The Importance of a Halogen-free Printed Circuit Boards

During the development of printed circuit boards, there are many compounds and elements that are utilized for a variety of purposes. During the early days of PCB development, many toxic compounds were used as either a cost-saving aspect of manufacturing or because of the specific, helpful nature of the element. As humanity develops an increased understanding of the threats that past materials present to life in today’s world, manufacturers are changing methods and finding new materials that don’t pose a threat to individuals working with such creations.

Common compounds that are used in PCB developments belong to the family of Halogen elements. Although the composition themselves provide certain benefits to the development of electronics, they are harmful to human life in one way or another.

These elements are:

– Flourine

– Chlorine

– Bromine

– Iodine

– Astatine

While there is still debate on the toxicity of halogens within PCB development, there are two primary elements that constitute the general consensus of a halogen-free circuit board. These two are chlorine and bromine. Each provides a specific benefit to the overall safety and functionality of electronics but pose a threat to the continuity of life for humans and nature.

Functionality of Chlorine

The element chlorine is used in a wide array of products. It is a prime ingredient used in bleaches for cleaning as well as sterilizing pools to kill off bacteria. In small and diluted doses, this element can help in the protection of life from illnesses developed by virus and bacterial strains. However, dangerous concentrations of chlorine can pose certain health risks.

Some of the symptoms of chlorine exposure include:

– Blurred vision

– Uncontrollable coughing

– Severe skin irritations and pain

– Nausea

– Difficulty breathing

– Burning sensation in nose, throat and the eyes

Continued exposure to chlorine can cause severe complications such as pulmonary edema, or consistent fluid in the lungs. According to a study published in a previous edition of Pediatrics, children are eight times more likely to develop asthma while swimming in Chlorine treated pools as opposed to not (1). The effects of chlorine including the disposal and destruction of related products are prompting the Restriction of Hazardous Substances directive to consider placing chlorine on the list for electronic compliance. Not only is it a threat to human life, but it is a toxic element that can cause severe damage to an eco-system.

How is Chlorine Used in Electronics?

Generally, there are many uses for chlorine-based components when developing electronics. Although the element was initially an effective tool for development, the threat it poses can be difficult to bypass.

Some of the uses of this material include:

– Polyvinyl Chloride coatings for cables and wires

– Chlorinated flame retardants to protect components and devices

– Trichloroethylene solvents used in semiconductor development

– Trichloroethane solvents to clean computer chips

Functionality of Bromine

Although bromine doesn’t have the notoriety and popularity with household products as its companion, it is still used in a variety of ways that many people may not consider. It, too, is used in water treatment for swimming pools and hot tubs as well as controlling bacterial growth and algae within industrial processes. It is used in the agricultural industry as a pesticide. Bromine is also being tested for use in batteries for electric vehicles. Coincidentally, bromine is also a component of many pharmaceuticals in the health industry.

However, high concentrations of bromine can cause:

– Nausea

– Watery eyes

– Skin irritations and burns

– Headaches and dizziness

Sustained exposure to bromine can cause brain damage as well as kidney failure due to systemic poisoning. The blood pressure of an individual could drop to intolerable levels for internal organs, assisting in overall physical dysfunction. For those that continuously breathe in bromine, there is an increased chance of long-term lung problems of varying degrees.

How is Bromine Used in Electronics?

Currently, many brominated compounds are restricted by the RoHS directive. Primarily, these chemical compositions serve to act as flame retardants generally used in plastics for the chassis of electronic devices as well as on the PCB itself. Although it serves the purpose of protecting against further damage from the onset of a fire, it’s still a dangerous component to work with especially when inhaled as fumes from a melting plastic chassis.

According to PCI-SIG, the special interest group responsible for universally specifying Peripheral Component Interconnect buses for computer systems, the printed circuit motherboard constitutes the largest contribution of weight from halogen materials. In light of the weight distribution of this component, it is imperative for IT support staff to consider safe methods for disposing of upgraded motherboards in computer systems.

Environmental Impact of Chlorine and Bromine

The importance of halogen-free components can be viewed as an effect of the aftermath from disposal of various electronics. While merely handling a PCB will more than likely not affect an individual, it is the incineration and destruction of components that pose the more serious threat. Dioxin is a compound that forms when chlorine-based components are brunt with the addition of hydrocarbons. According to the United States Environmental Protection Agency, dioxin is one of the most toxic chemicals currently known to exist. (2)

Dioxin has been confirmed by the EPA to cause cancer within humans (3). This means that incineration of PCBs developed with chlorine-based products has a strong likelihood to cause fatal injuries to individuals simply breathing in the fumes produced. In January of 2001, dioxin was upgraded to be a known human carcinogen. A couple of years later, it was determined that there is no known tolerance level or safe dosage that will not ultimately cause cancer. A study completed in 2012 has reassessed the dangers of dioxin which have been found to be within the tissues of animals that humans consume.

The toxicity that is created from improper disposal could put individuals and eco-systems in great jeopardy. Precious metals aside, choosing a halogen-free product can keep your developers and future technicians safer from experiencing health complications due to exposure.