What is RoHs that appears on electronic components?

You may have already seen the acronym “RoHs” on some electrical or electronic devices. These devices are built with different substances, and some of these substances are harmful to the environment. Taking into account the rapid technological advancement, we know that the time of use of an electronic device is increasingly shorter, which leads to accelerated disposal of electronic devices, as they are quickly replaced by new technologies. At this rate, materials hazardous to the environment, which make up these devices, are often released into nature, is highly harmful. Among these dangerous substances, we can mention lead and mercury. Knowing this, the European Union has created a way to control the use of this waste in electronic devices,

RoHS (Restriction of Certain Hazardous Substances / Restriction of Certain Hazardous Substances) is European legislation that restricts the use of certain substances in the product manufacturing process. It entered into force on July 1, 2006, as of that date, products using certain substances no longer circulated in Europe. Together with RoHs, a law on the recycling of electronic devices, WEEE (Waste from Electronic Equipment / Waste from Electronic Products) came into effect. RoHs is also called “the lead-free law”, but it is also about other substances:

  • Mercury (Hg);
  • Cadmium (Cd);
  • Lead (Pb);
  • Hexavalent chromium (Cr (VI));
  • Polybrominated biphenyls (PBBs);
  • Diphenyl-polybrominated ethers (PBDEs);

There is a tolerance of at most 0.1% of the weight of the homogeneous material, except for cadmium whose maximum allowed concentration is 0.01%.

Welding in the electronic circuit.

In addition to adapting to what restricts RoHs, manufacturers found it very difficult to follow this law. The traditional solder used to fix the devices on the board is composed of 60% tin and 40% lead. In this, manufacturers had to use other alternatives in this process. To replace the traditional way, silver, copper and bismuth are used.

Initially, RoHs only applied to the European Union, but with the process of globalization, it quickly became a norm in international markets. Other countries have also established guidelines similar to RoHS.

These materials are promising, but can pose some challenges:

  • High melting temperature:

The traditional solder (tin and lead) melts at 180º C while the lead-free solder melts at 227º C. In this new scenario, the devices to be welded must withstand this new temperature without compromising its proper functioning.

  • Still in development:

The lead-free soldering process is new and is still under development. So far there is no industry standard for lead-free soldering.

  • Repair:

To repair electronic equipment, you must use the same solder that was used in the manufacture of this equipment. This is usually specified on the card. But it is safe to use 99C alloy (99.7% tin, 0.3% copper) to repair lead-free solder equipment.

  • Visual inspection:

Lead-free soldering is different from traditional soldering, so it is not possible to accurately visualize whether a solder spot is done well or not.

In addition to soldering, all other components that make up electronic devices must not have the components prohibited by RoHS.

Products included in RoHS:

  • Large domestic equipment;
  • Small domestic equipment;
  • IT and telecommunication equipment;
  • Consumer applications;
  • Lighting equipment;
  • Electrical and electronic devices;
  • Children’s, recreational and sports equipment;
  • Automatic machines;

LED lamps, for example, do not use lead in their composition.


RoHS has exceptions regarding the use of mercury and lead. Lead can be used in:

  • Welding alloys with a melting temperature (with lead content less than 85%);
  • Piezoelectric materials;
  • Glass for cathode-ray tubes;
  • Metal alloys established in RoHs;

For mercury, the exceptions are fluorescent tubes and other types of lamps.

RoHS impacts:

From the moment RoHs came into effect, manufacturers, suppliers, and consumers were impacted. Manufacturers had to adapt to the standard, and with that, the products suffered a price increase. To replace prohibited substances, more expensive substances were used. This caused a considerable increase in products.

Labels were created to indicate the absence of lead in equipment. There are “green labels” (which indicate a decrease in the use of hazardous substances) and “lead-free” labels (meaning that the product is lead-free).

In addition to damaging the environment, lead is harmful to almost every human organism, especially the nervous system. Most electronic devices end their useful life in open dumps or in the environment, exposing the dangerous substances of their manufacture. RoHS prevent these damages and applies the recycling of these materials.