Study On Preparation And Performance Of Modified Polyphenylene Ether Resin For High Frequency Copper Clad Laminates

With the development of portable electronic equipment and the information industry,printed circuit boards(PCB)have become the master plate and carrier of electronic products.In addition,due to the advent of the 5G era,PCB,as the core material of communication equipment need to be upgraded and technically innovated as soon as possible,which requires a lower dielectric constant and dielectric loss to adapt to the 5G high-frequency era.Copper Clad Laminates(CCL)as the main PCB substrate with insulation,conduction and support three important functions,which determines the mechanical strength,processing performance,heat resistance,dielectric properties of the PCB,etc,and also the most closely related to the discipline of polymer materials part.CCL is mainly composed of three parts(matrix resin,reinforcing material,copper foil),wherein the performance of CCL is basically determined by the performance of matrix resin.Polyphenylene ether resin(PPO)is one of the five major engineering plastics in the world.With its excellent heat resistance,hydrolytic stability,low moisture absorption,excellent dielectric properties and high glass transition temperature,it has great promise for use in high-frequency CCL.According to the shortcomings,polyphenylene ether is modified by end group grafting to make it a thermosetting resin.Therefore,the main research object of this article is to modify the end group of PPO to graft active functional groups to make them become thermosetting resins,and to study the properties of polyphenylene ethers obtained under different reaction conditions after curing.In this paper,the polyphenylene ether end group are first vinylated using p-chloromethylstyrene(VBC)to make a thermosetting resin,and the modified polyphenylene ether is then cured with the curing agent benzoyl peroxide(BPO).Through Fourier Infrared Spectroscopy(FTIR),it was observed that the ratio of PPO:NaOH was 1:4,PPO:VBC was 1:2.6,and the hydroxyl peak was relatively gentle at the reaction temperature of 60℃,and the double bond of 866 cm-1(-CH-)Vibration peak.The conversion rate of functional groups under different reaction conditions was obtained by using nuclear magnetic resonance H spectroscopy(1H NMR),and the optimal modification conditions were determined.Gel permeation chromatography(GPC)characterizes the structure and molecular weight of modified polyphenylene ether.A small amount of crosslinking of modified polyphenylene ether leads to an increase in molecular weight.Through differential scanning calorimetry(DSC),thermogravimetry(TGA),and dielectric properties analysis,the initial curing temperature(Ti),peak temperature(Tp)and the temperature at the end of the reaction of modified polyphenylene ether are obtained.(Tf)are 188.22℃,207.28℃ and 229.39℃,respectively.According to the thermokinetic equations Kissinger and Crane equations,the activation energy Ea,the frequency factor A and the reaction order are Ea=50.35 kJ/mol,A=4.00×108 min-1,n=0.871,respectively.Using thermal stability analysis,when PPO:VBC is 1:2.8,Td5%is not much different from unmodified polyphenylene ether,so the thermal stability of vinyl polyphenylene ether after curing has little effect.According to the dielectric data,it is judged that the amount of VBC may be insufficient.The presence of sodium phenate increases the dielectric constant and dielectric loss.The dielectric constant is optimally 2.791(1 MHz),and the dielectric loss is basically 0.005(1 MHz)or so.Secondly,end group graft modification of polyphenylene ether and epichlorohydrin(ECH),and then the modified polyphenylene ether is cured with curing agent dicyandiamide(DICY).Through Fourier Infrared Spectroscopy(FTIR),it was observed that PPO:NaOH was 1:4,PPO:ECH was 1:50,and the hydroxyl peak was relatively gentle at the reaction temperature of 65℃,and a 911 cm-1 stretching vibration of the epoxy group was observed.The conversion rate of functional groups under different reaction conditions was obtained by using nuclear magnetic resonance H spectroscopy(1H NMR),and the optimal modification conditions were determined.The structure and molecular weight of modified polyphenylene ether were characterized by gel permeation chromatography(GPC)and the number average molecular weight of the modified epoxy-based polyphenylene ether increased slightly.The curing start temperature(Ti),peak temperature(Tp),reaction end temperature(Tf),activation energy(Ea),and frequency factor(A)of epoxidized polyphenylene ether were obtained through DSC,thermogravimetric and dielectric properties analysis.And the reaction order(n).Td5%of polyphenylene ether increased slightly when PPO:NaOH was 1:5 by thermogravimetric analysis.The optimal dielectric constant of epoxidized polyphenylene ether is 2.354(1 MHz).The dielectric loss is basically around 0.01(1 MHz),and the loss increases slightly,but it still meets the requirements for the use of high-frequency CCL.