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How RoHS Compliant PCB Assembly is Contributing to Environmental Protection

The use of hazardous materials in printed circuit boards and electronic devices is a cause for concern. These materials pose environmental threats and risks to human health. Their negative environmental impact is a growing concern in the electrical and electronics industry. To combat this problem, the government has sought for the best ways to stop the use of these materials in electronic and electrical product.

Regulations that restrict the use of these materials are being imposed on PCB companies and electronics companies. It is crucial to design and manufacture safer electronic boards since these boards are used in several applications including the medical field. The RoHS is one of such regulations designed to restrict the use of hazardous substances and materials in electronic boards.

What is RoHS Compliant?

Mister FPGA PCB Board
Mister FPGA PCB Board

The European Union Parliament passed a law that influenced the electronic industry. The first legislation which was the Waste Electrical & Electronic Equipment (WEEE) addressed the need for manufacturers to dispose their finished goods while the second legislation was the Restriction of Hazardous Substances (RoHS).

This regulation states that it is illegal for electronic or electrical products to include restricted materials. These materials that are restricted are harmful to our environment as well as the human health. On July 1, 2006, this legislation took its effect. Also, RoHS focuses on the smallest component or material that can be removed from an assembly.

According to the RoHS directive, any electronic or electrical product must not include substances such as mercury, polybrominated biphenyls (PBB), mercury, hexavalent chromium, Octa PBDE, Cadmium, and lead. This directive must be applied in all electronic or electrical products manufactured and sold in the European Union countries.

Therefore, any Original Equipment Manufacturer (OEM) that manufactures and supplies electronic products like PCBs must comply with this directive. The RoHS compliance specifies the highest levels of these restricted materials in circuit boards and electronic products. For example Mercury must be less than 100 ppm, Cadmium must be less than 100 ppm and lead must be less than 1000 ppm.

RoHS compliance refers to the adherence to the RoHS regulations. A PCB manufacturer or electronic manufacturer is RoHS compliant when they ensure there are products are completely free of the above named materials.

The RoHS directive states that:

  • Mercury (Hg) < 100 ppm
  • Dibutyl phthalate < 1000 ppm
  • Lead (Pb): < 1000 ppm
  • Diisobutyl phthalate  < 1000 ppm
  • Polybrominated Diphenyl Ethers < 1000 ppm
  • Cadmium (Cd): < 100 ppm
  • Hexavalent Chromium < 1000 ppm
  • Bis(2-Ethylhexyl) phthalate < 1000 ppm

What is a RoHS Compliant PCB Assembly?


The RoHS directive is also applicable in the manufacturing of printed circuit boards. This is because printed circuit boards are usually integrated in the production of electronic devices. Also, these boards are the building blocks of most electrical or electronic equipment.

A RoHS compliant PCB assembly is a fully assembled board that features none of the substances mentioned above. This PCBA has no lead, mercury or any harmful substance. It is completely free of these hazardous substances. Hence, such a board is referred to as a RoHS compliant PCB assembly.

RoHS compliant PCB assembly is also known as a lead-free PCB. Tin-lead solder was commonly used in circuit boards before the RoHS directive was implemented. This type of solder was used because it offered perfect bonding. Also, it was applied as a surface finish to prevent the copper on the PCB from any corrosion.

However, the implementation of the RoHS directives made PCB assemblers to use another material and component approved by RoHS for their PCBs. The electronic industry now integrates lead free solder alloys. These materials comply with the RoHS directive. Also, the implementation of the RoHS directive made PCB manufacturer integrate lead-free PCB surface finishes and components.

These days, most manufacturers are producing RoHS compliant PCB assembly, although some customers still request for tin-lead PCB assembly. In general, the implementation of the RoHs directives has helped to minimize ground water’s contamination. When PCBs that comprises harmful substances are disposed, the substances in these boards end up contaminating the environment.

Benefits of RoHS Compliant PCB Assembly

RoHS compliant PCB assembly offers a lot of benefits. Since the implementation of the RoHS directives, the environmental impact has been positive. Ground water is no longer contaminated with harmful substances. Also, electronic consumers feel safe when using electronic products.

Reduction of metal poisoning

A RoHS compliant PCBA helps to minimize any form of metal poison. Heavy metals such as mercury and lead have a negative effect on humans and can damage their nervous system. Also, these metals affect the reproductive system, and kidney. Consumption of lead via contaminated water will minimize the functioning of body organs like ankles and fingers.

As more electronic manufacturers comply with the RoHS directives, many electronic consumers are now purchasing lead-free electronic products. In the past, consumers dispose obsolete electronic products in landfills. This could be very poisonous to ground water. The RoHS directives forced electronic manufacturers to restrict the use of harmful substances and as such, this reduced metal poisoning in the environment.

Enhanced product safety

The implementation of RoHS directives improved the safety of electronic products. Electronic consumers are now guaranteed of the safety of their product. Since these products are free of harmful materials, this gives users more peace.  Therefore, the sales of RoHS compliant PCB assembly have increased and this board is now widely integrated in electronics manufacturing.

Increased thermal properties

Research has proved that a RoHS compliant PCB assembly features better thermal properties compared to their leaded PCBA. Also, this RoHS PCBA can tolerate temperatures which range from -45 degrees Celsius to 145 degrees Celsius. These days, circuit board manufacturers are integrating advanced halogen-free laminates. These laminates have increased the thermal stability of circuit boards to about 300 degrees Celsius.

How do you Check if a Material is RoHS compliant?

According to the RoHS directives, the PCB manufacturer needs to tender a certificate of compliance. You can check if a material complies with the RoHS directive by using he X-ray fluorescence measurement instruments. These instruments offer material analysis. This test is very important as regards RoHS regulations. Also, it is a simple and fast way to evaluate elemental concentrations in a PCB material.

Electronic manufacturers can tender a Declaration of Conformity to prove their compliance with the RoHs directives. This declaration indicates that a manufacturer meets all the requirements of RoHS directives. Claiming this declaration means the organization is assuming the responsibility for RoHS compliance.

The Declaration of Conformity will indentify information about your organization and the product. This document needs to be signed by you. Also, some third-part companies can perform tests for the product of the company to confirm compliance with the RoHS directives.

The RoHS compliance testing is crucial for electronic manufacturers and distributors who need to sell or export their electronic or electrical products to the European Union. This test will verify the amounts of the hazardous chemicals restricted by RoHS.

Therefore, electronic companies and PCB companies hire third-party services to test. After testing, these results are then recorded in a test report in order to declare your product complies with RoHS.

How RoHS is Impacting PCB Manufacturing Process

The RoHS directives implementation is crucial in PCB manufacturing. A large number of PCB manufacturers must comply with these directives. Therefore, these manufacturers need to ensure that their solder masks, substrate materials, surface finishes, and inks must be free of lead and other chemicals.

Furthermore, PCB manufacturers and assemblers must be sure heat sinks, discrete components, and solder joints are free of lead. The RoHS listed 10 hazardous materials. However, lead is a major concern for PCB manufacturers in terms of its replacement. These manufacturers are concerned about the greater processing temperatures related to lead-free metals. To have a clear understanding of this, let us have a brief look at the following.

Laminate preparation

Lead-free FR4 material poses some limitations during assembly. Manufacturers can opt for advanced materials like Isola FR415 since they can tolerate higher temperatures and enable electrical performance.

Other crucial properties of lead-free PCB materials used for making prepreg and laminates include CTE, T-260 & T-288, Td, and CTE. Also, the glass transition temperature determines the choice of material based on the application. The manufacturing processes of lead-free laminates are usually performed at greater temperatures than that of leaded materials.

During assembly processes, RoHS compliant PCB materials must be handle greater reflow temperatures. But, the application requirements still determines the selection of this material. Lead-free materials need to guarantee excellent electrical performance with low signal losses.

Soldermask and legend inks application

The legend inks and solder mask integrated in RoHS compliant PCB assembly have to be free of harmful materials. Also, the ink and soldermask must be able to restrict higher temperatures. There is a likelihood of discoloration at higher temperatures.

Stencil application

Here, the initial step for the process of PCB assembly is applying the stencil. Lead-free solder alloy is commonly integrated for surface mount technology, wire soldering, and wave soldering.

Application of RoHS surface finishes

Not all surface finishes are RoHS compliant. However, the availability of RoHS compliant surface finishes like electroless nickel immersion gold, palladium, plated nickel gold, and immersion silver will get rid of the need for surface finishes with lead.

RoHS Directives for Flame Retardants

In PCB manufacturing, flame retardants, also known as FR-4 are commonly used. flame retardants minimize heat concentration and get rid of or delay flashovers. The RoHS directive impacts flame retardants integrated in resin system. This directive prohibits some particular type of flame retardants. These are brominated flame retardants. They comprise polybrominated biphenyl oxices and polybrominated biphenyls.

Using tetrabromobisphhenol A to Brominate the epoxy resin is the best way to achieve flame retardancy. Bromine releases when tetrabromobisphhenol A reacts in the epoxy resin. The RoHS directive doesn’t prohibit the use of tetrabromobisphhenol A. However, it doesn’t permit these substances from being released in the environment.

Frequently Asked Questions

What is a CE RoHS marking?

According to the Restriction of Hazardous Substances (RoHS) directives, all new electrical and electronic equipment available on the EU market must have the CE mark. The CE RoHS marking is a self-certification designed to indicate conformity. This mark doesn’t only indicate compliance with RoHS, but it also indicates compliance with all EU legislation. Having the CE mark means an electronic manufacturer is responsible for compliance with EU legislations applicable to its product.

What are products need RoHS testing?

Some products need RoHS testing before they can become available in the EU market. The categories of these products are automatic dispensers, small household appliances, monitoring devices, consumer equipment, IT and telecommunications equipment, medical devices, sport equipment, electrical and electronic tools, and other electronic devices.

What are the exemptions of RoHS?

Some exemptions were published by the European Commission. The restriction of lead, Cadmium, Hexavalent chromium, Mercury, and more isn’t applicable to toys. This is because toys are subjected to some other restrictions. For instance, the REACH deals with toys. REACH and RoHS can be quite confusing, but they have their differences.  

What Does Waste of Electronic and Electrical Equipment Mean?

WEEE means Waste from Electrical and Electronic Equipment. The WEEE directives regulate how electronics products are discarded. All electronic products for the European Union (EU) market must comply with WEEE. These products must have the “Wheelie Bin” mark.


When it comes to environmental protection, Europe is fully involved. The European Union has been the leading country that makes effort towards the achievement of environmental safety. The RoHS directive has been updated a lot of times. It is crucial for electronic and PCB companies to comply with this directive in order to stay relevant in the market.

According to the RoHS directive, any electronic or electrical product must not include substances such as mercury, polybrominated biphenyls (PBB), mercury, hexavalent chromium, Octa PBDE, Cadmium, and lead. This directive must be applied in all electronic or electrical products manufactured and sold in the European Union countries.




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