Halogen-Free Resin Composition for Low-Loss PCBs

The patent converts the harmful effect of halogenated flame retardants (which produce toxic emissions) into a beneficial halogen-free system that maintains flame retardancy without environmental harm. Specifically, it uses phosphorus-containing compounds and nitrogen-containing compounds that form protective char layers during combustion, converting the potential harm of flame spread into a beneficial protective mechanism that suppresses fire while avoiding toxic emissions.

The patent changes the chemical composition parameters by replacing halogenated compounds with halogen-free alternatives. It specifies using phosphorus-containing compounds (such as phosphates, phosphonates, or phosphinates) and nitrogen-containing compounds (such as melamine or triazine derivatives) to achieve flame retardancy through different chemical mechanisms that do not involve halogen elements, thereby fundamentally changing the material composition to eliminate environmental hazards.

The patent employs a composite flame retardant system combining phosphorus-containing compounds with nitrogen-containing compounds and epoxy resin. This composite approach creates synergistic effects where the phosphorus compound provides flame retardancy through char formation, while the nitrogen-containing compound and epoxy matrix work together to suppress hydrolysis and improve migration resistance. The multi-component system stabilizes the overall composition against degradation.

The patent uses the epoxy resin matrix as an intermediary that protects the phosphorus-containing flame retardant from direct exposure to moisture and hydrolytic degradation. The epoxy network structure acts as a barrier, reducing the interaction between the phosphorus compound and water, thereby maintaining migration resistance while preserving flame retardant functionality.

The patent replaces red phosphorus with phosphorus-containing compounds that are chemically more stable and do not produce phosphine gas under service conditions. The alternative phosphorus compounds (such as phosphates, phosphonates, or phosphinates) are designed to decompose in a controlled manner during fire events, forming protective char layers without generating toxic phosphine emissions, thus eliminating the safety hazard while maintaining flame retardancy.

The patent changes the chemical structure parameters of the phosphorus-based flame retardant from elemental red phosphorus to stable phosphorus-containing compounds with different molecular structures. These compounds have higher thermal stability and lower reactivity toward moisture, preventing phosphine gas formation. The specific chemical parameters (molecular structure, bonding configuration) are modified to eliminate the harmful side reaction while preserving the flame-retardant mechanism.

The patent applies local quality by introducing fluorinated groups at specific locations within the hardener molecule. The fluorinated segments provide hydrophobicity and low dielectric constant properties locally, while other parts of the molecule maintain adhesion functionality. This localized modification allows the hardener to simultaneously achieve good adhesion and excellent dielectric properties by concentrating different functional characteristics in different molecular regions.

The patent changes the chemical composition parameters of the hardener by incorporating fluorinated hydrocarbon chains or aromatic fluorinated groups into the molecular structure. This parameter change (adding fluorine atoms) fundamentally alters the physical and chemical properties: it reduces dielectric constant, decreases hygroscopicity, and maintains or improves adhesion strength, thereby resolving the contradiction between adhesion and dielectric properties.