Preparation And Properties Of Benzocyclobutene Functionalized Oxide Phosphorus Materials With Low Dielectric Constant And Flame Retardancy

The requirements for electronic device circuit boards have been becoming increasingly strict with the rapid development of electronic products in the high-frequency 5G stage,and it is developing towards the direction of miniaturization,high integration and fine structure of electronic devices.Copper clad laminate（CCL）is one of the representative basic circuit boards in the field of electronic circuit boards.With the increasing integration and complexity of CCL,substrate materials are required to have good heat resistance,flame retardancy,low dielectric constant（k）,and low thermal expansion coefficient（CTE）to meet their stability,safety,and processability.In this thesis,a series of oxide phosphorous flame retardant materials with low k were designed and prepared by utilizing the advantages of organophosphorus flame retardant materials such as low smoke,low toxicity,high efficiency,and low pollution,as well as the special chemical structure of phenylpropylcyclobutene（BCB）.1.BCB functionalized oxide phosphorus monomers with flame retardancy,which are diphenyl-BCB oxyphosphorus（Ph₂POB）,phenyl-di BCB oxyphosphorus（Ph POB₂）,and tri-BCB oxyphosphorus（POB₃）,were synthesized by introducing the BCB group to the oxide phosphorus compounds.After thermal curing,Ph₂POB,Ph POB₂,and POB₃monomer cured resins were obtained,respectively.Among them,POB₃ monomer cured resin exhibited high thermal stability(T_5%=431 ^oC),low CTE（23.57 ppm/^oC）,and good flame retardancy（THR（Total Heat Release）=30.50 k J/g）.The BCB functionalized spherical silicon nanoparticles（BCBNPs）were doped into BCB functionalized oxide phosphorus monomers,and after thermal curing,Ph₂POB/BCBNPs,Ph POB₂/BCBNPs,and POB₃/BCBNPs composite cured resins were obtained.POB₃/BCBNPs composite cured resin exhibited higher thermal stability(T_5%=443 ^oC),lower CTE（16.71 ppm/^oC）,and better flame retardancy（THR=23.10 k J/g）than those of the corresponding monomer cured resins.Both monomer cured resins and composite cured resins exhibited high elastic modulus and hardness,with the elastic modulus and hardness of POB₃/BCBNPs being 10.03 GPa and 0.83 GPa,respectively.Ph₂POB and Ph POB₂monomer cured resins showed relative low dielectric constants of 2.85 and 2.76,respectively.2.（vinyl）₈-POSS（10 wt%）and DVSBCB prepolymers（p-DVSBCB,10 wt%）were concurrently doped into Ph₂POB,Ph POB₂,POB₃,and POB₃/BCBNPs,respectively.After thermal curing,the BCB functionalized oxide phosphorus composite resins,which are named Ph₂POB/（vinyl）₈-POSS/p-DVSBCB,Ph POB₂/（vinyl）₈-POSS/p-DVSBCB,POB₃/（vinyl）₈-POSS/p-DVSBCB,and POB₃/BCBNPs/（vinyl）₈-POSS/p-DVSBCB,were obtained.POB₃/BCBNPs/（vinyl）₈-POSS/p-DVSBCB composite cured resin exhibited low dielectric constant（2.53）,low CTE（19.94 ppm/^oC）,high thermal stability(T_5%=451 ^oC),high flame retardancy（THR=31.6 k J/g）,and high mechanical properties（elastic modulus and hardness of 22.96 GPa and 1.46 GPa,respectively）.In summary,POB₃/BCBNPs and POB₃/BCBNPs/（vinyl）₈-POSS/p-DVSBCB composite cured resins have relatively low dielectric constant and thermal expansion coefficient,as well as good thermal stability,flame retardancy,and mechanical properties,which are expected to be applied in the field of electronic circuit CCL substrate materials.