Comprehensive Introduction to Halogen-Free PCB
As electronic products become more widely used, they cater to a diverse range of users, from infants to the elderly. These demographic groups are often more vulnerable compared to teenagers, and even minor threats can pose health risks. Consequently, there is a growing focus on the safety of materials used in electronic products. One crucial step in this direction is the adoption of halogen-free PCB. This choice is rooted in the fact that these materials are free from halogen compounds, rendering them environmentally friendly. Furthermore, halogen-free PCB board do not emit harmful gases under extreme conditions, making them suitable for users of all age groups.
What is a Halogen-Free PCB Board?
Halogen elements, including chlorine (Cl), bromine (Br), and fluorine (F), are members of the 17th group of the chemical periodic table. These elements are commonly used to manufacture flame retardant materials, aiming to enhance the fire resistance of electronic products. However, in certain situations, especially during the disposal of electronic products, halogen elements may be released into the environment, posing potential threats to ecosystems. Moreover, when electronic products burn, substances like polybrominated diphenyl ethers (PBDE) and polybrominated biphenyls (PBB) can release toxic compounds, including polycyclic aromatic hydrocarbons and dioxins, in the emitted black smoke, which can endanger human health. Due to these harmful emissions, the European Union and China have banned the use of PBDE and PBB in electronic products.
In an effort to reduce the use of halogen elements and mitigate the environmental pollution risks, people have started to adopt halogen-free PCB. Halogen-free PCB do not contain halogen elements. According to IEC standards, the chlorine and bromine content in halogen-free copper-clad laminates must not exceed 900 ppm individually, with a total content not exceeding 1500 ppm. These circuit boards typically employ alternative flame retardant materials such as phosphorus and nitrogen to ensure an adequate level of fire resistance. This means that halogen-free PCB not only meet the performance requirements of electronic products but also reduce the adverse impact of halogen elements on the environment and human health.
Advantages of Halogen-Free PCB
In addition to being environmentally friendly, the use of phosphorous and nitrogen as replacements for halogens in Halogen-Free PCBs offers several performance advantages. Here, FS Technology will discuss these aspects.
When increasing the halogen content in substrate materials, it can introduce polar chemical bonds, resulting in higher dielectric constant and dielectric loss. Halogen-Free PCB materials are more polar, which can significantly improve electrical performance and reduce dielectric loss. This makes them particularly suitable for high-speed data transmission applications because they can reduce signal distortion.
Another advantage of Halogen-Free PCB is in terms of thermal stability and moisture absorption. Phosphorous and nitrogen are large molecular elements, which means they exhibit lower molecular mobility when heated, helping to mitigate thermal expansion and contraction. Additionally, they can reduce the likelihood of chemical bonds in composite epoxy resins forming hydrogen bonds with hydrogen atoms in water. These advantages are crucial for enhancing the reliability of circuit boards because they help ensure that PCB remain operational in extreme environments.
Furthermore, Halogen-Free PCB exhibit excellent physical properties such as tensile and flexural strength. These properties are highly useful during CNC machining, ensuring that cutting and drilling operations on the PCB surface can proceed more smoothly, resulting in clean and smooth hole walls.
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