Study On The Surface Modification Technology Of Short Glass Fiber For High Frequency CCL

Polytetrafluoroethylene(PTFE)has been widely used in high-speed high-frequency circuit board substrate because of its good highfrequency dielectric properties,corrosion resistance and wide usage temperature range.However,the main drawback of PTFE is the low mechanical strength and high thermal expansion coefficient.In order to improve these shortcomings of PTFE,glass fiber was used to enhance PTFE matrix,and to fabricate microwave composites.In order to enhance the interfacial combination of glass fiber and PTFE,this study proposes a scheme of modified glass fiber with silane coupling agent containing N-H bond and C-F bond according to the theory of interfacial interaction of composite materials.First of all,the sintering system of glass fiber reinforced PTFE composites was investigated and established.After that,the surface modified glass fiber was obtained by controlling the concentration of the coupling agent,the reaction temperature,and the reaction time.Tensile strength test of composites was employed to evaluate the interfacial connection of composites and to determine the optimum modification process of each coupling agent.The interfacial interaction mechanism of different coupling agents modified glass fiber and PTFE,and the properties of series of modified glass fiber reinforced PTFE composites were investigated.It was found that the incorporate of Z6032 that containing N-H bond and fluorosilane have greatly improved the properties of composites,such as mechanical properties,water absorption,thermal expansion and dielectric properties.In order to replace the expensive fluorine-containing coupling agent,a two-step compound fluorine-containing grafting method was designed,that is,glass fibers were first modified with unsaturated ?-methacryloxy propyltrimethoxy silane(?-MPS),after which they were reacted with 2,2,2-trifluoroethyl methacrylate(TFEMA)to complete the fluoride-functionalization.The results show that performance of the composite using two-step fluoride grafting method is even better the performance of composite using fluorosilane.