If you’ve heard of the term “halogen-free PCB” and want to learn more, you’ve come to the right place. We share the story behind this printed circuit board.

Find out the facts about halogens in PCB, halogens in general and requirements for the term “halogen-free”. We also looked at the advantages of halogen-free.

What is halogen-free PCB?

In order to meet the requirements of a halogen-free PCB, the board must contain no more than a certain amount of halogens in parts per million (PPM).

Halogens in polychlorinated biphenyl

Halogens have a variety of uses in relation to PCBS.

Chlorine is used as a flame retardant or protective coating for polyvinyl chloride (PVC) wires. It is also used as a solvent for semiconductor development or cleaning computer chips.

Bromine can be used as a flame retardant to protect electrical components or to sterilize components.

What level is considered halogen-free?

The International Electrochemistry Commission (IEC) sets the standard at 1,500 PPM for total halogen content by limiting halogen use. The limits for chlorine and bromine are 900 PPM.

PPM limits are the same if you comply with the Hazardous Substance limit (RoHS).

Please note that various halogen standards exist on the market. Since halogen-free production is not a legal requirement, the permissible levels set by independent entities, such as manufacturers, may vary.

Halogen-free board design

At this point, we should note that true halogen-free PCBS are hard to find. There may be small amounts of halogens on the circuit boards, and these compounds can be hidden in unexpected places.

Let’s elaborate on some examples. The green circuit board is not halogen-free unless the green substrate is removed from the solder film.

Epoxy resins that help protect PCBS may contain chlorine. Halogens may also be hidden in ingredients such as glass gels, wetting and curing agents, and resin promoters.

You should also be aware of the potential pitfalls of using halogen-free materials. For example, in the absence of halogens, the solder to flux ratio can be affected, resulting in scratches.

Keep in mind that such problems don’t have to be overcome. An easy way to avoid scratches is to use solder resist (also known as solder resist) to define pads.

It is important to cooperate with well-known PCB manufacturers to ensure transparency of halogen content in PCB. Despite their recognition, not every manufacturer currently has the capacity to produce these boards.

However, now that you know where the halogens are and what they are for, you can specify requirements. You may need to work closely with the manufacturer to determine the best way to avoid unnecessary halogens.

Although obtaining a 100% halogen-free PCB can be a challenge, you can still manufacture a PCB to an acceptable level in accordance with IEC and RoHS regulations.

What are halogens?

Halogens are not themselves chemicals or substances. The term translates from Greek to “salt-making agent” and refers to a series of related elements in the periodic table.

These include chlorine, bromine, iodine, fluorine and A – some of which you may be familiar with. Fun fact: Combine with sodium and halogens to make salt! In addition, each element has unique attributes that are useful to us.

Iodine is a common disinfectant. Fluoride compounds such as fluoride are added to public water supplies to promote dental health, and they are also found in lubricants and refrigerants.

Extremely rare, its nature is poorly understood, and Tennessee Tinge is still being studied.

Chlorine and bromine are found in everything from water disinfectors to pesticides and, of course, PCBS.

Why create halogen-free PCBS?

Although halogens play a vital role in PCB structures, they have a disadvantage that is hard to ignore: toxicity. Yes, these substances are functional flame retardants and fungicides, but they cost a lot.

Chlorine and bromine are the main culprits here. Exposure to any of these chemicals can cause symptoms of discomfort, such as nausea, coughing, skin irritation and blurred vision.

Handling PCBS containing halogens is unlikely to result in dangerous exposure. Still, if the PCB catches fire and emits smoke, you can expect these adverse side effects.

If chlorine happens to mix with hydrocarbons, it produces dioxins, a deadly carcinogen. Unfortunately, due to the limited resources available to safely recycle PCBS, some countries tend to perform poor disposal.

Therefore, improper disposal of PCBS with high chlorine content is dangerous to the ecosystem. Burning these gadgets to eliminate them (which does happen) can release dioxins into the environment.

Benefits of using halogen-free PCBS

Now that you know the facts, why use a halogen-free PCB?

The main advantage is that they are less toxic alternatives to halogen filled alternatives. Prioritizing the safety of you, your technicians, and the people who will be handling the boards is enough to consider using a board.

In addition, the environmental risks are much lower than for equipment that contains large amounts of such hazardous chemicals. Especially in areas where best PCB recycling practices are not available, lower halogen content ensures safer disposal.

In an age of booming technology, where consumers are becoming increasingly aware of toxins in their products, the applications are almost limitless — ideally, halogen-free for the electronics in cars, mobile phones and other devices we keep in close touch with.

But reduced toxicity is not the only advantage: they also have a performance advantage. These PCBS can usually withstand high temperatures, making them ideal for lead-free circuits. Since lead is another compound that most industries try to avoid, you can kill two birds with a rock.

Halogen-free PCB insulation may be cost-effective and effective for disposable electronics. Finally, because these boards transmit a low dielectric constant, it is easier to maintain signal integrity.

All of us should strive to raise awareness to limit avoidable hazards in critical equipment such as PCBS. Although halogen-free PCBS are not yet regulated by law, efforts are being made on behalf of concerned organizations to phase out the use of these harmful compounds.