What are RoHS Compliant Circuit Boards?

RoHS stands for Restriction of Hazardous Substances. It is a directive that restricts the use of certain hazardous substances in electrical and electronic equipment. The directive was first adopted by the European Union in 2003 and has since been revised several times. The current version, RoHS 3, came into effect on July 22, 2019.

RoHS compliant circuit boards are those that meet the requirements set forth in the RoHS directive. This means that they do not contain any of the restricted substances above the maximum concentration values allowed.

The restricted substances and their maximum concentration values are:

Substance	Maximum Concentration Value
Lead (Pb)	0.1%
Mercury (Hg)	0.1%
Cadmium (Cd)	0.01%
Hexavalent Chromium (Cr6+)	0.1%
Polybrominated Biphenyls (PBB)	0.1%
Polybrominated Diphenyl Ethers (PBDE)	0.1%
Bis(2-Ethylhexyl) phthalate (DEHP)	0.1%
Benzyl butyl phthalate (BBP)	0.1%
Dibutyl phthalate (DBP)	0.1%
Diisobutyl phthalate (DIBP)	0.1%

These substances are restricted because they are known to be harmful to human health and the environment. Lead, for example, can cause damage to the nervous system and kidneys, while cadmium is a known carcinogen.

Why are RoHS Compliant Circuit Boards Important?

RoHS compliant circuit boards are important for several reasons:

1. Environmental Protection

The primary goal of the RoHS directive is to protect the environment by reducing the amount of hazardous waste generated by electrical and electronic equipment. By restricting the use of certain substances, the directive aims to reduce the environmental impact of these products throughout their lifecycle, from production to disposal.

2. Human Health

The restricted substances are known to be harmful to human health, particularly to children and pregnant women. By reducing exposure to these substances, RoHS compliant circuit boards help to protect the health of workers involved in their production, as well as the health of consumers who use products containing these boards.

3. Legal Compliance

For companies that sell products in the European Union, RoHS compliance is a legal requirement. Non-compliant products cannot be sold in the EU market, and companies that violate the directive can face significant fines and other penalties.

4. Market Access

Even for companies that do not sell products in the EU, RoHS compliance can be important for accessing other markets. Many countries around the world have adopted similar regulations, and some companies may require their suppliers to provide RoHS compliant components.

How are RoHS Compliant Circuit Boards Manufactured?

The manufacturing process for RoHS compliant circuit boards is similar to that of non-compliant boards, with a few key differences:

1. Material Selection

The first step in manufacturing RoHS compliant circuit boards is to select materials that do not contain any of the restricted substances. This includes the base material (typically FR-4), copper foil, solder mask, and silkscreen.

2. Lead-Free Soldering

One of the most significant changes required for RoHS compliance is the use of lead-free solder. Traditional tin-lead solder contains around 40% lead, which is well above the maximum concentration value allowed under RoHS.

Lead-free solder typically contains a combination of tin, silver, and copper (SAC). The most common alloy is SAC305, which contains 96.5% tin, 3% silver, and 0.5% copper. Other alloys, such as SAC387 and SAC405, are also used.

Lead-free soldering requires higher temperatures and longer dwell times compared to traditional tin-lead soldering. This can lead to increased thermal stress on components and may require changes to the design of the circuit board to accommodate these higher temperatures.

3. Cleaning and Finishing

After soldering, the circuit boards are cleaned to remove any flux residue or other contaminants. This is typically done using a cleaning agent that is compatible with the solder mask and other materials used on the board.

The boards are then finished with a surface treatment, such as ENIG (electroless nickel immersion gold) or OSP (organic solderability preservative). These treatments help to protect the exposed copper and improve the solderability of the board.

4. Testing and Inspection

RoHS compliant circuit boards are subject to additional testing and inspection to ensure that they meet the requirements of the directive. This may include X-ray fluorescence (XRF) testing to verify the composition of the materials used, as well as visual inspection to check for defects or other issues.

Challenges of RoHS Compliant Circuit Boards

While RoHS compliance is important for protecting the environment and human health, it does present some challenges for manufacturers and designers of circuit boards:

1. Higher Costs

The materials and processes used to manufacture RoHS compliant circuit boards are generally more expensive than those used for non-compliant boards. This is particularly true for lead-free solder, which can be 2-3 times more expensive than traditional tin-lead solder.

2. Reliability Concerns

The higher temperatures and longer dwell times required for lead-free soldering can lead to increased thermal stress on components, which may reduce their reliability over time. This is particularly true for smaller components with fine pitch leads, such as BGAs and QFNs.

3. Design Challenges

The higher temperatures and longer dwell times required for lead-free soldering may also require changes to the design of the circuit board. This may include increasing the size of the solder pads, adjusting the placement of components, or using different materials for the base and solder mask.

FAQ

1. What is the difference between RoHS and REACH?

RoHS and REACH are both European Union regulations that restrict the use of certain hazardous substances, but they have some key differences:

• RoHS specifically applies to electrical and electronic equipment, while REACH applies to all chemicals and products containing chemicals.
• RoHS restricts the use of 10 specific substances, while REACH requires companies to register and provide safety information for all chemicals they produce or import in quantities of one ton or more per year.
• RoHS sets maximum concentration values for the restricted substances, while REACH requires companies to identify and manage the risks associated with the substances they use.

2. Are all electronic products required to be RoHS compliant?

No, not all electronic products are required to be RoHS compliant. The RoHS directive applies specifically to electrical and electronic equipment that falls within certain categories, such as large and small household appliances, IT and telecommunications equipment, lighting equipment, and toys and leisure equipment.

Some products, such as medical devices and monitoring and control instruments, are exempt from the RoHS directive or have extended compliance deadlines.

3. How can I tell if a circuit board is RoHS compliant?

There are a few ways to tell if a circuit board is RoHS compliant:

• Look for the RoHS symbol on the board or packaging. This symbol consists of a crossed-out wheeled bin and indicates that the product meets the requirements of the RoHS directive.
• Check the manufacturer’s documentation or website for information on RoHS compliance. Many manufacturers will provide a RoHS compliance statement or certificate for their products.
• Use an XRF analyzer to test the composition of the materials used in the board. This can provide a more definitive answer, but requires specialized equipment and training.

4. Can RoHS compliant circuit boards be reworked or repaired?

Yes, RoHS compliant circuit boards can be reworked or repaired, but it is important to use RoHS compliant materials and processes when doing so. This includes using lead-free solder and flux, as well as cleaning agents and other materials that do not contain any of the restricted substances.

It is also important to take care when reworking or repairing RoHS compliant boards, as the higher temperatures and longer dwell times required for lead-free soldering can lead to increased thermal stress on components.

5. What are the penalties for non-compliance with the RoHS directive?

The penalties for non-compliance with the RoHS directive vary depending on the country and the specific violation, but can be significant. In the European Union, companies that violate the directive can face fines of up to €500,000 or 2% of their annual turnover, whichever is greater.

In addition to fines, non-compliant products may be banned from sale in the EU market, and companies may face legal action from consumers or other stakeholders who are harmed by the non-compliant products.

Conclusion

RoHS compliant circuit boards are an important part of the global effort to reduce the environmental and health impacts of electronic products. By restricting the use of certain hazardous substances, the RoHS directive helps to protect workers, consumers, and the environment from the harmful effects of these substances.

While RoHS compliance presents some challenges for manufacturers and designers of circuit boards, the benefits of compliance far outweigh the costs. By investing in RoHS compliant materials and processes, companies can not only meet their legal obligations, but also demonstrate their commitment to sustainability and social responsibility.

As the world becomes increasingly focused on environmental protection and sustainable development, the importance of RoHS compliance will only continue to grow. By staying up-to-date with the latest developments in RoHS and other environmental regulations, manufacturers and designers of circuit boards can position themselves for success in a rapidly changing market.