The Race for ROHS Compliance

The EU directive 2002/95/EC on the restriction of the use of certain hazardous substances – otherwise known as RoHS – came into force on 1 July 2006. It restricts the use of six substances in a wide variety of electrical equipment, as defined by the related waste electronic and electrical equipment (WEEE) directive’s ten categories.

However, RoHS excludes medical devices (category 8) and monitoring and control instruments (category 9), due to concerns over the reliability of substitute materials, particularly of lead in solders, in safety-critical equipment. The directive states, however, that the European Commission will present proposals for including these categories at some point in the future.

To determine whether it will be possible to include categories 8 and 9 in the scope of RoHS, the Commission awarded a contract to ERA Technology to carry out a thorough review of the directive and the status of these two categories in particular. This review is now complete, and has been published by the European Commission on its website. The next task is to carry out an impact assessment and submit proposals for amending the directive to the European Parliament and Council of Ministers.

ERA REVIEW

ERA consulted with medical device trade associations, large, medium and small manufacturers, the European Commission department responsible for medical devices, a hospital and several technical experts to gain an understanding of the issues involved and to provide the information required by the Commission. As the main reason for the exclusion of categories 8 and 9 was uncertainty over reliability, this has been one of the main areas for investigation.

The medical device industry is unlike other sectors of the electronics industry and differences need to be taken into account. Failure of consumer products is inconvenient, but unexpected failures of medical equipment can lead to the death or injury of patients. Therefore, to develop new RoHS-compliant products, more time is needed for research, reliability testing, trials and gaining approvals from notified bodies in the EU and their equivalents in other parts of the world.

It is clear that manufacturers of the most complex medical equipment will require more time to achieve compliance than was needed by manufacturers in other sectors. Manufacturers of the more complex IT and telecom products (now within the scope of RoHS) found that the time to reach full compliance was three years or longer. The time required for medical equipment manufacturers will be longer, as in addition to the time required for design and process development, more extensive product testing is required and the time needed for approvals can be six months or longer.

Some medical equipment manufacturers have told ERA that they will be able to complete work to change their product range by 2008, but most have provided dates of 2009, 2010 or later. ERA has recommended a date of 2012 to allow sufficient time for manufacturers of the most complex equipment to comply. In vitro diagnostics equipment is a special case, for which ERA has recommended a later date of 2016.

This date is being recommended because these are complex products that require extensive validation after modifications in addition to reliability testing and submission for approvals. The timescales are extended because of a lack of qualified engineers able to carry out this work. Owing to the very high safety risk from implanted medical devices, ERA is recommending that these are excluded until 2020 or permanently.

Inclusion of category 8 in the scope of RoHS will be possible in the future, but only with many additional specific exemptions. These are permitted by the RoHS directive, where no substitutes exist. ERA is recommending 20 new exemptions for categories 8 and 9, although this number includes several different types of sensor, detector and electrode combined into one broad exemption.

CURRENT SITUATION

The RoHS directive is already affecting medical equipment manufacturers in a variety of ways. A small number did not realise that category 8 was excluded from RoHS and so already have RoHS-compliant products. Many have decided that, as the eventual inclusion of category 8 in the scope of RoHS appears inevitable, they will develop all-new designs to be RoHS-compliant, although they have no plans to change current models. Several of the manufacturers consulted by ERA were unwilling to produce and sell new products using lead-free solders, as they believe that these will continue to pose a small risk to safety until their long-term reliability in the field is proven. This is expected to take several years.

Extensive research with lead-free solders has been carried out since the 1990s, and these alloys are now fairly well understood. However, the piece of information that is still missing is how they behave under field conditions over a ten to 15 year period. Accelerated test results are encouraging, but prediction of field-life from this data cannot yet be estimated with sufficient accuracy.

Most medical equipment is produced in small volumes and producers have little influence over component manufacturers. As most components are used in mass-produced consumer-type products which already comply with RoHS, these have either been changed to RoHS-compliant versions or, in some cases, they have become obsolete as sales have dropped to uneconomic levels.

Replacing obsolete components can involve a great deal of work, which may not be worthwhile if future profits cannot meet these costs. Often, alternative ICs require different circuit designs and newer processor chips will require new software, both of which can take many months of work. After any significant changes are made, products will need to be tested to validate their function and evaluate reliability, and the new design and test results submitted to a notified body for approval under the relevant medical device directive.

All but the largest medical equipment manufacturers use subcontractors to manufacture their printed circuit boards. Subcontractors seldom serve only medical equipment manufacturers and will often have other customers whose products must be RoHS-compliant. Some PCB subcontractors are installing separate production lines for lead-based and lead-free processes, but in the longer term the majority will inevitably produce only lead-free products, forcing all of their customers towards lead-free production.

FUTURE LEGISLATORY REQUIREMENTS

It is likely that medical equipment will be included in the scope of RoHS in the future. Similar legislation is being introduced in the rest of the world, notably in China and California. Many manufacturers have realised that modifying their full product ranges to comply with RoHS will require considerable effort and resources and will take many years, so they have already started work.

Manufacturers who produce a variety of products will need the most time, as each model that is significantly changed will have to be tested and submitted for approvals. The time required for complex equipment such as PET and CT scanners will inevitably be several years, with difficult technical challenges to overcome.

One important question, however, is whether the new RoHS-compliant products will be safe to use and be reliable. The ERA review has investigated this topic in detail, looking at all of the main potential failure mechanisms. Tin/lead solders can be unreliable, as failures do occasionally occur, but, after many decades in use, the performance of these alloys is well understood.

The performance of lead-free solders is uncertain, however, because they are relatively new and it is unclear whether they will be more or less reliable than tin/lead. Research indicates they could be. Under some circumstances they might be more reliable, although under others they will be less reliable. These predictions are based on accelerated testing and so there will be uncertainty over their validity, which can be confirmed only when field data is available.

Extensive research carried out over the last ten years or so has shown how to use lead-free solders, how to avoid production defects and why tin whiskers form and how to avoid them. As a result, we are beginning to identify the field conditions that can shorten the life of electrical equipment.

CONCERNS OVER INNOVATION

All manufacturers endeavour to produce innovative products to increase sales and, in the case of categories 8 and 9, to provide real benefits to their customers. Innovations to medical devices allow earlier and more accurate diagnosis and also safer and more effective treatment. Medical equipment manufacturers are concerned that any restrictions on their research will result in potentially life-saving inventions not being developed.

Researchers do not deliberately use toxic substances, but the recent development of cadmium-based X-ray detectors has shown that, sometimes, physics dictates that only certain materials will be suitable. Restricting the RoHS substances is a concern, as the procedure for requesting and gaining an exemption is far too long for most research projects, which tend to be carried out at universities over one- or two-year periods.

It can take well over a year to obtain an exemption and this timescale seems to be getting longer, with no guarantee that a request will be accepted. This approach is clearly unacceptable, but the European Commission is unable to offer an alternative mechanism with the RoHS directive in its present form.

INCREASING RESTRICTIONS

Restrictions on the use of hazardous substances are constantly increasing, with RoHS being one of many pieces of legislation that will affect medical equipment manufacturers in the future. It is likely that medical equipment will be brought within the scope of RoHS in the future – not before 2010 but possibly by 2012.

Many manufacturers are already aware of this and are working towards compliance by developing new RoHS-compliant products, although most are not modifying their existing models. The medical sector is different in many ways to other sectors, so inclusion of category 8 in the scope of RoHS will have additional impacts on their businesses and could, if the date of inclusion is too early, also affect healthcare through loss of product diversity and possible price increases.

In the longer term, RoHS-type legislation will be adopted worldwide (such as in China, where RoHS marking is now required on all medical devices manufactured from 1 March 2007 and sold in China), and so it will be prudent to avoid the use of hazardous substances wherever possible, even if they are not restricted yet. However, the limitations on innovation are a real concern with no obvious way of resolving this issue.