RoHS Compliance in PCBs: What Designers Need to Know

RoHS-compliant in the context of PCBs (Printed Circuit Boards) means that the board and its components adhere to the Restriction of Hazardous Substances (RoHS) directive. RoHS is a set of regulations that restrict the use of certain hazardous materials commonly found in electronic and electrical equipment. The primary goal is to reduce environmental impact and improve health safety during manufacturing, usage, and disposal. To know how PCBs are made in JLPCB fab, visit our comprehensive guide on PCB manufacturing.

Originating in the EU, the directive restricts the use of hazardous materials like lead, cadmium, and mercury in electrical and electronic equipment. For PCB designers, adhering to RoHS standards is not just a legal requirement in many markets but also an ethical commitment to sustainability. If you sell to the EU, you must ensure that your PCB complies with the latest RoHS (restriction of hazardous substances) directive, which limits these substances in electrical and electronic equipment.

• The directive’s goal is to reduce these hazardous substances' environmental impact and health risks.
• RoHS-compliant PCB assembly is crucial for electronics sold in the EU market

If you are developing a product for the EU market, it is your responsibility to ensure that you are compliant with the latest RoHS (restriction of hazardous substances) directive (RoHS 2,3), which limits the presence of these substances in electrical and electronic equipment. These requirements extend to PCB designers and manufacturers, who must be able to demonstrate RoHS-compliant PCB assembly.

Why RoHS Compliance Matters

• Global Market Access: Many regions, including the EU, China, and California, mandate RoHS compliance for electronic products.

• Environmental Sustainability: By reducing hazardous waste, RoHS contributes to a safer environment and supports recycling efforts.

• Consumer Safety: Products adhering to RoHS are less likely to pose health risks.

Key Aspects of RoHS Compliance for PCBs

1. Restricted Substances:
RoHS limits ten hazardous materials, including lead, hexavalent chromium, and specific flame retardants. For PCBs, this means using lead-free solder, compliant surface finishes, and environmentally safe laminates.

2. Material Selection:
Designers must carefully choose components and board materials that meet RoHS guidelines. Common alternatives include:

• Lead-free solder alloys like SAC305 (tin-silver-copper).
• Surface finishes like ENIG (Electroless Nickel Immersion Gold) or OSP (Organic Solderability Preservative).

To accommodate lead-free solder, PCB fabrication and assembly processes must be adjusted. You might need to adjust reflow profiles, refine PCB surface finishes, and fine-tune assembly.

3. Heat Management:
Lead-free solder typically requires higher reflow temperatures, demanding PCBs with better thermal resilience. Designers should evaluate the board's TG (glass transition temperature) and decomposition temperature.

4. Availability of Components:

Designers must ensure all components used in PCB assembly are RoHS compliant. Traditionally, lead-based components were commonly used, so alternative parts that meet RoHS requirements might have to be sourced.

5. Reliability and Testing:

As lead-free solder can be brittle, it can impact the reliability of PCB assemblies. To make sure the final product is reliable, designers need to take this into account.

6. Supplier Collaboration:

All parties must work together to ensure they understand the RoHS requirements and can provide the necessary documentation.

Generally, RoHS compliance affects everything from material selection to component availability to manufacturing processes. PCB designers can meet regulatory requirements, reduce environmental impact, and enhance the reliability and performance of final boards by proactively addressing these factors during design.

Restricted Substances Under ROHS compliance:

The directive’s goal is to reduce these substances' environmental impact and health risks.  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)

The maximum permitted concentrations in non-exempt products are 0.1% or 1000 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.

Before products can be sold in the EU, PCB manufacturers, importers, and distributors must comply with RoHS regulations. A PCB assembly can't contain these restricted substances above the allowable limit to be ROHS compliant. In addition, they have to retain proper documentation and traceability to demonstrate compliance.

ROHS 1/2/3 Revisions:

RoHS 1 (Directive 2002/95/EC):

RoHS 1 was first published in the EU and took effect on July 1st 2006; it is required to be enforced and become a law in each EU member state. RoHS1 restricts the use of SIX hazardous materials:

Cadmium (Cd)

Lead (Pb), Mercury (Hg)

Hexavalent Chromium (Cr VI)

Polybrominated Biphenyls (PBB)

Polybrominated Diphenyl Ethers (PBDE).

RoHS 2 (The following materials with max permitted concentrations are added):

Cadmium (Cd): <100 ppm

Lead (Pb): <1000 ppm

Mercury (Hg): <1000 ppm

Hexavalent Chromium: (Cr VI) <1000 ppm

Polybrominated Biphenyls (PBB): <1000 ppm

Polybrominated Diphenyl Ethers (PBDE): <1000 ppm

RoHS 3 (Addition of phthalates):

Bis(2-Ethylhexyl) phthalate (DEHP): <1000 ppm

Benzyl butyl phthalate (BBP): <1000 ppm

Dibutyl phthalate (DBP): <1000 ppm

Diisobutyl phthalate (DIBP): <1000 ppm

Testing for RoHS Compliance

In addition to self-governing and reporting, Portable RoHS analyzers also known as X-ray fluorescence or XRF metal analyzers, are used for screening and verification of the restricted metals. With the implementation of RoHS 3 and the four added phthalates, different testing is needed to ascertain levels of these compounds, which are extracted with a solvent.

Identification and importance of RoHs Boards

Being a RoHS-compliant PCB manufacturer involves accurately identifying PCBs and materials that meet these standards. Manufacturers should provide extensive documentation, including a RoHS Certification of Conformance and clear labeling, to assure customers of compliance.

RoHS-compliant PCBs are crucial for environmental and worker safety, as they avoid hazardous chemicals that could harm landfill ecosystems or pose risks during fabrication. Proper adherence ensures the PCB materials align with health and safety regulations, safeguarding both the environment and the people involved in production.

For RoHS-compliant circuit boards, this will include the RoHS Certification of Conformance with each shipment, and the packaging on all appropriate items will provide a RoHS/Pb-Free designations.

RoHS Requirements for PCB Manufacturing

Printed circuit board manufacturing and assembly is squarely within the scope of RoHS 2, since PCBs are core components of nearly all electronic equipment. This has major implications for PCB material sourcing, fabrication, assembly, and testing processes in order to comply. Here are key requirements for PCB manufacturing under RoHS:

• Materials: Substrates like FR-4 must avoid restricted brominated flame retardants, while alternatives like ceramic substrates must be free of phthalates.
• Solder: Use lead-free alloys (e.g., tin-silver-copper); flux must also comply.
• Plating: Avoid hexavalent chromium and cadmium; opt for finishes like ENIG or OSP.
• Components: Ensure lead-free terminations and compliance with restricted substance limits.
• Documentation: RoHS labels, markings should be present both on bare boards as well as assembled PCBs.

Adhering to these guidelines ensures PCB manufacturing avoids any use of restricted hazardous substances per RoHS 2 standards.

Challenges for PCB Designers

• Cost Implications: Lead-free materials and processes can be more expensive.
• Compatibility Issues: Older components may not meet RoHS standards, requiring redesigns.
• Durability Concerns: Lead-free solder joints may be more prone to mechanical stress.

see how JLCPCB archive Impedance matching in PCBs, here is our detailed article on PCB impedance matching.

Conclusion

RoHS stands as one of the most influential environmental regulations shaping the electronics industry over the past two decades. Its restrictions on hazardous substances fundamentally changed materials, components and processes for PCB manufacturing.

Here at JLCPCB our most common and popular Printed Circuit Boards utilize Hot Air Solder Leveling (HASL) Lead Free solder plating; manufacturing processes/component and sub-component supply chains, assembly processes, and packaging processes are regularly audited and inspected for RoHS compliancy. As the industry embraces sustainability, RoHS principles will remain pivotal in ensuring responsible material usage, promoting human health, and protecting the environment.