Studies On Preparation And Properties Of PTFE/SiO₂/Glass Fiber Composite Substrates

As ideal microwave dielectric composite materials,the microwave composite substrate has been widely used in communication,military,aerospace and other fields.Polytetrafluoroethylene-based composite substrates have been used more and more widely because of its stable dielectric properties and low dielectric loss.With the advent of the 5G era,from food and clothing to aerospace,changes will occur in all fields.Signal transmission will also develop in the direction of high speed,low latency,low power consumption and interconnection.Researchers from various countries have developed a series of microwave composite substrates by using polytetrafluoroethylene as the base material and applying different reinforcing materials.The research of high-performance PTFE/SiO₂/GFM composite substrate material has important scientific significance.In this paper,PTFE is used as matrix,glass fiber mat?GFM?and SiO₂ as reinforcing materials to prepare composite substrate with specific properties and coupling agent and thickener are studied.The main research contents are as follows:1.The effects of preparation technology on the dielectric properties and water absorption of composite substrates were systematically explored.The effects of natural air-drying or oven-drying,vertical or horizontal drying,and the method of dipping or scraping on layers and the amount of glue were compared.The composite substrate is prepared for testing and analysis,so as to determine the optimal layers preparation process.The results show that the method of rapidly oven-drying can simulate a production line,and the amount of the glue on layers is significantly improved.The operation of drying the layers in the vertical direction can obtain a lower dielectric loss and a higher dielectric constant.Under the method of dipping+vertical+oven-drying,the dielectric constant of the substrate prepared at 10 GHz is 2.52,the dielectric loss is 0.003,and the water absorption is 0.024%.Based on the analysis of various data,it is concluded that the performance of the composite substrate using this method is the best excellent in the groups.2.Five different coupling agent formulations were used to make composite substrates.The coupling agent formulation was used as the only variable in the same experiment,and the effect of different coupling agents on the performance of the composite substrate were studied.Two groups of Z6124 and KH550+Z6124 substrates with similar performance were selected,and the effect of different coupling agent concentrations on the performance of the composite substrate was studied to determine the optimal coupling agent formula and concentration.At the same time,the micro-waveform appearance analysis,dielectric performance and water absorption of the substrate were tested.The results show that when the content is 0.3 wt.%HK550+1.2wt.%Z6124,the performance of the substrate is optimal,the dielectric performance is improved,and the dielectric constant and loss are medium 2.65 and 0.0022.3.The effect of different coupling agents on slowing down the settlement of ceramics in solutions was studied,and it was found that when polyacrylic acid was used as a thickener,the effect is obvious.The research on composite substrates prepared with different concentrations of polyacrylic acid found that the performance of substrate was the best when polyacrylic acid was added at 1 wt.%.And its water absorption is 0.012%,dielectric constant is 2.71,and dielectric loss is 0.0015.The effect of adding different contents of Al₂O₃ and SiO₂ on the performance of the composite substrate was studied.It was found that as the doping amount increased,the content of the ceramic filler inside the substrate increased,which increased the dielectric constant of the substrate.When the dopping content of Al₂O₃ and SiO₂ is 130 wt.%,The dielectric constant of the substrate reaches 3.5,the dielectric loss is 0.0027,and the water absorption is 0.02%.