All About Flex: FAQs on RoHS for Flex Circuits


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In 2003, the European Union (EU) adopted a standard called the Restriction of Hazardous Substances (RoHS), which restricts the use of certain materials in electronic products and electronic equipment. The intent is to reduce the environmental impact of known hazardous materials and has driven changes in manufacturing processes and materials used to manufacture a wide array of electronic products. Answers to some frequently asked questions are included below.

What does RoHS do?
The Restriction of Hazardous Substances (RoHS) restricts the use of the following materials:

  • Lead < 1000 ppm
  • Mercury < 100 ppm
  • Cadmium
  • Hexavalent chromium < 1000 ppm
  • Polybrominated biphenyls (flame retardants commonly found in appliances) < 1000 ppm
  • Polybrominated diphenyl ethers (PBDE, flame retardant often used in PCBs) < 1000 ppm
  • Bis(2-ethylhexyl) phthalate (DEHP, materials used to soften the plastic on wire insulation) < 1000 ppm
  • Dibutyl phthalate (DBP, materials commonly used to soften PVC and vinyl insulation on electrical wires) < 1000 ppm
  • Diisobutyl phthalate (DIBP) (Materials used to soften PVC and vinyl insulation on electrical wires) < 1000 ppm

What products are applicable to RoHS?
Currently, the following products are covered by RoHS:

  • Large household appliances (e.g., refrigerators and air conditioners)
  • Small household appliances (e.g., microwave ovens and coffee machines)
  • Computing and communications equipment (e.g., laptops and tablet computers)
  • Consumer electronics (e.g., LED screens and Blu-ray players)
  • Lighting (e.g., LED lamps and light bulbs)
  • Power tools (e.g., drills and blowers)
  • Electric toys and sports equipment (e.g., fitness bikes)
  • Automatic dispensers (e.g., vending machines)
  • Medical Devices (e.g., pulse rate monitors)
  • Semiconductor devices (e.g., breathalyzers)

What products are not covered by RoHS?
The following products are currently exempted from the ROHS directive:

  • Military equipment
  • Equipment designed to be sent into space
  • Part of another type of equipment that is out of scope
  • Large-scale stationary industrial tools
  • Large-scale fixed installations
  • Transport
  • Non-road mobile machinery for professional use
  • Active implantable medical devices
  • Photovoltaic panels
  • R&D equipment for B2B only

Are flexible circuits covered by RoHS?

Yes, flexible circuits go into many of the electronic products covered by RoHS. The most common electronic materials covered by the RoHS restrictions are solders and components containing lead. Flame retardant adhesives used in the laminates and specific electronic components and batteries that may contain cadmium, or mercury are also restricted. Fortunately, there are RoHS compliant substitutes for most of these components and materials.

What EU countries require RoHS compliance?

Basically, all the countries in the EU, which includes: Austria, Belgium, Bulgaria, Cyprus, Czech Republic/Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden and United Kingdom. The vote by Great Britain (Brexit) is one example of the complication created by their vote to leave the EU. Who knows how this will affect their RoHS status?

Are there any non-EU countries that have regulations similar to RoHS?

The following countries have restrictions in place or at least pending legislation that have restrictions similar to RoHS: Canada (Province of Alberta), China, India, Japan, South Korea, Switzerland, Taiwan. Regulations in the United States are primarily by state.

What are the penalties for non-compliance?
Penalties will vary from country to country. Common penalties could include fines, banning product from the market or even imprisonment depending on jurisdiction.

How is RoHS enforced?

In most cases an examiner would review the compliance documentation; however, in some cases the actual product is inspected or tested for compliance.

Why is enforcement of RoHS different for each EU nation?

RoHS is a directive and not a regulation. The main difference being that a directive only applies to the end result and does not specify how it is enforced or what penalties will be enacted for non-compliance. Each country in the EU is allowed to use its own discretion in how it will assure compliance.

Is China RoHS the same as EU?

Previous to July 2016, the China RoHS was considered less restrictive that the EU version, as well as having a much different scope, although there were cases where China’s version was more restrictive. Additionally, many violations would be allowed provided the documentation accurately stated the noncompliance. China RoHS 2 took effect in July 2016 and the overall scope more closely resembles EU RoHS. There are still some allowances for noncompliance if the documentation accurately states the violation. The general consensus is that China RoHS applies to products imported into China, but products built in China might not be RoHS compliant.

How do you prove compliance with RoHS?

One way to demonstrate compliance is to build a robust document tree that applies to all components and products used. This would include certification of compliance documentation from suppliers and documentation relating processing and assembly. Another way would be to submit a representative product to a certified third party testing service to analyze and document the materials in your product. This method would still require compliance documentation that the products are the same as the tested sample. There are also consulting companies that will work the producers to ensure a RoHS compliant product and process.

What flexible circuit surface finishes are RoHS compliant?

Most surface finishes are applied to bare copper and act as solderability preservatives or switch and connector contact surfaces. The following surface finishes are common and meet RoHS requirements:

  • Lead-free solder
  • Electrolytic tin plating
  • Electroless tin plating
  • Silver immersion
  • Hard gold over nickel
  • Soft gold over nickel
  • Electroless nickel immersion gold (ENIG)
  • Organic solder preservative (OSP)

Does the United States require RoHS compliance?

There is no federal regulation pertaining to RoHS, most of the regulations relating to electronic products are enacted by individual States. Thus far California has the most restrictive regulations dealing with hazardous materials in electronic products. Electronic devices containing toxic metals may not be manufactured, sold, or imported into California. There are other States that have enacted RoHS related legislation or have pending legislation. Currently, these include: Colorado, Connecticut, Florida, Hawaii, Illinois, Indiana, Louisiana, Massachusetts, Michigan, Minnesota, Montana, North Carolina, Nebraska, New Hampshire, New Jersey, New Mexico, Nevada, New York, Ohio, Oregon, Rhode Island, South Carolina, Tennessee, Texas, Virginia, Vermont, Washington, and Wisconsin.

What impact has RoHS had on flexible circuits and PCB manufacturing?

In early 2000, many lead-free soldering substitutes were emerging. There was significant concern about reliability of lead-free solder as it did not process as well as the classical tin-lead solder and had not been exposed to the reliability testing and body of evidence accumulated with tin/lead. This lead to the exemption granted many military and medical products. Of course the most common 63-37 tin-lead product had been in use for many decades. Manufacturers and material suppliers have made many improvements over those years, which has resulted in efficient and robust processes. Today processes using lead free solder are robust enough to allow for defect free soldering.

Dave Becker is vice president of sales and marketing at All Flex Flexible Circuits LLC.

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