Why Use Eco-Friendly Solvents Instead of Aromatic Hydrocarbons for Printed Circuit Boards?_Products News_News | 2-Part Acrylic Adhesive, Structural Acrylics, UV Resin, Cyanoacrylate manufacturer│TEX YEAR Since 1976

Recently, there has been a surge in international environmental awareness, with various manufacturers actively seeking new eco-friendly solvents and green materials for their processes. Among these, the traditional protective coatings for printed circuit boards often contain solvents like toluene and xylene, which are aromatic hydrocarbons. While these solvents boast good solvency and fast drying speeds, they also come with some negative health and environmental impacts.

The popularity of these specific solvents in adhesives and coatings production is due to several key factors:

• Relatively lower cost of solvent materials
• Excellent compatibility with organic polymers
• Slow volatility/drying speed

The last characteristic, slow volatility, is particularly impactful in industrial coating materials, as it minimizes premature drying and skinning of the coating material, which can lead to bubbles and defects.

Whether voluntarily or due to government mandates, you may be considering not using aromatic hydrocarbon solvents in your production process. Our goal is to help you find viable alternatives that not only substitute but also surpass these solvents.

Why Use Toluene in Protective Coatings for Printed Circuit Boards?

Xylene and toluene are two common aromatic hydrocarbon solvents in the adhesive and coatings industry. They have been safely used for decades as long as proper safety measures are in place. These measures include standard PPE: gloves, masks, and adequate workplace ventilation. However, there is a growing movement towards environmental protection and reducing personal health risks, calling for the cessation (or limitation) of these solvents' usage.

Protective coatings must be sprayed onto printed circuit boards and require good flowability to form a uniform film; if the base polymer viscosity is too high, it cannot be sprayed or form a uniform film. The primary function of solvents is to "dilute" the polymer from a thick, pasty consistency to a sprayable and flowable liquid. In fact, solvent thinners for protective coatings are just processing aids and do not affect the final protective film. They evaporate during the drying stage.

Why Use Toluene-Free Protective Coatings for Printed Circuit Boards?

This is primarily related to national and local regulations and restrictions on the use of aromatic solvents. These restrictions are based on some potential health hazards and environmental risks associated with organic solvents, and awareness of these hazards is continuously evolving. All organic solvents have health and environmental considerations, but some regulatory agencies consider additional oversight, control, or elimination of aromatic solvents.

Aromatic hydrocarbons like toluene and xylene pose potential risks in the following areas:

• Personal health and safety
• Environmental hazards: toxicity to fish and wildlife, as well as ozone layer depletion

In terms of personal health and safety, aromatic solvent poses potential risks due to their flammability and toxicity-related issues. While toxicity sounds alarming, and sometimes its risks may be overstated, it is certainly a risk that must be considered. Industrial hygiene can easily be maintained through the use of personal protective equipment and "adequate ventilation."

Any chemical substance (even water!) can potentially be toxic. The key considerations are the route of exposure as well as the concentration and dosage. Nonetheless, some companies opt for strategies without aromatics; in these cases, alternative solvents can be found.

Due to environmental concerns, if mishandled, aromatic solvents may pose risks of air, soil, or water pollution. Air-related risks may include odor and ozone issues. If spilled or improperly disposed of, solvents can certainly pose risks of contaminating soil and water, affecting both human and wildlife.

Alternatives to Aromatic Solvents: Specialty Chemical Solvents, Silicones, and UV Curing

HumiSeal offers three main alternatives for aromatic solvent-based coating materials:

• Non-aromatic solvents
• SR Organic Silicone Protective Coatings
• UV-Curable Protective Coatings

Regarding alternative solvents, HumiSeal has various non-aromatic solutions. In many cases, these alternative thinners offer the same performance effects as standard toluene thinners. If you continue to use solvent-based coating materials, you can opt for these chemical thinners.

The offered product lineup includes:

• Thinner 600
• Thinner 701
• Thinner 905

It's worth noting that each non-aromatic thinner has a specific compatibility list based on the conformal coating used, as outlined in the operating instructions.

Another approach without using aromatics is the use of silicone coatings for printed circuit boards. Coatings suitable for spraying viscosity can be manufactured without using medium solvents. Suitable silicones have a 100% solid content, leaving the entire coating on the printed circuit board without the need for solvents.

Environmentally friendly UV-curable protective coatings are a popular choice for removing processing solvents. Similar to silicones, these coatings provide 100% solids and do not require solvents to adjust viscosity. Unlike solvent-based coating materials, there are no chemical by-products or risks to human and environmental safety when handling these materials.

For further  HumiSeal product  details, feel free to get in touch with us today!  

Resource link: https://blog.humiseal.com/toluene-alternatives-aromatics