Safety should be an utmost concern when manufacturing a printed circuit board. PCB manufacturing shouldn’t jeopardize the health and safety of people. Therefore, PCB assemblies process need to consider environmental safety. Also, some substances used in manufacturing printed circuit boards are hazardous. Therefore, there should be some restrictions on how these materials are widely used in PCB manufacturing.
The RoHS directive helps to regulate the use of harmful substances in PCBs. All PCB manufacturers need to take responsibility for the products they manufacture. Some circuit boards are specially fabricated without the use of certain harmful substances. The RoHS directive sees to the manufacturing of PCBs without some restricted materials.
What Does RoHS Compliance Mean?
The European Union parliament passed bills that influenced the electronic industry. The Waste Electrical & Electronic Equipment (WEEE) was the first legislation passed. Also, the second one was the Restriction of Hazardous Substances.
RoHS prohibits the use of any restricted materials to manufacture electronic or electrical equipment. This legislation became effective in 2006. Also, the directive aimed to ban the utilization of some harmful materials in producing electronics and circuit boards. Any original equipment manufacturer (OEM) that sells electronic products to European customers must adhere to RoHS compliance.
These materials include:
- Mercury
- Cadmium
- Polybrominated biphenyls (PBB)
- Lead
- Polybrominated diphenyl ethers (PBDE)
- Hexavalent chromium
- OCta PBDE
- Phthalates
Any printed circuit boards must not contain any of the materials listed above. Also, the RoHS compliance includes the type of surface finish. The PCB surface finish must not feature any of these materials. Also, RoHS bans the use of lead in manufacturing electronics within countries under the EU.
Traditional solder usually comprise 40% lead and 60% tin. Also, manufacturers used solder in applications within electronics and engineering. This means that a good amount of lead have ended up in landfills. Lead contains a high level of toxicity which is harmful to humans and wildlife. Also, lead is toxic to food sources. Therefore, this prevents the spread of this toxicity, the RoHS directive came into picture.
At first, the industry was resistant to these changes due to the initial lack of a good alternative to lead. Also, there were reports that lead-free solder caused delamination to circuit boards. However, the RoHS go better alternatives to lead. Therefore, various industries now adhere to RoHS compliance.
Factors that Affect the Selection of RoHS Material
PCB manufacturers need to ensure the reliability of a circuit board while choosing a base material. Also, these key properties help to select the base material of a circuit board
Moisture absorption
The pressure of water becomes higher at lead-free assembly temperature. During thermal cycling, absorbed moisture can be volatile. Also, this can further cause delamination or voiding. PCBs that pass through lead-free assembly testing may have some defects after storing them in an uncontrolled environment. Therefore, when choosing materials for PCBs, manufacturers should consider this property.
Glass transition temperature
This property measures the point at which a material transforms form a glassy, rigid state to a liquid-like state. Also, as glass transition increases, several properties change. For RoHS material, PCB manufacturers should consider this property.
Delamination time
Delamination time relates to the adhesion between material components. Moisture absorption rate and thermal expansion can affect results. It is crucial to treat the internal copper surfaces for multilayer PCBs.
Coefficients of thermal expansion
CTE values above glass transition are much greater than below glass transition. Also, Z-axis expansion triggers stress on plated vias. The greater lead-free assembly temperatures lead to more expansion for a particular material.
Importance of RoHS PCB Assembly
RoHS compliant PCBs are specifically designed for the safety of our environment. Maintaining the green future is the greatest benefit of these PCBS.
User safety
A RoHS compliant guarantees the safety of users. Most PCB manufacturers adopt RoHS compliance. Therefore, users are guaranteed that the product they utilize contains no mercury or lead. Also, this has tremendously increased the popularity and sales of the products.
Enhanced thermal properties
Lead-free circuit boards feature great thermal properties. Therefore, they perform better than their leaded counterparts. These circuit boards can resist temperatures between -45oC to 150oC. These days, manufacturers are making use of halogen-free materials that have improved thermal stability.
Reduces metal poisoning
Electronic consumers are discarding obsolete electronic devices in landfills. Also, these devices feature hazardous materials which can result in severe poisoning. Despite recycling, these devices feature harmful substance in them. Also, the RoHS has compelled OEMs to minimize the use of hazardous substances. This has reduced the effect of these materials on the environment.
Product reliability
Most popular electronics manufacturers adopt RoHS directive. Also, customers are now guaranteed of the reliability and safety of products. Therefore, this has helped to improve the reputation of brands that produce RoHS compliant circuit boards.
Various improved testing methods
RoHS compliant circuit boards pass through improved testing methods. Also, RoHS PCBs use lead-free solder finish. Chemistry methods and spectroscopy are two common methods used by RoHS. These method determine the concentrations of restricted substances.
Applications of RoHS Compliant PCB
RoHS compliant PCB is widely used in several applications. Environmental safety has become a major concern for most industries. Also, the electronic industry has sought for ways to make electronic devices more environmentally friendly. Therefore, RoHS compliant boards offer a lasting solution to this challenge.
Medical
RoHS compliant PCBs are widely used in the medical industry. Also, medical devices require the use of safe PCBs. The restriction of specific hazardous materials is applicable to medical devices. Also, these circuit boards are useful for producing safety-critical devices. The directive 93/42/EEC is a requirement for medical devices.
Telecommunications
RoHS compliant circuit boards are available in telecommunication devices. These boards have helped to prevent environmental related risks.
The RoHS directive stresses the need for the use of RoHS compliant PCB in consumer electronics. Therefore, consumer electronics like televisions and mobile phones feature lead-free PCBs. These lead-free PCBs are safe for the environment.
RoHS Compliant Surface Finishes
Not all PCB surface finishes are RoHS compliant. A RoHS PCB must be completely free from any hazardous materials listed by the RoHS directives. Lead-free finished add to the physical capabilities of PCBs. Some PCB surface finishes are RoHS compliant. These surface finishes include:
Immersion tin is a lead free PCB surface finish. Therefore it is RoHS compliant. Also, this lead-free surface finish is suitable for fine pitch components. The immersion tin is a deposit if a layer of tin. Therefore, immersion tin serves as a great alternative to lead-based finishes.
Immersion silver
This is another popular lead-free PCB surface finish. Immersion silver offers EMI shielding. Also, immersion silver is ideal for membrane switches and aluminum wire bonding.
Organic solderability preservatives (OSP) surface finish has gained popularity over the years. This is because of its interest in lead-free processes. Also, OSP produces a thin and protective layer on the copper surface of circuit boards. This layer shields the circuitry from any oxidation during PCB assembly.
Electroless nickel immersion gold is another lead-free surface finish. ENIG features two main layers of metallic coating which are electroless nickel and immersion gold. Also, ENIG is RoHS compliant since it features no lead. Therefore, ENIG is a highly preferred surface finish among PCB manufacturers.
Lead free HASL
Lead-free HASL complies with the RoHS directives. Unlike leaded HASL, lead-free HASL comprises no lead. This surface finish option offers excellent solderability and shelf life. Also, it is ideal for lead-free soldering.
ENEPIG
Electroless nickel electroless palladium immersion gold (ENEPIG) is a lead-free PCB surface finish. Also, this surface finish features nickel, palladium, and gold. The palladium layer shields the nickel layer from any corrosion. ENEPIG is more affordable than ENIG since it doesn’t comprise gold.
Impacts of Non-RoHS Compliant PCBs
Non-RoHS compliant PCBs or electronic parts do not only affect the customer, but also affect the supplier. The production of non-compliant PCBs affects both the manufacturer and the customer. Before these electrical and electronic products get to the final consumer, there is a need for shipping and packaging.
Also, the packaging process puts the lives of employees at risk. This is because they come in contact with the harmful substances. Also, before these parts got to these employees, the manufacturer has been already exposed to this toxicity.
However, the final destination of the non-RoHS part isn’t the consumer’s place. After the product has become obsolete or damaged, the product ends in a landfill or recycling center. While the recycling facility might be safer, the landfill isn’t safe. Since it is just a hole in the ground, water can move any amount of the hazardous substances. This will end up polluting the ground as time goes on.
Furthermore, hazardous materials don’t degrade and they may continue to pass through the ground. In the long run, they will end up in underground water or the ocean. Therefore, this will further pollute food sources and wildlife.
Tuna is a good example of such pollution. This long-lived fish consumes hazardous substances in water. Therefore, it comprises trace amounts of lead and mercury. This is a result of dumping hazardous substances in oceans where long-lived fish have time to absorb these substances. One way or the other, hazardous substances will always find a way into our environment.
How to Test Products for RoHS Compliance
You might be wondering how the RoHS directive tests electronic products to ensure compliance. Well, this directive ensures it tests electronic products in a lab. Therefore, this procedure will help to determine the amount of the restricted harmful substances. The RoHS directive conducts these tests:
- X-ray fluorescence spectroscopy (XRF) utilizes X-ray to evaluate the levels of alloys and metals within a product. This test is usually used for bromine.
- Scanning Electron Microscopy (SEM/EDX) identifies lead-free solder in the joints of a product.
- Atomic Absorbance Spectrophotometry (AAS) determines the amount of mercury and lead in a product.
- Fourier Transform Infra-Red Spectrophotometer (FTIR) detects polymer in an electrical or electronic product. It identifies bromine found in form or PBDE or PBB.
Frequently Asked Questions
How long does a RoHS certificate stay valid?
A RoHS certification will stay valid for a period of five years. There may be a need for early re-certification if an electronic product goes through significant changes in materials or design.
Is RoHS applicable to plastics?
If an electronic or electrical device comprises a plastic component, the plastic must be RoHS compliant. This is very important because some plastic materials contain toxic substances.
Is RoHS compulsory in Europe?
In all EU countries, all electronic or electrical equipment must be RoHS compliant. However, RoHS is implemented differently in each EU member state. Therefore, electronics manufacturers importing their products must be familiar with the individual measures implemented by each country.
Are there any exemptions from RoHS?
Yes, some products are currently exempted from RoHS compliance. Also, these exceptions cover different types of industrial, medical, and military equipment. Parts of electrical equipment available in the market before July 1, 2006 are exempt from RoHS. However, spare parts of newer electrical or electronic equipment are not.
Are WEE and RoHS related?
Yes, WEE and RoHS directives are related. This is because the two directives focus on the safety of the environment. The WEE focuses on encouraging electronic design with environmentally-safe recovery and recycling. On the other hand, the RoHS focuses on regulating the amount of harmful substances used in electronics manufacturing. Therefore, RoHS regulates the harmful substances in electronic products while WEE focuses on these products’ disposal.
Conclusion
RoHS compliant PCB assemblies are safe for use in electronic manufacturing. Also, RoHS circuit boards doesn’t compromise the quality of a printed circuit board. Lead-free PCBs can enhance the lifespan of an electronic product. RoHS compliant PCBs comprise the use of lead-free stencils and lead-free surface finish. Also, RoHS is applicable to electrical and electronic components.
Compliance to the RoHS directive helps to assure standard electrical performance in a printed circuit board. PCB assembly processes must involve the use of RoHS compliant materials and procedures.
