聚苯乙烯/六方氮化硼微波复合基板的制备与性能研究

Investigation on Preparation and Properties of Polystyrene/Hexagonal Boron Nitride Microwave Composite Substrates

针对高功率器件、高密度封装等微波通信领域对高性能微波复合基板的迫切需求,该文提出了一种将双螺杆造粒和热压成型结合的新技术,制备了以高抗冲聚苯乙烯(HIPS)为基体、六方氮化硼(h-BN)陶瓷为填料的高导热微波复合基板,并对基板的显微结构、热学性能和介电性能进行了全面表征。结果表明,采用大粒径(25μm)的h-BN(h-BN_(25))比小粒径(5μm)的h-BN(h-BN_(5))填充后更有利于提高复合基板的热导率(λ),降低其介电损耗(tanδ)。随着h-BN_(25)质量分数(w(h-BN_(25)))从0增加至70%,HIPS/h-BN_(25)微波复合基板的λ从0.13 W·m^(-1)·K^(-1)提高到7.43 W·m^(-1)·K^(-1)(面内)和2.55 W·m^(-1)·K^(-1)(面间),分别是纯HIPS的57倍和20倍,表明采用以上制备技术能实现h-BN在HIPS基体中的定向排列,构建有效的面内导热网络。同时复合基板的tanδ由7.3×10^(-4)降低至5.3×10^(-4)(10 GHz下),热膨胀系数α从93.8×10^(-6)/K降至18.7×10^(-6)/K。填充w(h-BN_(25))=70%的HIPS/h-BN 25微波复合基板综合性能优异,10 GHz时,其介电常数ε_(r)=3.9,tanδ=5.3×10^(-4),λ=7.43 W·m^(-1)·K^(-1),α=18.7×10^(-6)/K,在微波通信领域具有良好的应用前景。

In response to the urgent demand for high performance microwave composite substrates for high power devices,high density packaging and other microwave communication fields,a new technique combining twin-screw pelletizing and hot press molding is proposed to prepare high thermal conductivity microwave composite substrates with high anti-impact polystyrene(HIPS)as the matrix and hexagonal boron nitride(h-BN)ceramics as the filler.The microstructure,microwave dielectric properties and thermal properties of the substrates are fully characterized.The results show that the use of h-BN_(25) with a large particle size of 25μm is more beneficial than h-BN_(5) with a small particle size of 5μm in improving the thermal conductivity λ and reducing the dielectric loss tanδ.As the filling ratio w of h-BN_(25) increases from 0 to 70%,the thermal conductivity of the HIPS/h-BN_(25) microwave composite substrate increases from 0.13 W·m^(-1)·K^(-1) to 7.43 W·m^(-1)·K^(-1)(in-plane)and 2.55 W·m^(-1)·K^(-1)(inter-plane),which are 57 and 20 times higher than that of-pure HIPS,respectively,indicating that the above-mentioned preparation technique can realize the directional arrangement of h-BN in the HIPS matrix and build an effective in-plane thermal conductivity network.Meanwhile,the dielectric loss tanδof the composite substrate is reduced from 7.3×10^(-4) to 5.3×10^(-4)(10 GHz),the coefficient of thermal expansionαis reduced from 93.8×10^(-6)/K to 18.7×10^(-6)/K.The HIPS/h-BN_(25) microwave composite substrate filled with 70% of h-BN_(25) ceramic has excellent comprehensive performance,the thermal conductivity λ=7.43 W·m^(-1)·K^(-1),dielectric constant ε_(r)=3.9,dielectric loss tanδ=5.3×10^(-4) and the coefficient of thermal expansionα=18.7×10^(-6)/K at 10 GHz,which exhibits good application prospects in the field of microwave communication.