Nick Hoo columns | July 04, 2005

RoHS screening: Your questions answered

Nick Hoo is the Laboratory Manager of Soldertec Materials Division which looks at failure and reliability issues with soldering of electronic assemblies and RoHS screening of assemblies and materials. Read Nick Hoo's RoHS FAQ.
Do I need to get my products tested for RoHS compliance?
If you are an assembler of OEM or CEM PCBs, a European manufacturer selling within the EU, or an importer of manufactured product into the EU, you must be able to demonstrate compliance with the Restriction of Hazardous Substances (RoHS) Directive (2002/95/EC) when your finished product is put on the market in the EU.

Which substances are restricted?
Electronic and electrical equipment must not contain more than the maximum permitted levels of lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs).

What is the deadline for compliance?
The requirements of the RoHS Directive comes into force on 1st July 2006. Product put on the market after this date will be required to be compliant.

What are the implications if my product doesn't comply by then?
An enforcement authority may ask to see evidence that a producer has used due diligence and taken reasonable steps to comply with the requirements of the RoHS Directive. Failure to comply could result in the eventual withdrawal of your product from the market.

How can I find out whether my product complies?
If materials declarations or certificates of compliance for each component of your product are not available from your suppliers, or if you have any doubts over the accuracy or completeness of that information, it is advisable to subject your product to a screening test, which measures the concentration of the restricted substances within it.

Can't I simply crush my product and analyse the remains?
This is a popular misconception; unfortunately the process is not so straightforward. Each homogeneous material within each individual part of the product must comply with the RoHS Directive - the housings, cabling, PCBs, components, fixtures and fittings. To detect the restricted substances, one must know which materials are permitted in a given application and which are not, and also where to look for them, since they are sometimes found deep within the sample to be tested.

Which test method is used to perform the analysis?
A variety of analytical techniques must be employed. Non-destructive methods only examine the surface of the sample and may not detect substances below the top few microns. A destructive test allows materials buried below the surface layer to be investigated, confirming how many homogeneous materials are present in the sample. An example of this is a semiconductor that is made of many different homogeneous materials of each of which should be considered individually.

How is a homogeneous material defined by the RoHS directive?
A homogeneous material is defined as any individual material such as a plastic or ceramic or metal, an example would be an insulated wire containing two homogeneous materials, the PVC insulation on insulated copper wire. Any component of a product may contain several different homogeneous materials.

Nick Hoo
Soldertec Global

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