The PCB industry is a vast one that entails different forms of circuit boards. The fabrication of PCB requires the use of environmentally-friendly material. Some materials cause hazards to the environment. Hence, the use of safe materials for fabricating circuit boards is advised.
Halogen PCB has become so popular in the electronic industry. This circuit board plays a crucial role in the production of some electronic devices. These boards are unique in terms of their features and advantages. This article seeks to discuss vital information about halogen free PCB. You will get to know about its features, importance, and other things.
Halogen Free PCB – What is it?
From its name, one can easily depict what Halogen free PCB means. When we say something is halogen free, it means it has no halogen. Therefore, halogen free PCB is a circuit that features no halogen components. Halogen components include iodine, bromine, astatine, and fluorine. These components are not environmentally-friendly.
Halogen free circuit boards are safe for producing some electronic devices. Therefore it is important to retain < 900 parts for each million of bromine or chlorine. Halogen itself has several benefits for the flame retardant period. However, it is not environmentally-friendly.
PCB manufacturers design halogen free PCB using a halogen free copper clad. Halogen was banned in PCB because of the health issues associated with it. For instance, exposure to bromine or chlorine is deadly. When chlorine-based elements mix with hydrocarbons, this can cause dioxin. Dioxin is deadly for us.
Halogen flame retardant equipment can be toxic to us as it produces harmful gas. As a result of this, the RoHS forbid the use of halogens in circuit boards. Halogen served as flame retardants in PCBs. However, it was banned in any electronic device. This is because it is crucial to save our environment.
Therefore, halogen free PCB features a copper-clad laminate with <0.09% Wt of bromine and chlorine. Now, halogen free boards incorporate phosphorous-nitrogen and phosphorus. When you burn resin, it decomposes by thermal decomposition. This results in a polyphosphoric acid that forms a carbonized film on the polymer resin. However, the surface of the insulating resin achieves a flame retardant impact when it is in contact with the air.
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How does Halogen Free PCB Work?
Halogen free PCBs have become so popular in the electronics industry. This PCB has great thermal and mechanical properties. Therefore, it is important to understand how this PCB functions.
Water absorption
The ability of halogen free circuits to absorb water is less than a conventional board. Therefore, the nitrogen-phosphorus resin features low electrons of nitrogen and phosphorus. So, the possibility of hydrogen bonding with hydrogen atoms is less than that of Halogen.
Higher moisture absorption can trigger adverse impacts on the electronics. Hence, it can result in conductive anodic filament and popcorning.
Thermal stability
Halogen free PCB features phosphorus and nitrogen. These elements are higher on this board than that of a typical board. Therefore, the value and molecular weight increase.
The molecular mobility of halogen free boards is less than that of the normal board. Therefore, halogen free circuit boards feature a lower CTE.
Insulation
Rather than using halogen, this PCB features nitrogen and phosphorus. These elements improve the break-down voltage and insulation resistance. In halogen free boards, the polarity of the molecular bond of the resin decreases.
Why Halogen Isn’t Safe in PCBs
The use of chlorine and bromine in PCB manufacturing has negative impacts. However, these elements were sometimes used in PCB manufacturing due to their functions. For example, chlorine serves as a flame-retardant. Also, it protects electronic components and serves as polyvinyl chloride clad for wires. Bromine, on the other hand, is a sterilizing agent. It also functions as a flame retardant in components.
It is very important to use safe elements to produce electronic devices. Most of these devices are used in our daily lives. Electronics that contain halogen are not safe for use. This element poses a big threat to lives. The RoHS directive has restricted several brominated compounds. Therefore, the presence of halogen in a PCB might not have a direct effect. The effect of this element takes place after the disposal of various electronics.
The destruction and incineration of these components are what threaten the environment. Therefore, the harm from improper disposal of halogen electronics is what threatens the environment. Halogen free PCB will help protect the environment and lives. Halogen is not a material used in fabricating PCBs. It simply refers to a category of elemental gases.
Despite the functions these elements serve, it is possible to avoid them in PCBs. Exposure to any of these elements can cause a lot of health issues. Therefore, it is crucial to avoid PCBs featuring a good amount of bromine and chlorine. This is a major reason halogen free PCB is popular in the electronics industry. Hence, these PCBs are very ideal for use in most applications.
What is Halogen Free FR4 PCB?
FR4 is the commonest material grade for PCB fabrication. FR means flame retardant. The 4 means epoxy resin reinforced with woven glass. A halogen free FR4 PCB incorporates FR4 rather than halogen. FR4 is a safe material for PCBs.
Halogen free FR4 PCB features an FR4 material at the bottom and top copper layers. FR4 is a good standard for halogen free boards. The major applications of halogen free FR4 PCB are mobile devices and telecommunications. Furthermore, engineers use halogen free FR4 PCBs in applications where smoke is a major concern. This means in designing electronics, halogen free FR4 is a go-to material.
Also, these boards offer great performance in soldering. The properties of halogen free FR4 PCBs may vary depending on the laminate type. Electronic products are at risk of catching fire as a result of short circuits. Therefore, electronic devices should have the ability to prevent fire. To achieve this, the PCB industry must adhere to the industry flammability standards. These standards help to ensure safety.
PCBs feature FR4 to reduce risk of fire. This material increases the threshold of fire ignition. Halogen free FR4 PCBs offer better performance than halogenated flame retardants. The out-of-plane CTE of halogen free PCBs is less than that of halogenated PCBs. In PCB assembly, lower out-of-plane CTE guarantees longer PTH reliability. The presence of FR4 in circuit boards prevents fire.
Halogen free FR is available to meet the increasing demands of environmental protection. Manufacturers should carefully choose a flame retardant material. There are two factors to consider when doing this. These factors are the ways of FR interaction in the polymer system and the mechanism of flame retardance.
Advantages of PCB Halogen Free
PCB halogen free offers a lot of advantages. As a result of this, many applications incorporate this board.
- Offers better insulation and is ideal for use in electronics that need insulation
- This board features great high-frequency performance. Hence, it is a low-cost option for high-frequency applications.
- Halogen free boardshave exceptional mechanical properties. This board is more stable and has better appearance quality.
- It is better incorporated in flame-retardant panels and other products.
- It complies with green regulations. Hence, it is safe for the environment.
- Halogen free PCB features a higher glass melting point (TG). This means that this board can function well at higher temperatures.
- It has a good dielectric constant
- Enhances manufacturing and process of multilayer PCBs.
- Ideal for lead-free circuits. Lead is another toxic element avoided by most industries.
- This board is ideal for multiple reflow processes and will be able to withstand higher reflow temperatures.
The significant advantage of PCB halogen free is that they are safe for the environment.
Importance of Halogen Free PCB Material
The telecommunication and mobile device industries require high speed data transmission. When a signal transmits at high speed on a circuit board, signal integrity becomes a concern. Materials featuring low Df and Dk are ideal for high frequency PCBs.
Halogen free is another requirement for communication boards. For the production of laminates, there are halogen free materials. These materials can be expensive. Thus, halogen free PCB material featuring low DK/Df will meet this demand. Most electronic industries now make use of halogen free materials in electronics.
Halogen free PCB materials don’t have any halogen. They comply with the standards that regulate the amount of halogens in materials. Halogen free PCB materials are present in halogen free PCBs. These materials have low transmission loss. This helps to contribute to the faster transmission of data.
Several PCB manufacturers produce halogen-free materials and prepregs. These materials feature various electrical, physical, and thermal properties. A PCB material without halogen elements like bromine or chlorine is halogen-free.
For several years, manufacturers have used brominated FRs in electronic devices. However, several companies are now promoting halogen free PCBs. Halogen free boards feature higher Td temperatures and T-288 times. This helps to tolerate more reflow cycles and reflow temperatures.
EMC and Panasonic are good examples of halogen free PCB materials. These two materials are ideal for the production of halogen free boards. However, their properties vary. Below are common high free PCB materials available;
- EMC EM-370(D)
- Panasonic R-1566W/R-1551W
- NAN YA NPG-150N
- Panasonic Meg2 (R-1577/R-1570)
- NAN YA NPG-170N
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Applications of Halogen Free PCB
As technology advances, the electronic industry is conscious of toxins in electronic products. PCBs are the core material for the production of most electronic devices. Therefore, halogen free PCBs are ideal for use in most applications. Since these PCBs are environmentally-friendly, it is mostly preferred by manufacturers.
Mobile and Wireless Devices
These devices feature halogen free circuit boards. Mobile and wireless devices are commonly used in our daily lives. The presence of halogen in such devices isn’t safe. Therefore, the use of halogen free boards is common in this application. Mobile device manufacturers now make an effort to produce devices free of halogen.
Automobile Industry
Halogen free PCBs are common in this industry. The automotive industry incorporated halogen free boards in its devices. These boards feature high dielectric and mechanical properties. They are commonly used for insulating structural parts of vehicles.
Telecommunication Industry
Halogen free circuit boards offer high frequency. This makes them ideal for use in applications that require signal integrity. Signal integrity is a major concern in the telecommunication industry. Halogen free PCBs contribute to faster data transmission.
High-end Computing
This is another application that features halogen free PCBs. High-performance computing is a computing system that can solve complicated and demanding problems.
Consumer Electronics
The electronics we have close contact with should be free of halogen. Consumer electronics are appliances we use every day. TVs, radios, and wearables are examples. These devices should never contain halogen. The environmental risk of halogen is much higher when used in these electronics.
Medical Industry
Halogen free PCBs are present in most medical devices. Medical electronic devices like wearables, x-ray, and scanners feature this PCB. Smart health watches and wearable ECG monitors feature this PCB. The use of wearables in the medical industry has increased.
Frequently Asked Questions
Is RoHS PCB halogen free?
No. When a PCB complies with RoHS, it doesn’t mean that it is halogen free. A PCB that is free of halogen must have complied with halogen-specific standards. JS709C and IEC 61249-2-21 are examples of such standards.
Why are halogen free PCBs expensive?
Halogen free circuit boards are more expensive than halogenated boards. The price difference is due to economies of scale. However, PCB manufacturers face a key challenge in the fabrication of this board. Halogen-free materials are more rigid. Therefore, the drilling process suffers from this rigidity.
Conclusion
The electronic industry has continued to promote environmentally friendly electronics. There is a rapid reduction or elimination of halogen elements in PCBs. The PCB industry isn’t also left behind as this industry fabricates more halogen free PCBs. Halogens are toxic elements in the environment.
Halogen comprises chlorine, fluorine, iodine, and bromine. These elements cause a lot of health issues in humans. Therefore, it is important to avoid incorporating them in PCB fabrication. There is an alternative to using halogen as a flame retardant in PCB.
