Preparation Process And Properties Of PTFE/High Dielectric Constant Ceramic Composite Substrate

With the rapid development of modern communication technology,in order to achieve high miniaturization,integration and high reliability of microwave communication devices,electronic substrate materials are required to have high dielectric constant（ε_r）,low dielectric loss（tanδ）and zero dielectric.The performance of the constant temperature coefficient（τ_ε）.Polytetrafluoroethylene（PTFE）has become a preferred resin material due to its low water absorption,wide dielectric stability,low dielectric loss and strong solvent resistance.Ceramic filled PTFE composites are a research hotspot to improve PTFE.Dielectric properties and thermal stability.In this experiment,polytetrafluoroethylene（PTFE）was selected as the substrate,Na_1/2Nd_1/2TiO₃（NNT）/Li_1/2Nd_1/2TiO₃（LNT）/(Na_xLi_1-x)_0.5Nd_0.5TiO₃（NLNT）ceramics and glass fiber（E-GF）is the main filler,and the preparation and performance of microwave dielectric substrates are studied.In this paper,a single variable method is used to systematically study the composite dielectric substrate.Firstly,three kinds of ceramics,NNT/LNT/NLNT,were prepared by solid phase synthesis.The effect of sintering temperature on ceramic properties was studied.Then,the surface modification of the coupling agent of ceramic powder and the surface hydroxyl treatment of H₂O₂ were studied.Finally,the effects of ceramic and GF filling content and doping ratio on the performance of ceramic/GF/PTFE composite substrates were studied.The main contents are as follows:1.Preparation of ceramic powder:The effects of sintering temperature on the crystal phase,density,dielectric constant,quality factor and dielectric constant frequency coefficient of NNT/LNT/NLNT ceramics were investigated.（a）The optimum sintering temperature for NNT is 1300°C.（b）The optimum sintering temperature of the LNT is 1300°C.（c）When the doping ratio x is adjusted from 0.3 to0.7,the dielectric constant of（NaxLi1-x）0.5Nd0.5TiO3 ceramic can be adjusted within138.1¹44.1,and the dielectric constant frequency coefficient can be 66.5 ppm/°C^Adjusted at 238 ppm/°C.2.Surface modification of ceramic powder:（a）H₂O₂ surface treatment technology was used to increase the number of hydroxyl groups on the surface of the filler powder,which was verified by X-ray photoelectron（XPS）.（b）Surface modification of the filler ceramic powder,using contact angle test,Fourier transform infrared spectroscopy（FTIR）and XPS test to observe the powder modification effect,and finally selected the only coupling agent.Modification scheme:F8261.3.Ceramic/GF/PTFE composite substrate research:（a）NNT/PTFE composite exhibits excellent dielectric loss（≤0.0016）and water absorption（≤0.05%）when the content of NNT ceramic filler is 25 wt.%⁴5 wt.（b）When the LNT ceramic filler content is 25 wt.%⁴5 wt.%,the composite exhibits excellent dielectric loss（≤0.0016）and water absorption（≤0.02%）.（c）When x was increased from 0.3 to 0.7,the effect of(Na_x Li_1-x)_0.5Nd_0.5TiO₃ ceramics on the microstructure and microwave dielectric properties of NLNT/PTFE composites was investigated.When x=0.6,high dielectric constant（ε_r=10.04）,a low dielectric loss（tanδ=0.0026）and a near-zero dielectric constant temperature coefficient（τε=-0.9 ppm/°C）of the microwave dielectric constant composite substrate was obtained.