Page 1 of 253 RELIABILITY AND FAILURE ANALYSIS Review of Directive 2002/95/EC (RoHS) Categories 8 and 9 - Final Report Dr. Paul Goodman ERA Report 2006-0383 ERA Project 043121538 Final Report Client : European Commission, DG Environment Client Reference : ENV.G.4/ETU/2005/0014 ERA Report Checked by: Approved by: authorised - electronic version authorised - electronic version Dr Paul Goodman Dr Chris Robertson Senior Materials Consultant Head of Reliability and Failure Analysis Reliability and Failure Analysis July 2006 amd. 19 Sep 2006 Ref. 043121538 EC Final report f3.doc 2 ERA Report 2006-0383 - Final Report © Copyright ERA Technology Limited 2006 All Rights Reserved No part of this document may be copied or otherwise reproduced without the prior written permission of ERA Technology Limited. If received electronically, recipient is permitted to make such copies as are necessary to: view the document on a computer system; comply with a reasonable corporate computer data protection and back-up policy and produce one paper copy for personal use. Erratum The original report referred incorrectly on page 11, line 11 and page 248, line 7 to 90/385/EC (the Implanted Medical Devices Directive) whereas this should have been to 98/79/EC (the In-vitro Medical Devices Directive). This has been corrected in the present version. The document may be distributed freely in whole, without alteration, subject to Copyright. ERA Technology Ltd Cleeve Road Leatherhead Surrey KT22 7SA UK Tel : +44 (0) 1372 367444 Fax: +44 (0) 1372 367134 E-mail: [email protected] Read more about ERA Technology on our Internet page at: http://www.era.co.uk/ and about the Reliability and Failure Analysis Group at http://www.era.co.uk/rfa.htm ©Copyright ERA Technology Limited 2006 043121538 EC Final report f3.doc 3 ERA Report 2006-0383 - Final Report Executive Summary Article 6 of 2002/95/EC (RoHS) requires the European Commission to carry out a review of this Directive and present proposals for including Category 8 and 9 equipment within the scope of this Directive. This is the final report of the study carried out by ERA Technology for the European Commission to provide the technical basis for this review process. This report is based on the Interim Report (ERA Report No. 2006-0134) submitted to the European Commission in March 2006. Some sections are largely unchanged while others have been completely rewritten or are new. This final report takes into account comments and suggestions made at, and subsequent to, the “Experts Workshop” organised by the European Commission in April 2006 to obtain the views of Member States and other Stakeholders. In order to amend the RoHS Directive, it is necessary to take into account the impact this would have on healthcare, safety and the environment as well as technical issues. The Lisbon Strategy of the EU aims to protect the environment as well as EU industry and employment and so these issues are also taken into account. Manufacturers have been extensively consulted as well as many other organisations. Quantities of equipment and RoHS substances The quantities of equipment within Categories 8 and 9 sold annually in EU and the quantities of the six RoHS restricted substances have been estimated: • Category 8 equipment ~30,000 tonnes • Category 9 equipment ~30,000 tonnes The estimate for Category 8 is fairly accurate but it has proven to be very difficult to obtain reliable data for Category 9 because manufacturers are unclear of the scope of this Category. The best estimate for the actual quantity is about 30,000 tonnes and is probably no more than 60,000 tonnes. A total of 60,000 tonnes is approximately 1% of all electrical equipment sold annually in EU. Of the six RoHS substances, lead is used in Category 8 and 9 equipment in the largest quantities at an estimated 1414 tons with only 2.2 tonnes of cadmium, ~30 kg mercury, 800 kg of hexavalent chromium and <10 tonnes total for the two types of flame-retardants PBB and PBDE. Reliability of substitute materials One of the main reasons that Categories 8 and 9 were originally excluded from the scope of the RoHS Directive was concern over the reliability of substitute materials, especially lead-free solders. This was reasonable as unexpected early failure of equipment in these Categories could have serious and potentially fatal consequences. It has been prudent to wait until research has been carried out to investigate the substitute materials and develop strategies to ensure that these are not less reliable than the products manufactured using the RoHS-restricted substances. The long-term reliability of lead- ©Copyright ERA Technology Limited 2006 043121538 EC Final report f3.doc 4 ERA Report 2006-0383 - Final Report free solders has therefore been extensively investigated in this study. There are five main concerns with the use of lead-free solders: • Manufacturing defects • Thermal fatigue • Tin whiskers • Vibration and effect of g-forces • Corrosion The risk of manufacturing defects is increased by the use of lead-free solders but most of these are well understood and should be avoidable provided that sufficient time and resources are available. Research into thermal fatigue is not yet conclusive. Accelerated tests show that at low stress levels lead-free solders appear to be superior to their tin/lead equivalents, whereas they appear to be less reliable when stress levels are high. It is not yet possible, however, to predict the field life of equipment with sufficient accuracy for products that are used for >10 years and in hostile conditions on the basis of accelerated test data. This is because there is as yet no comparable field data for equipment made with lead-free solders as these are new materials. Estimation of field life from accelerated test data should be possible within the next five years but this is not yet possible with sufficient certainty for the most safety critical applications. Tin whiskers occur on electroplated tin coatings such as those used on component terminations. Extensive research is beginning to show how these are produced and whisker minimisation strategies are being developed so that the risk of whiskers is very low if these are followed. Whether Categories 8 and 9 are included in the scope of RoHS will not make a significant difference to whisker risk as manufacturers of Category 8 and 9 equipment are already being forced to buy components with tin coated terminations as alternatives are not usually available. Lead-free solders and tin-lead solders are equally reliable at low g-forces but lead-free solders have been shown to be less reliable at high g-forces in the direction perpendicular to printed circuit boards. This could affect certain types of product. Recent research has shown that printed circuit boards made using lead-free materials can be more susceptible to corrosion than their tin/lead counterparts. Unexpectedly, it has been found that corrosion occurs to gold-coated boards and components used in the most severe environments. This work is continuing but shows that sufficient time for research should always be allowed as unforeseen behaviour such as this can occur where new materials are used and not adequately understood. There has also been concern about substitutes for hexavalent chromium passivation coatings and so this has also been reviewed. These account for ~99% of all hexavalent chromium used in Category 8 and 9 products. However, research has been carried out with substitute materials and results to date ©Copyright ERA Technology Limited 2006 043121538 EC Final report f3.doc 5 ERA Report 2006-0383 - Final Report indicate that these can be used as replacements under all conditions except those found in the most severe environments such as within chemical and petrochemical process plant. The characteristics of Category 8 and 9 equipment Category 8 and 9 equipment has several important differences to equipment in the other eight WEEE Categories. In general, the majority of Category 8 and 9 products are made in small numbers, are produced for long periods without modification or changes to the design, and have to be very reliable. Although some products in the other eight Categories also have these characteristics, most are made in large numbers, models are changed more frequently and failure is inconvenient but does not pose a environmental, health or safety risk. When a manufacturer of Category 8 or 9 equipment modifies a product, they need to carry out similar activities to those manufacturers in other sectors but in addition also have to carry out extensive reliability testing, carry out validation or clinical trials and submit data to Notified Bodies for compliance with a range of Directives and industry standards. The number of trained engineers available to carry out this work is limited and so, where a manufacturer has a very large range of products, the time required to modify these to comply with RoHS can be very long. In reality, it will not be feasible to change all these products and many will be withdrawn from the EU market. It is already being shown by a small number of manufacturers that it is possible to make RoHS compliant Category 8 and 9 products but the time required is in general longer than has been required for products in the other eight Categories. For the most complex products, testing and validation can take 18 months or more and obtaining approvals under ATEX and the Medical Device Directives can take a year or more. Manufacturers would typically replace Category 8 and 9 product designs with new models after 7 – 10 years. The cost to develop a new non-RoHS compliant product would be a little lower than the cost of development of a new RoHS compliant product, at least initially, but this difference will not be large because testing and obtaining approvals will be required for all new products and so RoHS compliance normally incurs a small cost increase.