Episode 11: Safe and reliable plating technologies

Environmental regulations for safe manufacturing

For safe and reliable production

There are various regulations, laws and rules around the world that aim to protect the environment. In Europe in particular, regulations and other measures are being established to lower the burden on the environment and companies are being required to respond to them. The following are representative examples of this.

  • RoHS Directive
    In principle, it is not possible to sell any electrical or electronic components that contain lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls (PBB) or polybrominated diphenyl ether (PBDE).
  • ELV Directive
    This prohibits the use of lead, mercury, cadmium and hexavalent chromium in the materials and components used on automobiles.
  • WEEE Directive
    To reduce waste, products put on sale must be made easier to recycle.
  • REACH regulations
    In principle, all chemical substances must be registered, evaluated, authorized and restricted by the European Chemicals Agency.

These are all regulations related to items manufactured or sold within Europe. Even if the manufacturing takes place in a different region, compliance with the rules is necessary if the products are to be exported to Europe.

Of course, plating technology must also respond to these regulations.

From here, let’s look at the measures taken in plating for the environment.

Five pillars of safety and security in plating

Technological innovation to solve conventional problems

In order to comply with the environmental directives and regulations, plating has used technological innovation to solve the issues. The main examples of this are:

  • No inclusion of heavy metals
  • No inclusion of hexavalent chromium
  • No inclusion of formalin
  • No inclusion of cyanide
  • No inclusion of PFOS

In conventional plating, these were all important and essential substances. However, technologies to replace them have been developed and the use of these new technologies is beginning. Let’s look at each one of these.

Plating that does not include heavy metals

The development of plating solutions that comply with environmental regulations

In the electroless plating performed up until now, heavy metals (such as lead) were contained in the plating solution itself. Also, although the amount was small, there were also some heavy metals included in the plated film. When this is the case, there are problems with the environmental regulations when items are disposed of. It was therefore desirable to develop an electroless plating solution that includes no heavy metals.

The development of plating solutions progressed from 2000 onwards and technology was established to eliminate the use of all heavy metals in electroless plating except the metal to become the plated film (i.e. to have no metal except nickel when performing electroless nickel plating). In a lot of the electroless plating performed today, there is no inclusion of heavy metals in either the plating solution or the plated film.

Also, when this plating solution that does not contain heavy metals is used, it becomes easier to dispose of the plating solution after it has been used. This plating is therefore also kinder on the environment in this regard.

Environmental measures for chrome plating

Advances in the technology for environmentally-friendly

Chrome (Cr) is common in the natural world and it is a substance that is often used in plating because it is has stable properties and does not easily rust. The types of chrome are trivalent chromium (Cr+3) and hexavalent chromium (Cr+6). Some people may think that chrome is a harmful substance, but trivalent chromium is actually an essential mineral component for the human body and it is sold in dietary supplements. However, hexavalent chromium is strongly toxic and has an extremely large effect on the human body if it is inhaled or simply touched. The same chromium displays completely different physical properties.

Films created with chrome plating (metallic chrome layers) are safe for both the human body and the environment and are not included in the regulations such as the RoHS Directive. However, if hexavalent chromium is used in the manufacturing processes for the chrome plating, then it is necessary to sufficiently clean the completed surface to ensure that the processing liquid does not remain as a residue.

So, why is hexavalent chromium used?

Hexavalent chromium is cheap and makes chrome plating easy, so it is easy plating for a manufacturing plant to handle. On the other hand, with trivalent chromium plating, the preparations and the management of the solution are difficult and it is a more expensive method, which is why it has not been used in the past. In addition to this, with trivalent chromium plating, there is sometimes hexavalent chromium formed in the solution during the work, so it is a difficult substance to perform plating with.

The development of chemicals for trivalent chromium and the adjustment of the processing conditions for the plating are proceeding so that it is now becoming easier to perform trivalent chromium plating and there are expectations for further developments in the future.

Plating that does not use formalin, cyanide or PFOS

Plating is evolving to be kinder on the environment

In addition to heavy metals and chromium, plating also uses other substances that can affect the environment and the human body. Development is also ongoing for alternative technology that does not use these substances.

  • Formalin is used in many applications such as disinfectant, insecticide, adhesives and paints and its unique odor is probably familiar to many of you. It is highly toxic and care is required in its use. The formalin used in construction materials has been given as one of the causes of sick house syndrome. In plating, it is used widely as the reducing agent for electroless copper plating. The development of a new reducing agent for electroless copper plating is now underway and it will probably not be long before a reducing agent other than formalin becomes the most common.
  • Cyanide, which is also known as cyanogen, is used in compounds such as potassium cyanide and sodium cyanide. It is an extremely toxic substance. In metal plating, it is used as a complexing agent. However, plating methods using new substances are already becoming the mainstream in some sectors and are spreading throughout the metal plating industry.
  • PFOS refers to a refractory organic fluorine compound surfactant and is a widely used type of surfactant. “Refractory” means that the substance cannot be easily broken down in the natural environment and most of it will remain unchanged. These substances have a harmful effect in the human body and also remain inside the body. However, these substances have been viewed as a problem since the 2000s and they are no longer manufactured. Substitute chemicals have therefore come into use.

In this way, research and development on alternative technologies has been performed for the substances that were once thought to be essential for plating and the burden on the environment has been reduced even further.

Environmental measures in plating workplaces

The move to workplaces that save energy and are beneficial for the working environment

When performing plating, especially electroless plating, one key point is the basic rule of chemistry that “the reaction speed approximately doubles when the temperature rises by 10 °C.” If we examine the case of electroless nickel plating, the plating is normally performed at the high temperature of 90 °C, so the following issues arise.

  • Energy is required to raise the temperature of the plating solution.
  • When the temperature of the plating solution is raised, it tends to evaporate more, so it becomes necessary to replenish the chemicals and water.
  • Water vapor containing the chemical solution is generated in the working environment.

In this way, consideration is needed for energy-saving and the working environment.

To solve these problems, the development of chemicals has proceeded so that plating can be performed at a low temperature. At present, processes have been developed to make plating possible at around 50 °C. Also, an increasing number of the machines to perform the plating are becoming the sealed type. This is contributing to improvements to the processing efficiency and to the working environment.

In this way, the progress in plating technology is not only responding to environmental problems, but also helping to improve the working environment.

The development of sustainable technologies that will remain necessary

Plating has excellent performance and functions and it is used in a wide range of situations. From now onwards, it will be necessary to realize both quality and environmental performance and the measures to respond to these issues are progressing.

Plating is an essential part of modern life and industry and the technology itself must be a sustainable one.

The evolutionary progress will continue on forever so that plating can go on to be a technology that is in even greater demand than it is today.