Studies On The Preparation And Properties Of PTFE/SiO₂ Microwave Composite Dielectric Substrate

In recent years,with the rapid development of electronics industry and modern communication industry,there has a strong demand of high-frequency microwave substrates.However,it also put forward higher performance requirements of the highfrequency microwave substrate.The ceramics and glass fiber reinforced PTFE-based composites developed by Rogers have been favored by users because of excellent performance.Due to the lack of domestic products,the microwave substrate material dominantly depended on foreign importation and it is practical significance to develop usable microwave substrates.In this paper,the PTFE is used as the matrix and the inorganic powder as the filler with the E-glass doping,and the effect of silica and E-glass modified with different methods and different silane coupling with agent on the microwave dielectric substrate properties have been studied.In this paper,the single variable principle has been used to study the substrate performance with the Coupling agent F8261 and KH550 hydrolyzed at different temperatures and p H,then the optimum hydrolysis temperature and pH are determined.Under the previous results,the coupling agent F8261,KH550,Z6124 were compounded two by two,and the optimum ratio was studied respectively.Finally,the effects of different coupling agent modified E-glass on the properties of substrates were studied.The main contents of the study are as follows:1?Hydrolysis conditions of coupling agents?F8261 and KH550?: Through the single variable principle,the optimum hydrolysis temperature of the F8261 and KH550 were confirmed with 50?,and the most suitable PH value of F8261 were 4,and KH550 were 11 respectively.We could see that the coupling agent F8261 make the microwave dielectric substrate less dielectric loss and smaller water absorption medium substrate by comparison of the two coupling agent modification.However,the coupling agent KH550 modification made the microwave dielectric of substrate denser,and have greater the dielectric constant.Nevertheless,the disadvantages of the KH550 modification was the bigger dielectric loss and deterioration of the absorption rate.2?Compound coupling agent modification: The coupling agent Z6124 and KH55 were compounded according to the different proportions,and the optimal couplingagent amount was 1.2 wt.% Z6124+0.3 wt.% KH550.The optimal coupling agent amount of F8261 and KH550 were 1.2 wt.% F8261+0.3 wt.% KH550.The reason was that the synergies effect has achieved the best with the ratio and reach the balance of hydrophilic-lipophilic,so the adhesion of silica and PTFE interface has been greatly improved,which made the sample more compact.3?The modification of glass fiber: E-glass with different coupling agent modified was added to PTFE / SiO₂ microwave composite substrate system,and then the impact on the performance of microwave composite substrate was studied,as well as the differences of the several kinds of modification methods were compared.The conclusion is as follows: the coupling agent Z6124 promoted the compactness of the sample,and the substrate had better dielectric properties;the coupling agents KH550 were hydrophilic oleophobic,so the substrate has bigger water absorption;the substrate modified with coupling agent F8261 has a smaller dielectric loss.The substrate using KH550 and Z6124 compound coupling agent had beeter performance of dielectric constant,dielectric constant temperature coefficient,density and water absorption than the substrate modified with F8261 and KH550 compound,except the dielectric loss.