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RoHS standards present moving target

Steve Scheiber, Contributing Technical Editor- December 1, 2008

One challenge to ensuring that electronic products conform to industry regulations is that those regulations often seem arbitrary. Just when companies think they have made sufficient plans to conform, the rules change. As a case in point, the European Union is considering revising the RoHS (Restriction of Hazardous Substances) directive so it covers products such as medical devices and industrial-monitoring equipment and also bans many more chemicals from use in electronics products. Unfortunately, according to a white paper recently released by IPC, implementing some of those changes unaltered could cripple the electronics manufacturing industry.

For example, the EU is proposing a ban on halogen-based chemicals such as TBBPA (tetrabromobisphenol[a]), a flame retardant used in PCB (printed-circuit board) laminates in some two-thirds of the electronic appliances worldwide. In its paper, the IPC contends that there is no evidence of harmful effects from the chemical when it is used in the epoxy resins of PCBs and that there is no adequate universal substitute.

The IPC paper also argues that a ban on this material would have significant side effects. Although halogen-free alternatives are available, quantities are limited, and their inclusion would raise manufacturing costs dramatically (see “Costs of TBBPA ban as estimated by the IPC”). Costs aside, these materials have not undergone the rigorous risk assessments that TBBPA has, and the phosphorus and other elements that they contain may turn out to be more toxic than the bromide that they are intended to replace. Some products would not tolerate the substitution at all.

Another of the proposed regulations suggests doing away with “all organic compounds containing chlorine and bromine,” an action that would create even more havoc, according to the IPC. The original RoHS directive banning lead from electronic solder caused considerable pain as the industry scrambled to find a suitable replacement. The new lead-free solders have a higher melting point than their predecessors did and permit much narrower process conditions during PCB manufacture.

The proposed revisions to the directive would aggravate the situation. Plasticizers and wetting agents used in solder include compounds that would fall under the new ban. Most solder fluxes also contain halides, and there are currently no viable alternatives. In addition, the regulation's ambiguous wording could leave manufacturers unsure of whether their processes conform.

The white paper insists that demanding the industry to replace compounds that have endured years of validation for their intended use with untried and untested alternatives risks system failures, with consequences ranging from mild annoyance to the catastrophic result of an avionics or medical electronics failure. See the IPC paper, “The Electronic Interconnection Supply Chain's Response to Öko-Institut's Recommendations for Proposed Revisions to the RoHS Directive.”