Restriction of Hazardous Substances Directive - RoHS
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The Restriction of Hazardous Substances Directive (RoHS) 2002/95/EC  was adopted in February 2003 by the European Union. The RoHS directive took effect on July 1, 2006, but is not a law; it is simply a directive. This directive restricts the use of six hazardous materials in the manufacture of various types of electronic and electrical equipment. It is closely linked with the Waste Electrical and Electronic Equipment Directive (WEEE) 2002/96/EC which sets collection, recycling and recovery targets for electrical goods and is part of a legislative initiative to solve the problem of huge amounts of toxic e-waste.
Each European Union member state will adopt its own enforcement and implementation policies using the directive as a guide. Therefore, there could be as many different versions of the directive as there are states in the EU.
RoHS is often referred to as the lead-free directive, but it restricts the use of the following six substances:
PBB and PBDE are flame retardants used in some plastics.
The maximum concentrations are 0.1% or 1000ppm (except for cadmium, which is limited to 0.01% or 100 ppm) by weight of homogeneous material. This means that the limits do not apply to the weight of the finished product, or even to a component, but to any single substance that could (theoretically) be separated mechanicallyfor example, the sheath on a cable or the tinning on a component lead.
As an example, a radio comprises a case, screws, washers, a circuit board, speakers, etc. A circuit board comprises a bare PCB, ICs, resistors, switches etc. A switch comprises a case, a lever, a spring, contacts, pins, etc. The contact might comprise a copper strip with a surface coating.
Everything that can be identified as a homogeneous material must meet the limit. So if it turns out that the case was made of plastic with 2,300 ppm (0.23%) PBB used as a flame retardant, then the entire radio would fail the requirements of the directive.
In an effort to close RoHS loopholes, in May 2006 the European Commission was asked to review two currently excluded product categories (monitoring and control equipment, and medical devices) for future inclusion in the products that must fall into RoHS compliance . In addition the commission entertains requests for deadline extensions or for exclusions by substance categories, substance location or weight .
Note that batteries are not included within the scope of RoHS. However, in Europe, batteries are under the European Commission's 1991 Battery Directive (91/157/EEC ), which was recently increased in scope and approved in the form of the new battery directive, version 2003/0282 COD , which will be official when submitted to and published in the EU's Official Journal. While the first Battery Directive addressed possible trade barrier issues brought about by disparate European member states' implementation, the new directive more explicitly highlights improving and protecting the environment from the negative effects of the waste contained in batteries. It also contains a program for more ambitious recycling of industrial, automotive, and consumer batteries, gradually increasing the rate of manufacturer-provided collection sites to 45% by 2016. It also sets limits of 5 ppm mercury and 20 ppm cadmium to batteries except those used in medical, emergency, or portable power-tool devices . Though not setting quantitative limits on quantities of lead, lead-acid, nickel, and nickel-cadmium in batteries, it cites a need to restrict these substances and provide for recycling up to 75% of batteries with these substances. There are also provisions for marking the batteries with symbols in regard to to metal content and recycling collection information.
The directive applies to equipment as defined by a section of the WEEE directive. The following numeric categories apply:
It does not apply to fixed industrial plant and tools. Compliance is the responsibility of the company that puts the product on the market, as defined in the Directive; components and sub-assemblies are not responsible for product compliance. Of course, given the fact that the regulation is applied at the homogeneous material level, data on substance concentrations needs to be transferred through the supply chain to the final producer. An IPC standard has recently been developed and published to facilitate this data exchange, IPC-1752 . It is enabled through two PDF forms that are free to use.
RoHS applies to these products in the EU whether made within the EU or imported. Certain exemptions apply, and these are updated on occasion by the EU.
Medical devices and monitoring and control instruments comprise RoHS Category 8 and Category 9 products respectively. The EU recognizes that these products are manufactured in small numbers and generally have a long product life. Further, these products are often used in mission-critical applications where their failure can reasonably be expected to be extremely disruptive, if not catastrophic. Since the long term effects of lead-free solder, a primary RoHS objective cannot be known for a period of at least five years following the directive’s application to the remaining eight categories, the EU has established at least a temporary moratorium for Category 8 and 9 products.
In an effort to gain more insight the EU commissioned a study to assess when and if the RoHS directive should be applied to Category 8 and 9 products. Released in July 2006, the Review of Directive 2002/95/EC (RoHS) Categories 8 and 9 Final Report  recommended that Category 8 and 9 products remain exempt from the RoHS directive until 2012 or 2018 depending upon specific product sub-categories and applications. Since the EU has not yet adopted this recommendation, the exact timing of RoHS application to Category 8 and 9 products remains uncertain.
There is also a regulation in China (often referred to as China RoHS) that has similar restrictions, but it in fact takes a very different approach. Unlike EU RoHS, where products are included unless specifically excluded, there will be a list of included products, known as the cataloguesee Article 18 of the regulationwhich will be a subset of the total scope of Electronic Information Products, or EIPs, to which the regulations apply. There are some products that are EIPs, which are not in scope for EU RoHSe.g. radar systems, semiconductor-manufacturing equipment, photomasks, etc. The list of EIPs is available at  in Chinese and English. The marking and disclosure aspects of the regulation took effect on March 1, 2007. There is no timeline for the catalogue yet.
Japan does not have any direct legislation dealing with the RoHS substances, but its recycling laws have spurred Japanese manufacturers to move to a lead-free process. Officially starting from July 1, 2006, Japanese manufacturers have begun phasing out lead and other harmful materials in accordance with RoHS guidelines. Japan does have a marking requirement called J-MOSS, effective July 1, 2006, on some electronic products.
South Korea promulgated the Act for Resource Recycling of Electrical and Electronic Equipment and Vehicles on April 2, 2007. This regulation has aspects of RoHS, WEEE, and ELV. More information is available at .
California has passed SB 20: Electronic Waste Recycling Act of 2003, or EWRA. This law prohibits the sale of electronic devices after January 1, 2007, that are prohibited from being sold under the EU RoHS directive, but across a much narrower scope that includes LCDs, CRTs, and the like and only covers the four heavy metals restricted by RoHS. EWRA also has a restricted material disclosure requirement.
Other US states and cities are debating whether to adopt similar laws, and there are several states that have mercury and PBDE bans already. Federal RoHS-like regulation in the US is unlikely in the near to medium term.
RoHS is not the only environmental standard of which electronic product developers should be aware. Manufacturers will find that it is cheaper to have only a single bill of materials for a product that is distributed worldwide, instead of customizing the product to fit each country's specific environmental laws. Therefore, they develop their own standards, which allow only the least common denominator of all allowable substances.
For example, IBM forces each of their suppliers to complete a Product Content Declaration form to document compliance to their environmental standard Baseline Environmental Requirements for Materials, Parts and Products for IBM Logo Hardware Products. So for example, IBM bans DecaBDE, even though there is a RoHS exception for this material.
Negative impacts on product quality and reliability, plus high cost of compliance (especially to small business) are cited as criticisms of the directive, as well as a growing body of research indicating that the life cycle impact of lead free solder is more significant than that of traditional solder materials.
Restricting lead content in solders for electronics requires expensive retooling of assembly lines and different coatings for the leads of the electronic parts. Low-lead solders have a higher melting point (up to 260 °C, instead of just 180 °C), requiring different materials for chip packaging and for some circuit boards; the overheating also precludes the use of components that cannot survive the higher temperature. Low-lead solders are also harder, resulting in slow development of cracks (instead of plastic deformation, as the softer Sn-Pb solder does) because of thermal expansion and contraction as some parts heat up and cool down during operation, thus significantly impairing long-term reliability and device lifetime.
The editor of Conformity Magazine  wonders if the transition to lead-free solder will not impact long-term reliability of electronic devices and systems, especially in applications more mission-critical than in consumer products, citing possible breaches due to other environmental factors like oxidation . This article refers to the Newark In One "RoHS Legislation and Technical Manual" , which cites these and other "lead-free" solder issues, such as:
(1) warpage or delamination of printed circuit boards, (2) damage to through-holes, ICs and components on circuit boards, and (3) added moisture sensitivity, all of which may compromise quality and reliability.
Admission of reliability problems is found in Annex, item #7, of the RoHS directive itself, granting servers exemption from regulation until 2010. 
Another problem that lead-free solders face is the growth of tin whiskers. These thin strands of tin can grow and make contact with an adjacent trace, developing a short circuit. Tin whiskers have already been responsible for at least one failure at a nuclear power plant.  Other documented failures include satellites in orbit, aircraft in flight, and implanted medical pacemakers.
Reliability decay of low-lead materials may be economically desirable for some consumer product companies because it provides a mechanism to enforce planned obsolescence and replacement. Ironically, this is the opposite of the claimed intent of RoHS legislation.
Some countries have exempted medical and telecommunication infrastructure products from the legislation.  There are no de minimus exemptions e.g. for micro-businesses, meaning that some small businesses have closed down, citing the cost of compliance.
The US EPA has published a life cycle analysis which compares lead-free and lead solder in terms of environmental impact. While the lead-free alternatives are shown to have an approximately two orders of magnitude improvement over leaded solders with regards to occupational health impacts (non-cancerous), certain aspects of lead-free solders are slightly worse, environmentally, than leaded solders.
Another life-cycle assessment  by IKP, University of Stuttgart, shows similar results to those of the EPA study. A specific environmental concern has been raised at the beginning of lifecycle analysis, where gold or silver is used to replace the lead. It is difficult to valuate without knowing which mine the gold or silver is extracted from. Gold and silver mining release more mercury into the environment than lead mining, and an increasing percentage of this mining occurs in acutely sensitive areas .
In an article published in Advanced Packaging, November/December 2006, Glenn A. Rinne of Unitive Electronics, Inc. (an Amkor Company) describes the allotropic phase transformation of tin, also known as tin pest, which begins at temperatures below 13C (about 55F). Tin pest causes solder joints affected by it to crumble. The effect is difficult to predict and control, because the transformation is slow. Interestingly, the effect was already known more than 100 years ago, as it has been at various times been cited as a factor in the failure of Napoleon's Russian campaign, and Robert Scott's South Pole expedition.