The Environmental Advantages And Processes of Halogen-free PCB Manufacturing
First, environmental protection advantage
Reducing toxic substance emissions: Halogen-free PCBS avoid the use of materials containing halogens (such as chlorine and bromine) during the manufacturing process, thereby eliminating the highly toxic gases (such as dioxins) that may be released when halogen-containing materials are burned or incinerated, significantly reducing the harm to the environment and human health.
Reducing wastewater and waste gas pollution: During the production process, the use of halogenated chemical agents is reduced, directly lowering the emission of harmful substances and reducing the pollution level of wastewater and waste gas, which meets modern environmental protection requirements.
Enhancing the safety of resource reuse: Halogen-free PCBS are safer during the recycling process and do not produce harmful substances, which is conducive to resource reuse and in line with the concept of sustainable development.
Comply with international environmental protection regulations: Halogen-free PCBS meet the requirements of EU regulations such as RoHS (Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment) and WEEE (Waste Electrical and Electronic Equipment Directive), which helps enterprises enhance their environmental protection image and smoothly enter the international market.
Second, manufacturing process
Lamination process
Parameter control: The lamination parameters of halogen-free plates need to be precisely controlled. For instance, for Shengyi substrate and multi-layer boards made of PP, a lower sheet material heating rate (1.0-1.5℃/min) and multi-stage pressure combination should be adopted to ensure that the resin flows fully and has good adhesion.
High-temperature maintenance: During the high-temperature stage (above 180℃), it needs to be maintained for a relatively long time (usually 50 minutes) to ensure the adhesion between the copper foil and the substrate, and to prevent delamination or bubble formation after thermal shock.
Drilling process
Parameter adjustment: Halogen-free copper clad laminate materials have relatively high rigidity, and parameters need to be adjusted during drilling. For example, increase the rotational speed by 5-10% and reduce the tool entry and exit speed by 10-15% to obtain a smoother hole wall.
Slag removal treatment: In the horizontal slag removal process, it is necessary to appropriately extend the expansion reaction time, increase the roughness of the hole wall, and improve the adhesion between the electroplated copper and the hole wall.
Etching process
Alkali resistance control: The alkali resistance of halogen-free plates is poorer than that of ordinary FR-4. Extra care should be taken during the etching process and the rework process after solder mask welding. The soaking time in the alkaline stripping solution should not be too long to avoid the appearance of white spots on the substrate.
First board test: When reworking halogen-free solder mask boards, it is recommended to conduct the first board test first, find the optimal parameters, and then carry out batch rework.
Selection of solder mask ink
Halogen-free solder mask ink: There are various halogen-free solder mask inks available on the market. Their performance is similar to that of ordinary liquid photosensitive inks, and the operation methods are similar, but they have a lower water absorption rate and higher environmental protection performance.
Material selection:
Environmentally friendly base materials: Halogen-free PCBS mainly use phosphorus or nitrogen compounds as flame retardants, such as red phosphorus, anhydrous aluminum phosphate, phosphate, etc. These materials are relatively environmentally friendly and do not generate harmful substances.
High Tg value: The nitrogen and phosphorus content of halogen-free plates increases, the molecular weight of monomers rises, the glass transition temperature (Tg value) increases, the coefficient of thermal expansion decreases, and the thermal stability is better.
Third, performance improvement
Electrical insulation: Halogen-free PCBS use P or N to replace halogen atoms, reducing the polarity of the molecular bond segments of epoxy resin, and enhancing insulation resistance and puncture resistance.
Thermal stability: When the nitrogen and phosphorus content in halogen-free plates increases, the molecular motion ability decreases when heated, the coefficient of thermal expansion reduces, and the thermal stability is better.
Water absorption: The probability of nitrogen-phosphorus resins forming hydrogen bonds with water is low, and the water absorption of the material is lower than that of conventional halogen-containing materials, which improves the reliability and stability of the material.
Signal integrity: The dielectric constant of halogen-free PCBS is relatively low, which helps maintain signal integrity, reduce signal distortion and delay, and is suitable for high-speed data transmission.
Fourth, application fields
In the field of communication: It is widely used in base station equipment, communication switches, etc., to ensure the integrity of signals during high-speed data transmission.
In the field of mobile devices: It meets the requirements of smart phones, tablet computers and other devices for thinness, lightness and high performance, and can adapt to the high temperature generated by long-term use.
In the field of automotive electronics, it has been widely applied in power control systems, safety control systems, and infotainment systems, ensuring the stable operation and rapid response of automotive electronic systems.
In the field of medical equipment: Meeting the requirements of high precision and high reliability, reducing the use of halogen-containing chemical agents, and enhancing safety.
