Definition#
A homogeneous material is the smallest unit of material that cannot be mechanically separated into different materials by unscrewing, cutting, crushing, grinding or abrasive processes. A coating, a plating layer, the plastic of a connector, or the insulation of a wire are each homogeneous materials.
RoHS limits apply per homogeneous material, not per whole part. That is why composition is reported at fine granularity via a Full Material Declaration.
Why it matters#
RoHS concentration limits (for example 0.1% lead) apply per homogeneous material, not averaged over the whole part. A thin plated layer that is mostly a restricted substance can fail even if its mass is negligible compared to the whole component.
For that reason, composition often has to be reported at fine granularity, for example via a Full Material Declaration.