Preparation And Properties Of Low-Dielectric Constant Epoxy Matrix Composites

As an essential industrial raw material,epoxy resins are widely used in many applications such as coatings,adhesives,and sealants,etc.However,the high curing temperature,and high dielectric constant of epoxy resin limit their application in the fields of the integrated circuits and semiconductors.The purpose of improving these shortcomings of epoxy resins were achieved by designing the structural and introducing the fillers in the composite materials.In this study,the bisphenol A type epoxy resin（E51）system cured at room temperature was prepared by using three different acrylamides.Acrylamides were obtained by reacting acrylic acid（HAA）with three aromatic amines,including 4,4′-Diaminodiphenyl methane（DDM）,2,2-Bis[4-（4-aminophenoxy）phenyl]propane（BAPP）and ,4′-（Hexafluoroisopropylidene）bis（p-phenyleneoxy）dianiline（HFBAPP）.The curing of epoxy resin with three kinds of acrylamides could be easily realized at room temperature.Among them,Among them,HFBAPP-HAA curing agent performs best.The dielectric constant and dielectric loss values for E51/HFBAPP+HAA were 2.99 and 0.017 at 18.3 GHz,respectively.The thermal performance was also the best,with a carbon residue rate of 14.97%at 800℃,flexural strength was 109.4 MPa,9.2%elongation at break.Particle-reinforced low-dielectric composite materials were prepared with hollow glass beads（HGB）as fillers.The results of test confirmed that the thermal and dielectric properties had been effectively improved.However,with the addition of HGB particles,the mechanical properties of composites have decreased.When the addition of HGB was 10 wt%in E51/HFBAPP+HAA system,the T₅、T₁₀ and Y_c reached 341.6 ℃,373.7 ℃ and 24.99%,respectively.The value of dielectric constant and dielectric loss were as low as 2.31 and 0.0131 t 18.3 GHz,flexural strength was 64.1 MPa,6.5%elongation at break.The thermal and dielectric properties of low-dielectric composites have been improved by adding diatomite（CP）particles.When the addition of CP was 10 wt%in E51/HFBAPP+HAA system,the T₅、T₁₀ and Y_C reached 351.4 ℃,376.3 ℃ and 23.72%,respectively.The value of dielectric constant and dielectric loss were as low as 2.76 and 0.0136 at 18.3 GHz.At this time,the elongation at break and tensile strength are 7.1%and 78.1 MPa,respectively.In addition,the tensile strength and flexural strength of composites have decreased with the addition of CP particles from the pure resin.The elongation and impact strength increased first and then decreased.The maximum elongation and impact strengths at break of 10.7%and 45.8 MPa were obtained for the composite having 2.5 wt%CP loading.Simultaneously,the value of dielectric constant and dielectric loss were as low as 2.92 and 0.0155 at 18.3 GHz.