Leaded Copper Alloys Get A New Lease on Life
An extension of the EU exemption known as 6(c) brought relief to the connector industry.
Back in 2015, there was a great gnashing of teeth over concern that the European Union would no longer allow the use of lead in certain types of copper contacts. Contacts that are made on precision-screw machines rely on a small percent (up to 4%) of lead in the material to efficiently produce high-quality contacts. Leaded copper alloys had received a limited exemption when the original Restriction of Hazardous Substances (RoHS) lead-free mandates were implemented in 2003. If the EU exemption known as 6(c) was allowed to expire, the maximum lead content in electrical and electronic contacts would be limited to 0.1% resulting in serious manufacturing problems.
Most connectors today utilize lower-cost stamped and formed contacts, but certain industries, including industrial, military and medical, often use screw-machined contacts. Stamped and formed contacts are fabricated from thin strips of copper alloys that provide the required spring characteristics to insure adequate normal forces. Commonly used alloys such as phosphor bronze and beryllium copper can be formed into complex structures but exhibit somewhat lower conductivity that can limit their use in high-current applications. Screw-machined contacts are fabricated from solid copper wire that can provide higher conductivity and greater mechanical durability; critical features in harsh environments that demand long service life and absolute reliability such as industrial automation.
Manufactures of screw-machined contacts faced the challenge of finding a lead-free alternative copper alloy with the same electrical, mechanical and machineability characteristics. Introduction of a new material could require significant contact design changes, as well as result in increased tooling wear. Serious concerns about higher material cost as well as the testing and documentation required by implementing a new material were expressed. Even if a comparably priced proprietary material would be found, concerns about availability from a single source would continue. Equipment manufacturers were forced to analyze their bill of materials of each product to identify all screw-machined parts and set up a plan for replacement. Manufacturers of military and some medical equipment that use screw-machined contacts were exempted from RoHS mandates.
When we reported on this situation in March of 2015, connector manufacturers were choosing a variety of responses. Large multi-national connector manufacturers typically feature a relatively small percent of their interfaces that use screw-machined contacts. Implementation of the lead-free mandate would have limited impact on their overall sales. Several expressed the opinion that they could switch to a higher-cost material in the short term while searching for a lower-cost alternative. The expiration of the 6(c) exemption had the potential to devastate medium and smaller connector suppliers that focus their product mix on industrial applications. These manufacturers make extensive use of commercial screw machined contacts, especially those that specialize in high-reliability and custom connectors. Demise of the exemption could turn much existing inventory into scrap.
The original exemption was set to expire on July 21, 2016. A consortium of copper material suppliers and users applied for renewal of exemption 6(c) in January of 2015, citing the inability to find a cost-effective alternative. A decision by the European Commission for extension was expected by January 21, 2016. That date passed, and the July 2016 expiration date came and went without a decision from the EU violating their own deadlines. Thankfully, existing exemptions remain in effect until the commission decides on a renewal application. Manufacturers and users of screw-machined contacts remained in limbo.
Finally, on May 18, 2018, the commission issued Directive 2018/741, which renewed exemption 6(c) through July 21, 2021; five years after the original expiration date. Parts used in select medical diagnostic devices are exempt until 2023 and those used in industrial monitoring and control instrumentation are exempt until 2024. A collective sigh of relief was heard among those that manufacture precision screw-machined parts.
Contact with several connector manufacturers indicate that they continue to anticipate future extensions but are also searching for a viable alternative material. Tellurium copper was mentioned as a possible candidate, but increased cost and limited sources are concerns.
Waiting in the background is the REACH program, another European Commission environmental regulation. This directive focuses on specific hazardous chemicals that have been used in manufacturing processes. Although it is not included in the current list of prohibited materials, certain forms of lead are considered materials of very high concern and could be added to the list of restricted REACH materials in the future.
Hope for the best (permanent exemption), plan for the worst (6(c) expiration) appears to be the current mantra. As one material engineer explained, his plan is to hope for extensions and exemptions until he retires.
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