Study Of Polarization Density On High Frequency And Thermal Conductivity Of Electric Subgrade Plate

With the development of information industry towards high frequency band,traditional printed circuit board can not realize high-speed and low loss signal transmission.The increasing demand for miniaturization and portability of electronic equipment leads to the increase of circuit board packaging density,the narrowing of copper wire spacing,and the further accumulation of heat leading to signal propagation delay and crosstalk.It is of great significance to develop high frequency copper-clad plate with high transmission speed,low transmission loss,high thermal conductivity and high thermal stability.In this paper,dicyclopentadiene phenol epoxy（DCPD-EP）and diamine benzoxazine（DDM-BZ）was used as matrix,dicyclopentadiene phenol phenolic resin（DCPD-PF）as curing agent,and boron trifluoride ethylamine（BF₃-MEA）as an accelerant.The composite substrate with low dielectric and high thermal conductivity was prepared using hydroxylated hexagonal boron nitride（h-BN-OH）and hollow glass beads（HGM）as fillers in the resin system,and the amount of accelerator and the ratio of filler system were studied.The main research contents of this paper are as follows:1)The ratios of DCPD-EP,DDM-BZ,and DCPD-PF were investigated.DDM-BZ was used to copolymerize with DCPD-EP.The introduction of DCPD groups into DDM-BZ increased the free volume of the cross-linked network,reduced the polarization density,enhanced the dielectric properties and improved the thermal stability of DCPD-EP.The addition of DCPD-PF promoted the opening of the oxazine ring and enhanced the complexity of the cross-linked network.The results showed excellent overall performance atω（DCPD-EP）:ω（DDM-BZ）:ω（DCPD-PF）=2:1:1 with a dielectric constant of 4.06 and dielectric loss of 0.014;5%thermal weight loss temperature of 381°C;and thermal conductivity of 0.92 W/（m?K）.2)To study the effect of BF₃-MEA addition on the curing of ternary resin system,the addition of BF₃-MEA can make the epoxy ring and the oxazine ring according to the cationic polymerization reaction mechanism to open the ring to etherification reaction polymerization,increase the heat resistance of the resin system.Experiments show that:when BF₃-MEA is added at 0.8%of the resin,the maximum reaction rate temperature decreases by 30°C,the 5%thermal weight loss temperature increases by 4°C and the bleaching time increases to 451 s.3)Study the effect of filling surface modification h-BN on the performance of copper-clad plates.Hydroxylation improves the dispersion and homogeneity of h-BN in the resin and inhibits the interfacial polarization between itself and the resin.Experiments show that copper-clad plates with h-BN-OH added show a decrease in dielectric constant of 0.48 at 10 GHz,a decrease in dielectric loss of 0.0049 and an increase in thermal conductivity to 0.93 W/（m?K）.4)Study the effect of HGM filling on the performance of copper-clad plates.a hollow positive sphere covered with air,which has the characteristics of low dielectric constant and low thermal conductivity and is added to reduce the dielectric constant and thermal conductivity of copper-clad plates.Experiments have shown that the addition of HGM at 20wt%of the filler system provides excellent overall performance,with a drop in thermal conductivity of 0.4 W/（m?K）,a rise in 5%thermal weight loss temperature of 8°C and a drop in dielectric constant of 0.89,a drop in dielectric loss of 0.0067 at 10 GHz.