What Is RoHS Compliance In PCB？

RoHS stands for Restriction of Hazardous Substances. It is a regulatory standard that restricts the use of harmful or hazardous substances in electronic components, including printed circuit boards (PCBs). All manufacturers er required to adhere to these regulations. On the other hand, you as a buyer should also be keen on the RoHS of the PCB that you want to buy. It will determine the safety of the boards and whether you should use them for your project.

In this guide, I am going to do a complete breakdown of all you should know about RoHS compliance in PCB. In the end, you will be in a perfect position to apply this knowledge when buying printed circuit boards for your project.

Motivation behind RoHS

There are two key motivating factors behind RoHS compliance in printed circuit boards. These are health and the environment. The regulation should address key areas of concern in the health and environmental sectors of life. Substances such as lead, mercury, and many others that are found on printed circuit boards are deemed dangerous to health and the environment, especially when they exceed a specific threshold.

What substances are restricted by RoHS?

Here are some of the substances that are red-flagged under RoHS for PCBs:

• Lead (Pb)
• Mercury(Hg)
• Polybrominated diphenyl ether (PBDE)
• Cadmium (Cd)
• Polybrominated biphenyls (PBB)
• Hexavalent  chromium (Cr6+)

The maximum threshold of the above substances in PCBs is 0.1%  beyond that, the PCB will be deemed to have violated the required standards and buyers are advised to avoid such.

Since RoHS standards have been continuously evolving, more materials have been added over time.  For example, the RoHS2 restricted  the use of other substances such as :

• Diisobutyle phthalate (DIBP)
• Dibutyl phthalate
• Bis (2-etheylhexy) phthalate (DEHP)

RoHS Scope and Exemptions for PCBs

What areas of OCB manufacturing are covered by RoHS and which ones are exempted from these regulations?

Some of the electronic devices that are covered include:

• Devices that rely on electric and electromagnetic fields for proper functioning
• Devices that generate and transmit electromagnetic fields
• Devices whose voltage does not exceed 1000 volts for the AC and 1500 volts for the DC

Technically, the above three scopes tend to cover a broad array of electronic devices and appliances. Some of the common devices include household appliances, IT equipment such as computers and servers, measuring instruments, power tools, lighting equipment, military equipment, industrial equipment, aerospace devices, power tools, and medical devices among many others.

Most of the devices and products were added through the RoHS2 which allowed for specific applications to be exempted from the regulations. Some of the exemptions include lead that has a high melting temperature, lead in glass, lead in ceramic materials, lead in power storage devices, and lead in computer servers.

RoHS requirements for PCB manufacturing

PCB assembly and manufacturing are fully covered by the scope of RoHS2. This is because a complete printed circuit board comprises numerous electronic components. Each component is designed to perform a specific function in the circuit board and at the same time has a unique working mechanism.

RoHS compliance takes center stage in all the key steps of PCB production processes which include sourcing of the materials, manufacturing, assembling, fabrication, and even during the PCB testing process.

Under the RoHS compliance, here are some of the key requirements that should be implemented during the PCB manufacturing process:

PCB materials

• The base materials such as FR-4 should be devoid of all the brominated flame retardants such as PBDE and PBB
• Ceramic substrates for the PCBs should not have restricted phthalates
• Prepreg bonding films in the PCBs should not contain any brominated compounds

PCB soldering and plating

Some of the RoHS compliance regulations for PCB soldering and plating processes include:

• Use lead-free solder alloys such as tin-silver-copper instead of lead solders
• Any type of solder flux that is used should not contain any prohibited substances
• For the plating, ensure that you use alternative materials such as immersion silver, OSP, and ENIG
• All The surface finishes should not have hexavalent chromium and cadmium plating

Identification and documentation

How do I tell that the PCB that I want to buy is fully RoHS compliant?  In most cases, printed circuit board manufacturers are required to label the boards properly for easy identification. This is where the essence of documentation comes in.  PCB manufacturers, assemblers, and fabricators should include all the required markings and labels on the PCBs for easy identification. Buyers should be able to tell whether the PCB  is fully compliant with the required PCB standards without any struggles. Markings and labels such as “RoHS” and “Lead-Free” are used to indicate that the printed PCB is RoHS-compliant.

Beyond the labeling, test documentation should be availed to verify the status of the printed circuit board. This is usually accompanied by a Certificate of Conformity.

Testing for PCB compliance

When it comes to the PCB supply chain, distributors such as Rantle East Electronic have a role to play in ensuring that customers get PCB-compliant products. One way of doing this is by conducting vigorous tests on their printed circuit boards. Usually, such distributors have advanced RoHS analyzers such as X-ray analyzers and XRF metal analyzers to screen the PCBs for the presence of toxic materials. Most testing tools are powerful enough to unravel the presence of lead and all the elements that are prohibited by the PCB regulations.

Conclusion

RoHS is one of the premium safety and environmental regulations that PCB manufacturers should follow when designing and manufacturing their products. It has been around for decades and all the key players in the industry have strongly adopted it. All the reputable PCB manufacturers have integrated RoHS into their internal manufacturing operations.  Also, it has been undergoing continuous changes, improvements, and refinements to the level that it is today.

As a reputable PCB distributor, we strongly adhere to the RoHS compliance standards. We have a strong team of testers and inspectors who inspect every PCB to ensure that it does not contain any hazardous elements. You can trust us in case you are in the market looking for RoHS-compliant printed circuit boards.