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Halogen-free PCB, how much do you know?

  • 2019-08-13 10:53:26

Within the classification of board, we have a type of pcb circuit board called halogen-free board. So, how much do you know about halogen-free PCB.


What is a halogen-free base material?

According to the JPCA-ES-01-2003 standard: a copper clad laminate having a chlorine (C1) and bromine (Br) content,which respectively less than 0.09% Wt (weight ratio), It is defined as a halogen-free copper clad laminate. (At the same time, the total amount of CI+Br is ≤0.15% [1500PPM])


Why should we ban halogen?

Halogen refers to a halogen element in the periodic table of chemical elements, including fluorine (F), chlorine (CL), bromine (Br), and iodine (1). Currently, flame retardant base materials are mostly brominated epoxy resins. However, research by related institutions has shown that halogen-containing flame  retardant materials will release a lot of unpleasant and high-toxic gases when they are burned on fire. They are cancer-free and cannot be discharged after ingestion. They are not environmentally friendly and affect human health. Therefore, the European Union initiated the ban on PBB and PBDE as flame retardants in electronic information products.


The principle of a halogen-free base material

Most of the halogen-free materials are mainly phosphorus and phosphorus-nitrogen. When the phosphorus-containing resin is burned, it is decomposed by thermal decomposition to form a polyphosphoric acid, which is highly dehydrated, and forms a carbonized film on the surface of the polymer resin. The insulating surface of the insulating resin is in contact with the air to extinguish the fire and achieve a flame retardant effect. A polymer resin containing a phosphorus-nitrogen compound generates a non-combustible gas during combustion to assist the resin system in flame retardancy.


The Characteristics of halogen-free base material

1.Insulation of materials

The substitution of P or N for the halogen atom reduces the polarity of the molecular bond of the epoxy resin to a certain extent, thereby improving the insulation resistance and the puncture resistance of the quality.


2.Water absorption of materials

Since the N and P foxes in nitrogen-phosphorus oxy-resin are less electron-relative to halogen, Halogen-free sheet are less likely to form hydrogen bonds with hydrogen atoms in water than halogen materials. Therefore, their materials have lower water absorption. Conventional halogen-based flame retardant materials. For sheet materials, low water absorption has a certain impact on improving the reliability and stability of the material.


3.Thermal stability of materials

The content of nitrogen and phosphorus in the halogen-free sheet is larger than that of the common halogen-based material, and thus the monomer molecular weight and the Tg value are increased. In the case of heat, the molecular mobility of the molecule will be lower than that of the conventional epoxy resin, and thus the halogen-free material has a relatively small coefficient of thermal expansion.


Conclusion

Halogen-free circuit boards have been able to meet the quality requirements of circuit boards because of their low water absorption and environmental protection requirements. Therefore, the demand for halogen-free circuit boards have become larger and larger. More multilayer pcb prototyping and fabrication services from www.fastturnpcbs.com.



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