Aromatic free conformal coatings: What are the options?

5th August 2019
Posted By : Alex Lynn
Aromatic free conformal coatings: What are the options?

Xylene and Toluene. Two words that can evoke concern and add to paperwork for environmental health and safety departments and manufacturing professionals. Aromatic solvents have been safely used for decades by employing basic safety equipment including gloves, masks, and proper workplace ventilation. 

By Dan Griffin

Nevertheless, concerns for maximising employee safety and minimising effects on the environment have led electronics manufacturers to seek out alternatives. For over 20 years, HumiSeal has supplied a wide-ranging group of aromatic-free products across all traditional chemistries to manufacturers for whom these concerns are critical. 

What does aromatic free in conformal coatings mean?

First, a basic explanation of the structure and role of aromatic solvents is in order. The term ‘aromatic’ in this context refers to cyclic hydrocarbons such as toluene, benzene, and xylene where the carbon atom structure is in the form of a closed ring, as opposed to ‘aliphatic’ hydrocarbons such as hexane, where the carbon atoms are in a linear structure. The word aromatic is also used to describe the relatively strong, and not always pleasant, odour associated with compounds of this family.

It is important to understand that in electronics coatings, these solvents, whether aromatic or aliphatic, are not functional parts of the finished coatings but are used only to dissolve and thin the products to allow them to be effectively sprayed or dipped. Since these solvents rarely have an effect on the final product’s performance but are simply evaporated away, it makes sense to choose the least hazardous version available that is adequate for the application method.

What are the problems with aromatic conformal coatings solvents?

There are many and they vary in importance but can be broken down into two main categories:

  1. Health hazards including acute toxicity in large quantities, skin and eye irritation hazards, and acute and chronic risks to organs, such as neurotoxicity, due to inhalation of vapours.
  2. Environmental hazards, including toxicity to fish and wildlife as well as contributing to ozone and smog production.

HumiSeal has experience in the design and manufacture of aromatic-free conformal coatings, using technologies such as:

  1. Non-aromatic, environmentally friendlier solvents (LOS, NS, LOC suffixes).
  2. Silicone-based chemistries that are 100% solids - no solvents.
  3. UV-curable-based chemistries that are 100% solids - no solvents

Although it is relatively simple to take precautions in the use of aromatic solvents, some users may prefer safer alternatives for their employees and the environment. This is not a new issue, and HumiSeal remains committed to the development and maintenance of products across all modern chemistries to provide choice and superior product performance in aromatic-free coatings for the electronics industry.


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