【作者】 赵强；

【导师】 张怀武；

【作者基本信息】 电子科技大学 ， 电子信息材料与元器件， 2020， 博士

【摘要】 随着电子信息技术向高速、低耗、宽带、集成化发展,一体化低温共烧陶瓷(LTCC:Low Temperature Co-firing Ceramic)系统级封装及无源集成器件成为解决4G/5G手机和基站电子器件的必然选择。如何突破电子材料的截止频率上限,如何解决LTCC生瓷料带工艺中多层磁性铁氧体与电子陶瓷(电感与电容)之间的界面共烧结,成为该领域急需解决的瓶颈技术问题。研发一种新型的LTCC电子材料,使其在同一频率域既可做电感器材料,又可做电容器材料,同时具有比较低的介电损耗和磁损耗,把这样一种LTCC材料称之为复合磁电双性能LTCC材料。这种复合双性能LTCC材料是目前突破高频上限来实现超宽带无源集成器件的佼佼者,它通过铁氧体与电子陶瓷双相共存、离子互掺杂与替代、双相晶面织构生长而形成。如果在射频段,可采取NiZnCu铁氧体与BaTiO3电子陶瓷复合,以低熔点化合物做低温烧结助熔剂;如果在微波段,可采取旋磁铁氧体与微波陶瓷复合,以低熔点玻璃做低温烧结助熔剂。新型双性能材料既可突破射频段手机无源集成器件的截止频率上限,又可极大降低通信微波基站等器件的损耗,还可解决LTCC工艺中感性/容性界面共融共烧瓶颈,我们的工作就是从这里开始的。本论文主要以低温烧结NiCuZn铁氧体为主体,以钙钛矿介电陶瓷为附体进行双相互扩散掺杂复合研究。实验中我们首先研究了 BaTiO3掺入含量(0～15 wt%)对复合双性能材料成相、微观结构和磁电性能的影响。随着BaTiO3含量的增加,BaTiO3相的衍射峰越来越明显,没有观察到明显的杂相,且晶粒逐渐减小,密度减小。NiCuZn/BaTiO3复合双性能材料的磁性能随着BaTiO3含量的增加而逐渐恶化,饱和磁化强度和磁导率均迅速降低,但介电常数有所增加,且介电损耗也得到改善。随后我们研究了助熔剂Bi2O3、LBBS(Li2O-B2O3-Bi2O3-SiO2)玻璃和LABS(Li2O-Al2O3-Bi2O3-SiO2)玻璃(0～1.5 wt%)对 NiCuZn/BaTiO3 复合双性能材料性能的影响,通过实验我们发现Bi2O3能显著改善复合双性能材料的微观结构和磁电性能。复合双性能材料的晶粒尺寸和密度均随着Bi2O3含量的增加而增大,饱和磁化强度、磁导率也大幅提升,矫顽力减小,介电常数略微增加,介电损耗略微降低。LBBS玻璃和LABS玻璃均能在一定程度上改善NiCuZn/BaTiO3复合双性能材料的性能。相比之下LABS玻璃的助烧作用更为明显。三种助熔剂对于NiCuZn/BaTiO3复合双性能材料微观结构和磁性能的改善作用:Bi2O3>LABS>LBBS,对于介电性能的改善作用:LABS>LBBS>Bi2O3。其次,用NiCuZn铁氧体主体和CaTiO3附体进行互扩散掺杂复合,研究了CaTiO3的掺入含量(0～20 wt%)对材料成相、微观结构、磁性能和介电性能的影响。随着CaTiO3含量的增加,复合双性能材料的密度逐渐减小,晶粒逐渐减小,饱和磁化强度和磁导率都随着CaTiO3含量的增加而逐渐降低,复合双性能材料的截止频率却随之增加。介电常数随着CaTiO3含量的增加而先略微减小再逐渐增加,介电损耗先降低再逐渐升高。紧接着,我们研究了 MABS玻璃助熔剂对复合双性能材料性能的影响,当MABS(MgO-Al2O3-Bi2O3-SiO2)玻璃含量从0增加至1.5 wt%时,复合双性能材料的晶粒尺寸、密度、饱和磁化强度、磁导率、介电常数均逐渐增加,介电损耗逐渐减小。继续增加MABS玻璃含量至2.0 wt%时,复合双性能材料的晶粒尺寸、密度、饱和磁化强度、磁导率、介电常数均有所减小,而介电损耗增加,所以MABS玻璃助熔剂的最佳添加量为1.5 wt%。本章最后再研究了Nd掺杂后的BNTO、CNTO与NCZF铁氧体复合后的双性能材料性能变化。Nd掺杂后的BNTO、CNTO介电常数均有所减小,但QXf值大幅增加。用10 wt%的量与NCZF 铁氧体复合后,对比复合双性能材料的磁导率有:CNTO>BNTO>CTO>BTO,介电常数有:BTO>CTO>CNTO>BNTO,介电损耗有:BTO>CTO>BNTO>CNTO。另外,在NiCuZn/BaTiO3体系基础上,分别研究了用Co2O3取代部分NiCuZn铁氧体和CaCu3Ti4O12(CCTO)取代部分BaTiO3形成的复合双性能材料的磁电性能。Co2O3的加入使复合双性能材料中形成了杂相Ba2Ti9O20相和Ba6Co4012相,原BTO相逐渐减少。但Co2O3的加入也使复合双性能材料中铁氧体晶粒长大,密度逐渐增加。Co2O3含量的增加,NCZF铁氧体含量的减少,使复合双性能材料的饱和磁化强度略微有所减小,且降低了材料的磁导率,但大大增加了材料的截止频率和Q值。与此同时Co2O3的加入减小了复合双性能材料的介电常数,但同时也降低了材料的介电损耗。CCTO的加入并未使材料中产生明显的杂相,且当CCTO含量达到5 wt%及以上,BTO含量降低至5 wt%及以下时,材料中的磁性晶粒尺寸增加,孔隙减少。饱和磁化强度增加,矫顽力降低,磁导率也大幅增加,但Q值受到影响,高Q值频段变窄且向低频移动。CCTO的加入使复合双性能材料的介电常数降低,但当加入量不超过5 wt%时,有助于降低材料的介电损耗。最后,我们设计了一款150MHz低通滤波器,采用ADS电路仿真和HFSS三维模型仿真对设计的滤波器结构进行了优化仿真,仿真结果满足设计指标要求。随后采用我们研究的复合双性能材料和LTCC工艺制作了 0805型150MHz低通滤波器,测试结果基本满足设计指标要求,150MHz频率处衰减小于3 dB,350MHz频率处衰减大于20 dB,证明了新材料的优异双性功能。更多还原

【Abstract】 With the rapid advancement of electronic information technology,in particular,the development of high speed,low consumption,and broadband and integration network,low temperature co-firing ceramic(LTCC)system encapsulation and passive integrated device have become the inevitable choice for the 4th-generation(4G)or 5G cellular network technology and base station electronics.However,it is difficult to break through the electronic material cut-off frequency limit and to solve the problems associated with LTCC process involving co-firing of the porcelain with multilayer magnetic ferrite and the electronic ceramics(inductance and capacitance),which constitute the main bottleneck requiring urgent attention.Therefore,development of a new type of LTCC electronic material,which can be used as both inductor material and capacitor material in the same frequency domain with relatively low dielectric loss and magnetic loss,is urgently required.Such an LTCC material is denoted as composite magnetoelectric dual-performance LTCC material.Currently,this composite dual-performance LTCC material is the groundbreaker in achieving ultra-wideband passive integration devices by breaking through the high frequency ceiling.It is formed using the ferrite and electronic ceramics via the interdoping and substitution of ions and the growth of dual-phase crystal texture.For the radio frequency regime development,NiZnCu ferrite and BaTiO3 electronic ceramics composite,with low melting point is adopted as low temperature sintering co-solvent.In contrast,in case of microwave regime development,the material adopts gyromagnetic ferrite and microwave ceramic composite,with low melting point glass as low temperature sintering co-solvent.The new dual-performance material can not only break through the upper limit of cut-off frequency of the passive integrated device in the radio frequency segment of mobile phone,but also significantly reduce the loss of communication of microwave base station devices,and also solve the bottleneck of inductive and capacitive interface fusion and co-firing in LTCC process.In this study,the NiCuZn ferrite with low temperature sintering was used as the principal part,perovskite dielectric ceramics as attachment,and the double diffusion doping composite dual-performance material with NiCuZn ferrite and perovskite dielectric ceramics was studied.First,the effects of dual-performance composite integrating NiCuZn ferrite and BaTiO3(0-15 wt.%)on the phase formation,microstructure,and magneto-electric properties were evaluated.With the increase in the content of BaTiO3,the diffraction peaks of BaTiO3 phase were more obvious,and no other heterophase peak appeared;moreover,the grain size and density decreased gradually.The magnetic properties,such as saturation magnetization,of NiCuZn/BaTiO3 composites gradually deteriorated with BaTiO3 content,and permeability decreased rapidly.Nonetheless,the dielectric constant and dielectric loss were improved.Then the effects of Bi2O3,Li2O-B2O3-Bi2O3-SiO2(LBBS)glass,and Li2O-Al2O3-Bi2O3-SiO2(LABS)glass(0-1.5 wt.%)on NiCuZn/BaTiO3 dual-performance composite material were studied.The experimental result showed that Bi2O3 could significantly improve the microstructure and magnetoelectric properties of the dual-performance composite.The grain size,density,saturation magnetization,and permeability of dual-performance composite increased significantly with Bi2O3 content.Furthermore,coercivity decreased and dielectric constant and dielectric loss increased slightly.Moreover,LBBS glass and LABS glass were found to be responsible for improving the performance of NiCuZn/BaTiO3 composite.The effect of sintering aids in improving microstructure and magnetic properties of NiCuZn/BaTiO3 composites is in the following order:Bi2O3>LABS>LBBS,and improvement of dielectric properties:LABS>LBBS>BiO23.Second,NiCuZn ferrite was used as principal part and CaTiO3 as attachment to allow for mutual diffusion doping.The effects of CaTiO3 content(0-20 wt.%)in NiCuZn/CaTiO3 dual-performance composite on the phase formation,microstructure,magnetic properties,and dielectric properties were studied.The density,grain size,saturation magnetization,and cut-off frequency gradually decreased with CaTiO3 content;however,the permittivity first decreased slightly and then increased gradually.Next,MgO-Al2O3-Bi2O3-SiO2(MABS)glass was added into NiCuZn/CaTiO3 composite.When content of MABS glass was increased from 0 to 1.5 wt.%,the grain size,density,saturation magnetization,permeability,and dielectric constant of these dual-performance composites augmented,and the dielectric loss reduced.When MABS glass content was increased to 2.0 wt.%,the grain size,density,saturation magnetization,permeability,and dielectric constant of the composite reduced,while the dielectric loss increased.Therefore,the optimal addition amount was found to be 1.5 wt.%.Finally,the properties of NCZF ferrite and Nd-doped BNTO and CNTO composite were studied.The dielectric constant of ceramic decreased with Nd doping,but Q×f increased significantly.The content of Nd-doped ceramic was 10 wt.%,and the comparison of the permeability of the composite is as follows:CNTO>BNTO>CTO>BTO,dielectric constant:BTO>CTO>CNTO>BNTO,and dielectric loss:BTO>CTO>BNTO>CNTO.Moreover,based on NiCuZn/BaTiO3 system,composites formed by replacing part of NCZF ferrite with Co2O3 and replacing BTO with CaCu3Ti4O12(CCTO),respectively,were studied.The addition of Co2O3 resulted in the formation of hybrid phases Ba2Ti9O20 and Ba6Co4O12.However,the addition of Co2O3 also caused the increase in grain size and density of ferrite.The increase of Co2O3 content and the decrease of NCZF ferrite content resulted in slight decrease in saturation magnetization and permeability;however,cut-off frequency and Q value increased significantly.Moreover,the addition of Co2O3 reduced the dielectric constant and dielectric loss of the material.The addition of CCTO did not produce obvious impure phase,and when the content of CCTO reached 5 wt.%or above,the content of BTO decreased to 5 wt.%or below,and the magnetic grain size,saturation magnetization,and magnetic permeability increased significantly,and the number of pores and coercivity decreased.However,Q value was affected,and the high Q value band became narrower and moved to the low frequency region.It also caused reduction in the dielectric constant;however,when the addition amount was below 5 wt.%,the dielectric loss of materials was reduced.Finally,a 150 MHz low-pass filter was designed herein.ADS circuit simulation and HFSS three-dimensional model simulation were applied to optimize the filter structure,and the simulation results met the requirements of the design index.Subsequently,the dual-performance composite material studied herein and LTCC process were used to produce a 150 MHz low-pass filter based on the type of 0805 series.The attenuation at 150 MHz frequency was less than 3 dB,and the attenuation at 350 MHz frequency was more than 20 dB.This result proves that the dual-performance of new composite material is excellent.更多还原