be verified for each individual material. Calculating an average value across the entire cable is strictly prohibited. Why is this important?

Accurate identification of homogeneous materials is critical for:

- Bills of Materials (BoM): Every material layer must be systematically documented. - Supplier Audits: Suppliers must provide evidence of conformity for each homogeneous material. - Product Design: RoHS-compliant materials must be selected at the earliest stages of development. Companies seeking to automate RoHS compliance benefit from tools like turnus.ai, which structured BoMs and track compliance documentation down to the homogeneous material level – eliminating manual Excel maintenance.