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The Restriction of Hazardous Substances (RoHS) Directive is a set of regulations that aims to limit the use of certain harmful substances in electrical and electronic equipment. The directive was adopted by the European Union in 2003 and has been updated several times since then. The RoHS directive covers six substances: lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs). These substances are known to have negative impacts on human health and the environment, such as causing cancer, neurological damage, reproductive problems and pollution.
One of the main applications of the RoHS directive is in the printed circuit board (PCB) industry. PCBs are essential components of many electronic devices, such as computers, smartphones, TVs, radios and medical equipment. PCBs consist of layers of conductive material, such as copper, that are etched with traces and pads to connect various electronic components. The components are then soldered onto the PCB using a molten metal alloy, usually containing lead.
However, lead is one of the substances that is restricted by the RoHS directive. Therefore, PCB manufacturers have to find alternative ways to assemble their products without using lead-based solder. This is known as RoHS-compliant printed circuit assembly (PCA). RoHS-compliant PCA involves using different types of solder alloys, such as tin-silver-copper (SAC), tin-copper (SnCu) or tin-bismuth (SnBi). These alloys have different melting points, mechanical properties and reliability than lead-based solder. Therefore, PCB manufacturers have to adjust their processes and equipment to accommodate these changes.
RoHS stands for Restriction of Hazardous Substances, a directive that originated in the European Union and limits the use of six specific materials in electrical and electronic equipment. These materials are:
- Lead
- Mercury
- Cadmium
- Hexavalent chromium
- Polybrominated biphenyls
- Polybrominated diphenylether
The aim of RoHS is to reduce the environmental impact and health risks of these hazardous substances, especially when the products end up in landfills or recycling processes . RoHS also protects the workers who fabricate and handle the circuit boards.
If you sell or export your products to the EU, you must ensure that your circuit boards comply with the latest RoHS directive, which is RoHS 3 as of 2019. Non-compliance can result in fines, penalties, or product recalls. RoHS compliance also demonstrates your commitment to social responsibility and environmental sustainability.
In addition, some other regions and countries have adopted similar regulations to RoHS, such as China, Japan, California, etc. Therefore, designing RoHS compliant circuit boards can help you meet the global standards and expand your market potential.
RoHS-compliant PCA is not only a legal requirement but also a competitive advantage for PCB manufacturers. By adopting RoHS-compliant PCA, PCB manufacturers can demonstrate their commitment to social responsibility and environmental sustainability, as well as meet the expectations and demands of their customers and stakeholders. RoHS-compliant PCA can also open up new markets and opportunities for PCB manufacturers, as more countries and regions adopt similar regulations to limit the use of hazardous substances in electronic equipment.
- Higher soldering temperatures: Most lead-free solder alloys have higher melting points than lead-based solder, which means that more heat is required to melt and join them. This can affect the thermal stress on the PCB and the components, as well as increase the energy consumption and cost of the soldering process. However, higher soldering temperatures can also improve the wetting and spreading of the solder, resulting in stronger joints and better electrical conductivity.
- Different surface finishes: The surface finish of a PCB is a thin layer of material that is applied to the copper traces and pads to prevent oxidation and corrosion. The surface finish also affects the solderability and reliability of the PCA. Some common surface finishes for lead-based PCA are hot air solder leveling (HASL), organic solderability preservative (OSP) and electroless nickel immersion gold (ENIG). However, these finishes may not be compatible with lead-free solder alloys, which can cause problems such as poor wetting, intermetallic formation, whisker growth and tin pest. Therefore, PCB manufacturers have to choose different surface finishes for RoHS-compliant PCA, such as immersion silver (ImAg), immersion tin (ImSn) or electroless nickel electroless palladium immersion gold (ENEPIG).
- Improved environmental performance: One of the main benefits of RoHS-compliant PCA is that it reduces the amount of hazardous substances that are used and released in the PCB industry. This can help protect the health and safety of workers, consumers and communities, as well as reduce the environmental impact of electronic waste. According to a study by the European Commission, the RoHS directive has prevented about 100,000 tonnes of hazardous substances from entering the EU market every year since 2006.
To design RoHS compliant circuit boards, you need to consider the following aspects:
- Material selection: You need to choose the substrate materials that do not contain the restricted substances or have them below the maximum concentration value (MCV). Some examples of RoHS compliant substrate materials are Isola, Polyclad Rogers, Getek and Nelco products.
- Surface finish selection: You need to choose the surface finishes that do not contain lead or other restricted substances. Some examples of RoHS compliant surface finishes are ENIG (electroless nickel immersion gold), immersion silver, immersion tin, lead-free HASL (hot air solder leveling), and OSP (organic solderability preservative) .
- Solder selection: You need to choose the solder alloys that do not contain lead or other restricted substances. Some examples of RoHS compliant solder alloys are SAC (tin-silver-copper), SnCu (tin-copper), SnAg (tin-silver), and SnBi (tin-bismuth).
- Identification and documentation: You need to properly identify and label your circuit boards as RoHS compliant, and provide the necessary documentation and certification to prove your compliance. For example, you can use a green "e" logo or a "Pb-free" logo on your PCBs, and provide a RoHS Certificate of Conformance with each shipment.
Conclusion
Designing RoHS compliant circuit boards is not only a legal requirement for selling to the EU market, but also a good practice for reducing environmental pollution and health hazards. By following the guidelines above, you can ensure that your circuit boards meet the RoHS standards and avoid any potential risks or penalties. You can also work with a reliable PCB manufacturer that has experience and expertise in producing RoHS compliant PCBs, such as PCB International.
