Sustainable PCB cleaning: helping to protect our future

They have to produce high quality boards while minimising their environmental impact, conserving energy, and protecting natural resources. All while ensuring the health and safety of their employees. 

At the same time, they must maintain their profits and meet their customers’ specifications without compromising PCB quality. Their challenge is to meet today’s short-term business goals without losing sight of the long-term impact that their operations might have on the planet or on future generations.

Increasing pressure from many sources

One area that is often overlooked but can make a big impact on sustainability goals is PCB cleaning.  For many fabricators, their cleaning processes are already well-established. However, in an effort to reduce any negative impact to workers or the planet, growing numbers of regulatory agencies across the globe are adding legislation and are more stridently enforcing ‘green’ laws around cleaning fluid use and disposal. The new regulations require more sustainable practices, and some fabricators are finding their cleaning fluids or methods are no longer suitable. Fabricators must seek out new alternatives to continue to clean effectively, but also meet the new emerging regulations, for both now and into the future.

Going green with vapour degreasing

Some PCB fabricators are considering vapour degreasing as a possible PCB cleaning method. Vapour degreasing is a safe, fast and affordable cleaning method that is easy to integrate into existing production processes. It is also an environmentally-sustainable way to clean PCBs.

A vapour degreaser heats a modern, non-flammable cleaning fluid into a dense vapour that rises through and is trapped inside the machine. The boiling fluid and vapours combine to clean and dry the contaminated PCBs inside. When the vapours reach condensing coils at the top of the machine, the coils chill the vapours back into a liquid state. This clean liquid falls into a trough and is made ready for the next cleaning cycle.

The cleaning fluid used inside the vapour degreaser is engineered with just the right characteristics (boiling point, specific gravity and surface tension) to wet every surface, getting in between and under tightly spaced and low-clearance components. It also offers high solvency which allows it to rigorously clean PCBs and dissolve stubborn flux residue. Typical cleaning cycles take as little as six to 20 minutes per batch and the boards come out clean, dry, and immediately ready for packaging or conformal coating.

Meeting emissions requirements

Modern vapour degreasing fluids use HFO (hydrofluoroolefin) chemistries to help them meet strict air quality emission regulations. They have a zero ODP (Ozone Depleting Potential) and a low GWP (Global Warming Potential).

The GWP of a cleaning fluid is a measurement of the atmospheric lifetime of the fluid or its gaseous vapours. The longer a trapped gas absorbs infrared radiation in the atmosphere, the more it may contribute to global warming and climate change. The lower the GWP number, the more climate-friendly the substance. Modern cleaning fluids typically have a low GWP of 10 or less. By comparison, outdated solvents like HFCs (hydrofluorocarbons) and HCFCs (hydrochlorofluorocarbons), had average GWP ratings in the thousands.

Modern degreasing fluids are also not classified as a hazardous air pollutant (HAP). They typically do not require National Emission Standards for Hazardous Air Pollutants (NESHAP) permits. Modern vapour degreasing fluids meet environmental directives including the U.S. Environmental Protection Agency (EPA) regulations and the European Union (EU) REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) legislation. They are also approved under the U.S. Significant New Alternatives Program (SNAP) and Toxic Substance Control Act (TSCA).

Conserved natural resources

Many of the modern sustainable cleaning fluids feature a low boiling point and heat of vapourisation. This reduces the amount of energy needed to heat the cleaner. It reduces fossil fuel consumption resulting in a lower total carbon emission and less greenhouse gas output. 

Vapour degreasers also use no water. For many years, some people considered water-based cleaning, also known as aqueous cleaning, better for the environment. However, that cleaning method is now under environmental scrutiny itself. Aqueous cleaning requires a great deal of energy to heat the water to cleaning temperature. It also consumes power to apply heat and air to dry the PCBs.

Also, as the name suggests, aqueous cleaning uses vast amounts of non-renewable clean water. It produces dirty wastewater that requires careful filtering, distillation, deionising, and osmosis prepping prior to disposal. All of this water usage and water processing negatively impacts the environment and potentially puts future populations at risk, especially in impacted areas where water is scarce.

Plus, aqueous cleaning poses some PCB cleaning challenges. It requires constant monitoring and testing to ensure the correct chemical balance of emulsifiers, saponifers and other additives. Drying can also be a challenge. In some instances, it is difficult to get the water to dry off the PCBs completely. This is especially true with densely populated PCBs or those with zero clearance mounted components. Leftover moisture can cause corrosion, dendrite growth or conformal coating adhesion issues later down the line. 

Recycle and reuse

A vapour degreaser is not only a PCB cleaner, but also a continuous recovery and recycling system. The vapour degreaser uses and reuses the same cleaning fluid hundreds of times before it needs refreshment or replacement. The vapour degreaser concentrates the soils and contaminants as it works, minimising the amount of hazardous waste generated and lowering hazardous waste removal costs.

Helping protect exposed workers

When choosing a sustainable long-term cleaning solution, worker safety is always a top priority.  Supporting worker health and safety with a sustainable cleaning fluid is paramount. It is important to eliminate cleaning fluids that could be harmful and replace them with a better alternative.

Outdated brominated and chlorinated vapour degreasing fluids like n-propyl bromide (nPB), perchloroethylene (Perc) or trichloroethylene (TCE) carry health risks and have higher toxicity levels and lower PELs (Personal Exposure Limits) than their more modern counterparts. 

The OSHA-designated time limit or PEL that workers are exposed to a chemical is far more acceptable for modern sustainable cleaning fluids than hazardous legacy solvents. The higher the PEL number, the better. The usual PEL for sustainable fluids is 200-250 ppm (parts per million).  When compared with TCE which has a 100-ppm PEL or nPB which is rated at just 0.1 ppm by the American Conference of Governmental Industrial Hygienists (ACGIH) it is obvious to see the worker safety advantages of the modern cleaning fluids.

Is now the time to change?

In Europe, both TCE and nPB are banned for industrial cleaning use. Canada has also severely restricted their use and many other countries are likely to follow. In 2020, the U.S. EPA announced nPB and TCE present an unreasonable risk to human health when used as a cleaner inside all vapour degreasers including open-top, in-line, and closed-loop models. Today, it is unknown exactly when a complete nPB and TCE ban will happen in the U.S., but many experts agree an eventual ban is certain and coming soon. So, now is the time to search out a better, more sustainable option that will meet these evolving regulations.

Added benefits of sustainable cleaning

There are many other benefits of using vapour degreasing and a sustainable cleaning fluid. Here are some other larger-scale advantages.

• Less Waste and Scrap: Using a sustainable cleaning fluid and a modern vapour degreaser improves PCB cleaning consistency. This reduces scrap and rework which lessens the number of raw materials used to complete an order. This also means fewer scrapped circuit boards go to the landfill.  
• Easier Maintenance and Recycling: Modern sustainable cleaning fluids do not require the stabilisers, scavengers or frequent acid acceptance testing required of older solvents, reducing overall maintenance costs. This also allows the fluids to be more easily recycled on-site.
• Improved Reputation: A reputation as an eco-efficient, sustainable company can interest potential employees, new customers and even investors. Being planet-friendly is a competitive business advantage.
• A More Solid Workforce: Companies with a good sustainability reputation typically attract and retain more qualified employees who are happy within their workplace. Happier workers tend to perform better and stay longer at their companies, reducing employee turnover and the costs of hiring and training.

The next steps for sustainability

PCB producers are implementing sustainable practices in a variety of other ways besides cleaning. Many are converting to LED lighting or replacing outdated air conditioning systems to reduce energy consumption. Others are installing passive solar panels or turning to wind energy as an alternate source of power to reduce their carbon footprint. Still others are adding well-developed recycling programs to send less wate to the landfill. By moving toward sustainability, they are reducing their environmental impact, safeguarding their employees, and complying with environmental regulations.

Finding the balance – performance and sustainability

But while sustainability is about the future of our planet, for many PCB fabricators, they must balance sustainability and long-term business success. Therefore, it’s important that PCB fabricators have the production tools and methods that are not only green, but also perform effectively and consistently.

Fortunately, when it comes to PCB cleaning, there are a number of sustainable vapour degreasing cleaning fluids that are not only safe for workers and the planet but also clean exceptionally well. These new cleaning fluids not only comply with strict new environmental regulations but are lab-tested and analysed to ensure the cleaning results are reliable, consistent, and just as good, if not better, than the older cleaning fluids.  They help PCB manufacturers operate in the most efficient, environmentally sound ways while still producing high-quality boards and keeping their company successful. All while meeting evolving regulatory requirements. 

Get help meeting the sustainability challenge

With any cleaning method, the goal is to produce clean PCBs at the lowest possible cost to maintain profitability and overall business success. However, sustainability also needs to play a role. PCB fabricators must not only meet customer expectations and production requirements but must also be ethically and environmentally responsible. The goal is to minimise water pollution, control emissions, limit waste disposal and be as safe for exposed workers as possible.  Sustainable PCB fabricating, when done right, can also improve a company’s reputation and attract more clients and better employees.

For PCB fabricators looking for help in selecting and using sustainable PCB cleaning fluids, it is essential to work with a partner with sustainable cleaning fluid and vapor degreasing expertise. Based on the specific PCB components and layouts, and the contaminants encountered, they can recommend sustainable fluids and cleaning methods that will not only meet their PCB cleaning needs today, but that will also comply with emerging, long-term local, national, and global environmental regulations well into the future.