'Homogenous': definition under fire.

THERE are loopholes, and then there are Loopholes. And in Europe, there just might be one in the Restriction of Hazardous Substances directive big enough to drive a truck full of lead solder through.

The RoHS is the controversial mandate that establishes limitations on the use of certain hazardous substances ("hazardous" being a relative term, of course). Among the restrictions: New electrical and electronics equipment sold in Europe market after Jan. 1, 2006, cannot contain lead, mercury, cadmium, hexavalent chromium, or other specified substances. (For a copy of the RoHS directive, go to pcdandm.com and click on the Special Reports link.)

Recent word from the U.K., at least, resembles anything but acquiescence. As a just-released report commissioned by the U.K. Department of Trade and Industry points out, the definition of what the directive considers a "homogeneous material" is as grainy as any lead-free alloy.

As PCD&M reported in April ("New Life for Tin-Lead?, p. 10), 11th hour questions have been raised over how the Rolls defines "homogeneous material," a crucial point, because the interpretation could have a profound impact on our readers.

The RoHs says "a maximum concentration value of 0.1% by weight in homogeneous materials for lead ... shall be tolerated. Homogeneous material means a unit that cannot be mechanically disjointed in single materials."

Under the current language, the products that hypothetically could be categorized homogeneous material are broad indeed. To wit: PCB assemblies, components or raw materials. In short, the language creates a loophole sufficiently large that a board containing dozens or more tin-lead leaded packages attached using tin-lead solder could still pass muster.

According to the U.K. paper Electronics Weekly, ERA Technology, a consulting firm contracted by the DTI to study the RoHS, is calling for a "requirement for a clear understanding of how the definition of the maximum concentration values will be interpreted."

A white paper issued May 24 by the European trade group EICTA and signed by four other associations also calls for concrete guidance from the European Commission, to avoid further confusion as the date of implementation nears. But the signatories support a certain classification of homogeneous materials that says that component makers can supply packages with tin-lead leads provided the boards have less than 0.1% tin-lead content post-assembly.

Under EU rules, governments must "bring into force" (implement) the laws and regulations necessary to comply with Rolls before Aug. 13. But the European Parliament is just coming off last month's elections--the results weren't released until mid June--stalling most member states from issuing guidance on RoHS. So with six weeks to go, the matter remains very much in the air.

While this page thinks readers should be preparing for the worst--the complete elimination of lead from electronics--it is of no small satisfaction to know that the bureaucrats that foisted this onerous and unnecessary burden on the industry are also struggling under its weight. And in the end, the winners will be the lawyers, as usual.