Generally, since the name Halogen-free PCB implies that it does not contain halogens, the products do not include any compound obtained from these elements. Most people in the electrical and electronics production defined halogen-free PCB the same way IPC organization (Association that Connects Electronic Industries) defined it in their recent presentation.
Electronic and electrical products are said to be halogen-free if they are compiled without the deliberate use of halogens in the manufacturing process and not found in the raw material used in the production process by companies. And also when halogen elements are not deliberately added in the final product.
Through the designing processes of printed circuit boards, many mixtures and elements are employed for different purposes. At the introduction of PCB development of technology applications, many toxic compounds were used as an aspect of manufacturing cost savings or due to the specific and useful nature of the element.
As humanity develops a greater understanding of the threats that the materials present for life in today's world, manufacturers are changing methods and finding new materials that do not pose a threat to people working with those products.
The basic compounds applied in PCB developments belong to the group of halogen elements. Although halogens present specific advantages for the improvement of electronics, they are toxic to human life in one or two ways.
As there are still questions about the harmfulness of halogens in PCB development, there are two main elements that constitute the general consent of a halogen-free PCB. Each provides a specific benefit for the safety and functionality of electronics in general but represents a threat to the continuity of human life and nature.
Studies by relevant agencies have shown that halogen-containing flame retardant materials (Polymerized Polybrominated Biphenyls PBB: Polymerized Polybrominated Biphenyl Ethers PBDE) will emit dioxin (Dioxin TCDD), Benzfuran, etc. when they are discarded and burned. The smoke is large, the smell is bad, there is a highly toxic gas, it is carcinogenic, and cannot be discharged after ingestion, which seriously affects health.
Therefore, EU law prohibits the use of six substances, including PBB and PBDE. China's Ministry of Information Industry also requires that electronic information products put on the market must not contain substances such as lead, mercury, hexavalent chromium, polymerized polybrominated biphenyls or polymerized polybrominated biphenyl ethers.
It is understood that PBB and PBDE are basically no longer used in the copper-clad laminate industry, and bromine flame retardant materials other than PBB and PBDE are used more frequently, whose chemical formula is CISHIZOBr4. Although this type of copper-clad copper-containing copper-clad laminates is not regulated by any laws and regulations, this type of copper-clad copper-containing copper-clad laminates will release a large amount of toxic gas (brominated type) and emit smoke when burning or Large electrical fire; when PCB is used for hot air leveling and component welding, the plate is affected by high temperature (> 200ºC), and it will also release a small amount of hydrogen bromide; it is still being evaluated whether toxic gas will also be released. On an exposure of halogen free PCB to contaminants it is measured in the form of ppm which is the measurement of contaminate per unit volume of water.
At present, most of the halogen-free materials are mainly phosphorus-based and phosphorus-nitrogen-based. When the phosphorus-containing resin is burned, it is thermally decomposed to form a polyphosphoric acid, which has strong dehydration properties. It forms a carbonized film on the surface of the polymer resin, isolates the resin's burning surface from contact with air, and extinguishes the fire to achieve a flame retardant effect. Polymer resins containing phosphorus-nitrogen compounds generate non-combustible gases during combustion, assisting the resin system with flame retardance.
The qualities of halogen-free printed circuit boards that attract the attention of companies that assemble it are as good or better than comparable halogenated joints. When comparing the datasheets of multiple suppliers of PCB raw materials, it is apparent to recognize that halogen-free printed circuit boards generally have lower CTE. They have a higher Td temperature and longer T-260 and T-288 times. All this means that the printed circuit board will be more suitable for multiple reflux processes and will be able to withstand higher reflux temperatures in PCBA.
Because P or N is used to replace the halogens, the polarity of the molecular bond segment of the epoxy resin is reduced to a certain extent, thereby improving the quality of insulation resistance and breakdown resistance.
Halogen-free PCB because the N and P foxes in the nitrogen-phosphorus redox resin have fewer electrons than halogens like chlorine and bromine, the probability of forming hydrogen bonds with hydrogen atoms in water is lower than that of halogen materials, so the water absorption of their materials is lower than Conventional halogen-based flame retardant materials. For plates, low water absorption has a certain effect on improving the reliability and stability of the material.
The content of nitrogen and phosphorus in the halogen-free sheet is greater than that of ordinary halogen-based materials, so the monomer molecular weight and Tg value have increased. Under the condition of heat, its molecular mobility will be lower than that of conventional epoxy resin, so the coefficient of thermal expansion of halogen-free materials is relatively small.
Due to its low water absorption and environmental protection requirements, halogen-free PCB boards can also meet the quality requirements of PCB boards in other properties. Therefore, the demand for halogen-free PCB boards has been increasing.
There is an increasing demand for environmentally pleasant printed circuit board electronic commodities. Halogenated compounds have been picked for reduction and consequent elimination from the world of electronics PCB. As such, PCBs that are free of halogens are increasingly popular because they are made of a material that does not contain halogens like chlorine and bromine. In addition, the dielectric constant, dissipation factor and damp diffusivity of PCB materials that are described as halogen-free PCBs are distinct from those used in the PCB electronics industry. In terms of manufacturing and marketing, halogen-free material is the best to use and sells quick.
In the European Union, the United States, Japan, and other countries, they have enacted various laws or directives restricting or banning the use of halogen flame retardants. Material manufacturers are also investing in manpower and technology to develop alternatives to halogen flame retardants. Flame retardants commonly used today include phosphorus, nitrogen and some inorganic compounds. And then what is halogen free PCB that we hear so much about now. Here are some of our common halogen free PCB material:
1. When receiving an inquiry about halogen free requirements from the customer, the relevant department shall be notified to conduct a prenatal evaluation to confirm whether the customer's requirements can be met
4. Procurement control: the purchasing department is required to note all halogen-free materials when placing orders, and the products must meet the halogen free PCB legislation. Meanwhile, the supplier is required to provide RoHS and halogen-free SGS test report and MSDS composition list
5. Material input control: all halogen free PCB material sent by suppliers must be labeled with halogen-free label, confirming supplier's COC, and every batch of raw materials must be tested for halogen-free environmental protection
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