chemistry

RoHS

RoHS is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand RoHS rather than just read about it. In short: The Restriction of Hazardous Substances Directive 2002/95/EC (RoHS 1), short for Directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment, was adopted in February 2003 by the European Union. The initiative was to limit the amount of hazardous chemicals in electronics.

Key takeaways

RoHS belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect RoHS to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of RoHS from memory before moving on to harder problems.

Reference excerpt

The Restriction of Hazardous Substances Directive 2002/95/EC (RoHS 1), short for Directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment, was adopted in February 2003 by the European Union. The initiative was to limit the amount of hazardous chemicals in electronics. The RoHS 1 directive took effect on 1 July 2006, and is required to be enforced and became a law in each member state. The directive restricts (with exceptions) the use of ten hazardous materials in the manufacture of various electronic and electrical equipment. In addition to the exceptions, there are exclusions for products such as solar panels. It is closely linked with the Waste Electrical and Electronic Equipment Directive (WEEE) 2002/96/EC (now superseded) which sets collection, recycling, and reclamation goals for electrical goods and is part of a legislative initiative to solve the problem of huge amounts of toxic electronic waste. In speech, RoHS is often spelled out, or pronounced , , , or , and refers to the EU standard, unless otherwise qualified.

Details Each European Union member state will adopt its own enforcement and implementation policies using the directive as a guide. RoHS is often referred to as the "lead-free directive", but it restricts the use of the following ten substances:

Lead (Pb) Mercury (Hg) Cadmium (Cd) Hexavalent chromium (Cr6+) Polybrominated biphenyls (PBB) Polybrominated diphenyl ether (PBDE) Bis(2-ethylhexyl) phthalate (DEHP) Butyl benzyl phthalate (BBP) Dibutyl phthalate (DBP) Diisobutyl phthalate (DIBP) Maximum Permitted Concentration: 0.1% Max for Cadmium: 0.01% DEHP, BBP, DBP and DIBP were added as part of DIRECTIVE (EU) 2015/863 which was published on 31 March 2015. PBB and PBDE are flame retardants used in several plastics. Hexavalent chromium is used in chrome plating, chromate coatings and primers, and in chromic acid. The maximum permitted concentrations in non-exempt products are 0.1% or 1000 parts per million (ppm) (except for cadmium, which is limited to 0.01% or 100 ppm) by weight. The restrictions are on each homogeneous material in the product, which means that the limits do not apply to the weight of the finished product, or even to a component, but to any single material that could (theoretically) be separated mechanically – for example, the sheath on a cable or the tinning on a component lead. As an example, a radio is composed of a case, screws, washers, a circuit board, speakers, etc. The screws, washers, and case may each be made of homogenous materials, but the other components comprise multiple sub-components of many different types of material. For instance, a circuit board is composed of a bare printed circuit board (PCB), integrated circuits (IC), resistors, capacitors, switches, etc. A switch is composed of a case, a lever, a spring, contacts, pins, etc., each of which may be made of different materials. A contact might be composed of a copper strip with a surface coating. A loudspeaker is composed of a permanent magnet, copper wire, paper, etc. 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 1 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. New legislation was published in the official journal in July 2011 which supersedes this exemption. 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 increased in scope and approved in 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 programme 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 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:

… excerpt ends here. Continue reading the full article.

Illustrations

The WEEE directive logo

Worked examples

Example 1 — a first encounter with RoHS

Start with the simplest possible case. Write down what RoHS claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to RoHS before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about RoHS ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of RoHS

In research: RoHS appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses RoHS in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: RoHS is common in secondary-school and first-year university syllabi. It links to neighbouring topics 2003 in European Union law, 2003 in the environment, Electronic waste in Europe, so understanding it makes those chapters shorter.
In everyday life: Look for RoHS outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study RoHS in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what RoHS means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain RoHS out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is RoHS in simple terms?

Why does RoHS matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study RoHS?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on RoHS.