What Does Halogen-Free Mean?
What Does Halogen-Free Mean?
In regards to “Halogen Content”, we are specifically talking about Chlorine, Fluorine, Bromine, Iodine and Astatine elements which have been commonly used in the production of electronics and plastics such as PVC and Teflon. During manufacturing processes, halogens have often been added to components to make them withstand high temperatures and to be flame-retardant, but they are salt-forming compounds which are highly reactive and have low melting points:
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•Chlorine: Commonly used as a bleach and disinfectant for cleaning pools, it is also used in electronic components and can cause serious problems if ignited, creating a poisonous gas.
•Fluorine: Like chlorine is a gas, but it is more reactive and used in refrigerants, aerosol sprays and rocket fuels (as well as toothpaste).
•Iodine: This solid is added to halogen lamps to extend the life of a filament.
•Bromine: This fluid is used for flame-proofing, pesticides and dyes.
•Astatines: Another solid and somewhat like Iodine, this material has no practical uses right now since it highly unstable and radioactive.
Consumers may not realize it, but many electronics are burned at the end of their life, thus potentially releasing all sorts of dangerous toxins. While none of these halogens used in electronic devices directly harm humans or the environment, they can definitely be harmful if a fire is involved or when proper recycling and disposal is not used, such as in developing countries.
Have we scared you yet? Doesn’t it make sense to avoid these compounds? This is exactly why the “Halogen-Free” efforts were initiated. This is not a government mandated process but a demand by environmentally-conscious consumers and groups to remove or at least reduce toxic materials from manufacturing processes where items like wires and cables, printed circuit boards, films, connectors, mechanical plastic parts and other items are made.
To be classified as “halogen-free, a substance must consist of less than 900 parts per million (ppm) of chlorine or bromine and also have less than 1500 ppm of total halogens, according to the International Electrochemical Commission, Restriction Use of Halogen (IEC 61249-2-21) which involves printed circuit boards and interconnecting structures.
The reason EIM pays such special attention of all these “Green” efforts is because barcode labels are very much used to identify plastic and electronic products and therefore the ingredients in our labels and inks are just as accountable. We take this very seriously and offer a range of thermal transfer ribbons, for instance, that are not only better for the environment, but they also have lower smoke toxicity if exposed to fire and will reduce damaging corrosion to electronic devices.
Our ribbons classified as “Halogen-Free” include :
•T84H/T85 – High Quality Resin, for high temperatures and chemical exposure
•T80/T81 – General Purpose Resin
•T144/T145 – Premium Wax/ Resin
With competitive price and timely delivery, SUNUA sincerely hope to be your supplier and partner.
•T146/T147 – General Purpose Wax/Resin
•T38/T39 – Economical, General Purpose Wax
To go along with the Halogen-Free movement, we also have a range of high temperature polyimides, polyester and aluminum products to offer. As with all our label materials, we regularly get updates from our suppliers regarding their compliance with RoHS, REACH and Halogen Content and can provide formal Hazardous Material Compliance certifications upon request.
What's driving the need for halogen-free products?
Elemental chlorine and bromine are highly toxic and certainly do not appear in the make-up of electronics, but organobromides are used as flame retardants in PCBs, molding compounds, adhesives, solder masks, cable insulation and flexible circuits, while polyvinyl chloride or PVC is very common as insulation and as a mechanical damping material. The most common use for bromine and chlorine compounds is as a flame retardant, and of course, this is a good thing, to mitigate the effects of burning components causing dangerous fires. It can also be said that in normal use and eventual professional recycling of electronics, bromine and chlorine compounds do not pose a significant hazard - they are only seen as problematic in the illegal and unregulated burning of the electronics, sometimes carried out to recover valuable metals such as copper. At high temperatures, bromine and chlorine compounds can release dioxins which are Persistent Organic Pollutants (POPS) known to be carcinogenic, and furans which are toxic and possibly carcinogenic. The levels of these chemicals released is however mixed with intake from many other sources. For example, the US Environment Protection Agency estimate that more than 90% of dioxins are actually ingested from animal fats [1]. Also, furans appear and are accepted in staples such as roasted coffee and processed baby foods at a low level [2].
There has been increasing concern about ‘halogens’ in electronics - the five or sometimes six, chemically-related group 17 elements in the periodic table. Actually, the focus is on bromine and chlorine – of the other halogens, fluorine is not currently a concern, iodine is not generally used and astatine never is, being a rare radioactive element. The sixth, tennessine, has only been made in the lab and again decays very quickly with largely unknown properties and is not used.
Picture 1: The halogens in the periodic table
Halogen-free is not mandatory
Unlike with the RoHS and REACH directives in Europe and their equivalents round the world, which have banned certain substances by law, there is no statutory requirement to eliminate halogens from electronic equipment. There are however standards which make recommendations, for example, for circuit boards, IEC 61249-2-21 sets compliance limits of 900ppm by weight of PCB material for bromine, 900ppm for chlorine and 1500ppm for the total of the two. If the limits are not exceeded, a supplier can claim ‘halogen-free’ status. Another standard, JS709C, covers electronics more generally and has slightly higher limits for materials other than circuit boards of 1000ppm by weight for bromine from brominated flame retardants (BFRs), and 1,000 ppm of chlorine by weight from chlorinated flame retardants (CFRs), polyvinyl chloride (PVC) congeners and/or PVC block polymers, copolymers or polymer alloys containing PVC. Under these limits, the material can be identified as ‘low halogen’ according to JS709C. Under some circumstances higher levels are permitted in plastics as long as they are not flame retardants, PVC or containing PVC.
Halogen-free may attract a premium but can have performance advantages too
In response to health concerns and with standards setting voluntary limits, some manufacturers of products are anticipating regulation and asking their suppliers for ‘halogen-free’ components including PCBs, plastics and other non-metallic materials. To achieve this and still maintain flammability ratings, alternative materials must be used and for circuit boards for example, phosphorous or nitrogen can be used in the resin as flame retardants. Halogen-free or ‘green’ molding compounds, adhesives, and other materials are also available but require very careful qualification for the electronics applications to ensure that product reliability is maintained under all environmental conditions. Characteristics that must be evaluated include at the minimum: coefficient of thermal expansion (CTE), glass temperature (Tg), moisture absorption, adhesion strength and flexural modulus.
Although in some cases halogen free materials can be more expensive, for example solder paste and circuit boards, other replacement materials such as adhesive can actually be lower cost, but in total there is expected to be a small premium to pay for halogen-free. There are advantages other than environmental however, halogen-free circuit boards can have better dielectric breakdown ratings, lower coefficient of thermal expansion, higher glass melting point, Tg, which enables higher operating temperature and lower moisture absorption rate.
Flex Power Modules is responding
Flex Power Modules has researched the topic of converting products to halogen-free and with appropriate material changes, DC/DC conversion products BMR491 and BMR492 have been shown to achieve compliance to the IEC 61249-2-21 limits. Reliability tests and analysis of field data are ongoing and further products in the range are queued for conversion. Products that are destined for customers that are involved in more commercial type end-uses are prioritized before those for telecom applications, where the application environment is assumed to be relatively inaccessible to persons and eventual disposal of equipment as waste will be tightly controlled. For very cost-sensitive, high-volume applications, customers may still have the opportunity to request a non-halogen-free product. Requests for conversion of a particular product to halogen-free earlier than programed can be considered depending on circumstances, and new products in certain application areas will be developed halogen-free from the outset.
Conversion to halogen-free is a journey, and inevitably more chemicals might be identified for exclusion in the future - antimony for example. Flex Power Modules will stay at the forefront of materials technology to ensure that their customers’ products remain as safe as possible for the environment and its inhabitants.
[1] https://www.epa.gov/dioxin/learn-about-dioxin
[2] Moro, S.; Chipman, J. K.; Wegener, J. W.; Hamberger, C.; Dekant, W.; Mally, A. (2012). "Furan in heat-treated foods: Formation, exposure, toxicity, and aspects of risk assessment" (PDF). Molecular Nutrition & Food Research. 56 (8): 1197–1211.
Contact us to discuss your requirements of halogen free flame retardant materials. Our experienced sales team can help you identify the options that best suit your needs.