微波毫米波用低介电常数低温共烧陶瓷研究进展

在新一代高速无线通信技术推动下，低温共烧陶瓷技术(LTCC)正处于重大变革时期。采用低介电常数(K)、低损耗、谐振频率温度稳定型LTCC作为高频基板材料，可以满足无线技术高速率、低延时、高可靠的需求，是当前热点研究之一。因此商用基板材料的现状和一些候选材料的研究工作被主要评述，重点对玻璃/陶瓷体系、氧化物助烧体系、氟化物助烧体系、本征低温烧结体系等低K值LTCC材料的组成、结构特征、介电性能、热膨胀系数等具体指标及相应优缺点进行了讨论。同时介绍了一些热门体系的改性工作及其毫米波适用性，最后对未来低K值LTCC材料的发展进行展望。     

低温共烧陶瓷用玻璃材料研究进展

低温共烧陶瓷(LTCC)的玻璃材料对基板性能有重要影响.本文介绍了LTCC用玻璃材料的体系分类与性能特点,梳理了组分、工艺等对材料性能的影响规律,对现有较成熟体系进行了重点分析.CaO–B2O3–SiO2微晶玻璃体系基板含大量晶相,介电性能优异,但烧结析晶行为敏感,组分和工艺波动对性能影响较大.PbO–B2O3–SiO...     

低温共烧陶瓷技术前景

介绍了低温共烧陶瓷（LTCC）的概念和特点，总结了LTCC的国内发展现状以及新产品开发进展，最后介绍了LTCC产品的广泛应用。     

低温共烧陶瓷技术及其应用

低温共烧陶瓷(low temperature co-fired ceramic,LTCC)技术是实现电子元件小型化、片式化的一种理想的封装技术,已成为电子元件集成的主要工艺方式,引起了人们的广泛关注。本文详细叙述了LTCC技术的特点、LTCC材料体系、国内外发展现状以及LTCC技术在电子元件集成中的应用。认为利用LTCC技术来实现电源、有源和无源器件的一体化将是今后信息功能陶瓷发展的一个重要方向。我国应该抓住LTCC技术所面临的前所未有的发展机遇,大力开发具有自主知识产权的LTCC技术,整体提升我国在电子集成领域的技术水平和国际竞争力。     

低温共烧陶瓷等七项目入围信息业重大发明

“低温共烧陶瓷（LTcc）”等七大产业前景良好的技术发明项目日前入选2012年信息产业重大技术发明。工信部日前公示了“2012年（第十二届）信息产业重大技术发明评审结果”,共有7个项目入选。低温共烧陶瓷（LTCC）关键材料、工艺技术、及器件设计是其中之一。该设计由清华大学和顺络电子共同完成。低温共烧陶瓷技术（LTCC）是无源电子元件集成和电子元器件高密度封装的关键技术。该技术的产品应用对象主要有手机、蓝牙终端、     

应用于低温共烧陶瓷元件的La2O3-B2O3-TiO2玻璃和BaNd2Ti5O14陶瓷基复合材料

由BaNd2Ti5O14陶瓷和无铅稀土硼玻璃(LBT)合成的玻璃陶瓷复合材料可以用于制备低温共烧陶瓷元器件(LTCC).本研究对这种玻璃陶瓷复合材料进行了检测,并分析探讨了它的相对密度、收缩率和微波介电特性(εr,Q×f0).低温烧结体呈现出可应用的特性,即相对密度高,超过85%,介电常数εr为13～20,Q×f0为2000～10000.结果显示,这种复合材料在制备高频低温共烧陶瓷元器件方面有很好的应用前景.     

电子陶瓷和器件的低温共烧技术

较系统地介绍了电子器件用低温共烧陶瓷(low temperature cofired ceramics,LTCCs)材料,探讨了其工艺中的若干问题。电子器件用低温共烧陶瓷材料包括:玻璃/陶瓷复合材料、结晶化玻璃、晶化玻璃/陶瓷复合材料以及液相烧结陶瓷,其中典型的和最为常用的LTCCs为玻璃/陶瓷(特别是氧化铝)复合材料。正在研究的一些陶瓷介质材料中,Bi基介质材料引起了人们的关注。玻璃/陶瓷复合材料的制备工艺中,应当着重关注和加深了解玻璃的流动性和结晶性、玻璃的起泡、玻璃和陶瓷颗粒间的反应、共烧材料的匹配等问题,从优选材料配方和优化工艺着手,从而获得优质可靠的材质和器件。     

共烧陶瓷多层基板技术及其发展应用

论述了高温共烧陶瓷与低温共烧陶瓷的优缺点，并讨论了多层共烧陶瓷的材料选择、工艺过程与控制，然后在提高材料性能方面提出了一些建议和方法，同时介绍了多层共烧陶瓷的国内外研究状况及今后的发展趋势。     

超低温烧结微波介质陶瓷制备工艺的研究进展

传统方法制备微波介质陶瓷通常需要1 000℃以上高温，不仅工艺周期长、能量消耗高，而且难以实现多种材料体系的集成共烧。如今，无线通讯技术的不断革新和蓬勃发展对微波器件小型化、集成化提出了更高要求，低温共烧陶瓷/超低温共烧陶瓷技术被开发和广泛应用。研究烧结温度更低、烧结效率更高，且微波介电性能优异的节能环保型绿色制备工艺，已经成为全球范围内研究热点之一。液相烧结、热压烧结、微波烧结、放电等离子体烧结、闪烧等烧结工艺的提出促进了低温烧结微波介质陶瓷的发展。最近，又出现了一种新的超低温烧结工艺—冷烧结技术。冷烧结具有极低的烧结温度(一般≤300℃)、可在短时间内实现陶瓷高致密化，且在物相稳定性、复合共烧以及晶界控制等方面有着优势，为超低温烧结工艺以及微波介质材料体系的开发提供了新的契机。     

水基流延法制备掺杂ZnO-TiO_2系微波介质陶瓷及性能研究

利用低温共烧陶瓷(简称LTCC)技术设计制造片式多层微波器件已成为当今的研究热点。ZnO-TiO2系微波介质陶瓷具有介电常数适中、介电损耗低、频率温度系数可调和低温烧结等特点,它是具有开发价值的LTCC微波介质材料。实验结果表明:在ZnO-TiO2系统中加入微量的添加剂MgCO3与ZrO2,构成双元复合取代掺杂系统Zn1-xMgxTi1-xZrxO3,当x值取0.07时,最佳介电性能为:εr为29.4,Qf为4285GHz,τf为-8ppm/℃,且该微波介质陶瓷适合于水基流延成型和低温烧结,为LTCC微波介质陶瓷产业化打下了良好的基础。     

Characteristics of thick film resistors embedded in low temperature co-fired ceramic (LTCC) substrates

Commercial thick film resistors were embedded in low temperature co-fired ceramic (LTCC) substrates, and co-fired with substrates at temperatures between 800 and 900 °C. Adding glass frit and amorphous SiO₂ to calcium borosilicate glass ceramic substrates has not only lowered the shrinkage of the substrates, but also improved adhesion and maintained structure integrity of the resistor films. During sintering, the conductive phase particles in the resistor became agglomerated and sedimented, and glass diffused into the LTCC substrate layer. Increasing the dwelling time, the overall resistivity of the co-fired films decreased due to sedimentation of agglomerated conductive particles. The liquid eutectic phases penetrated into the substrates added with either SiO₂ or glass frit that the volume fraction of conductive particles was increased. The resistivity of the embedded resistors was determined by the volume fraction of conductive particles, which was influenced by the conductive particles sedimentation, microstructure of resistor films, and inter-diffusion between the resistors and substrates.     

The origin of interfacial delamination in Au/ceramic cofired LTCC structure

The interfacial delamination of electrode/ceramic multilayer structure will seriously damage the reliability of low temperature co-fired ceramic (LTCC) module in practical applications. In this work, three kinds of glasses employed in Au electrode are designed and prepared to study the abnormal expansion and delamination process in the Au/ceramic LTCC multilayer structure. The interfacial delamination in the co-fired structure is found to be attributed to the abnormal expansion of glass in respect to Au electrode at high temperature, which is originated from the enlarged closed pores during the co-firing process. This conclusion is further confirmed by co-firing the sample in a low-pressure condition. The mechanism and elimination of interfacial delamination here provides a feasible solution for the design of novel glasses in Au electrode for LTCC applications.     

CaO含量对CBAS玻璃/Al2O3低温共烧陶瓷的影响

本文主要研究了CaO含量对CaO-B₂O₃-Al₂O₃-SiO₂(CBAS)玻璃/Al₂O₃低温共烧陶瓷结构和性能的影响。利用DSC、FTIR、XRD、SEM等测试方法对玻璃和低温共烧陶瓷的结构进行表征与分析。研究结果表明,CaO含量低于40%(质量分数,下同)时,由其引入的游离氧增加破坏了网络结构,降低玻璃黏度。CaO含量为40%及以上时,Ca²⁺与[SiO₄]四面体形成较大的阴离子基团,增大玻璃黏度,提高玻璃化转变温度。CaO会促进CaSiO₃和Ca₂SiO₄的析出和CaSiO₃向Ca₂SiO₄的转变。CaO含量增加导致陶瓷的致密度先增加后减少,晶相尺寸增大,使陶瓷的密度、抗折强度和介电常数先增大后减小。当CaO含量为40%时,样品综合性能最好,密度最大为2.94 g/cm³,抗折强度为153.44 MPa,介电常数为9.69。     

BaO-Al2O3-B2O3-SiO2玻璃/SiO2高膨胀低温共烧陶瓷研究

用BaO-Al2O3-B2O3-SiO2玻璃与二氧化硅复合的方法制备了高膨胀系数低温共烧陶瓷。实验首先制备一组玻璃材料,通过热膨胀测试、DTA等方法研究了玻璃的热学性能,然后用玻璃与石英、方石英和鳞石英晶体按一定比例复合制得高膨胀低温共烧陶瓷。通过烧结试验、XRD等分析方法研究了复相陶瓷材料的烧结收缩性能、晶相组成、热膨胀系数和介电常数。结果表明:50%BaO-7.5%Al2O3-30%B2O3-12.5%SiO2玻璃具有较低的转变温度(520℃)。该玻璃与鳞石英晶体以1:1的比例复合,850℃/10min烧结可以获得热膨胀系数为12.18×10-6K-1、介电常数为5.37的低温共烧陶瓷。     

Interactions between Ruthenia-Based Resistors and Cordierite–Glass Substrates in Low-Temperature Co-fired Ceramics

Low-temperature co-fired ceramics (LTCCs) that are composed of a RuO₂-based resistor and a cordierite–glass substrate have been sintered at temperatures of 850° and 900°C. The microstructure of the resistor/substrate interface has been investigated using scanning and transmission electron microscopy, and its correlation to the overall resistance has been discussed. X-ray diffractometry has revealed that lead ruthenate pyrochlore (Pb₂Ru₂O_6.5) in peak-fired thick-film resistors (TFRs) disappears and the co-fired samples contain only RuO₂ in the resistor film when sintered at 900°C. The overall resistance of the LTCC resistors is increased by a factor of ∼3 when temperature is increased from 850°C to 900°C. The cordierite–glass composition of the initial substrate reacts with glass in the resistor film. The greatly extended layer of the resistor/substrate interface that contains the conductor particles is either broad or diffuse, which contrasts the abrupt interface that often is observed in conventional TFRs. This layer contains predominantly faceted platelike crystals of anorthite, in addition to other phases (such as diopside, sapphirine, and cristobalite) that apparently crystallize during co-firing as vitrification and chemical reactions between glass compositions of the substrate and the resistor occur. The increase in the resistance of the LTCC resistors is attributed to the interruption of the conducting path by platelike anorthite crystals that are produced in the resistor/substrate interface when subjected to co-firing.     

Viscous Flow as the Driving Force for the Densification of Low-Temperature Co-Fired Ceramics

Filled glass–ceramic composites, like low-temperature co-fired ceramics (LTCC), must densify at temperatures <900°C. The densification mechanism of LTCC is often described by liquid-phase sintering. The results of this paper clearly show that densification of ceramic-filled glass–composites with a glass content above 60 wt% can be attributed to viscous sintering, which is decisively controlled by the viscosity of the glass during the heat treatment. This is demonstrated by the experimental determination of the viscosity of a MgO–Al₂O₃–B₂O₃–SiO₂ glass dependent on temperature, by investigation of the wetting behavior of the glass on the ceramic filler mullite, and of the microstructural development. It was found that the glass does not wet the filler material in a temperature range up to 1000°C. Therefore, liquid-phase sintering can be excluded. Independent of any wetting effect and therefore in the absence of capillary forces, densification starts at a temperature of 750°C, which corresponds to a viscosity of 10^9.5 dPa·s. This densification can be attributed to viscous flow of the glass matrix composite.     

烧结升温速率对低温共烧陶瓷基板性能的影响

烧结是低温共烧陶瓷(LTCC)基板工艺中关键工序之一,对LTCC基板的各项性能指标具有重要的影响。本文以国产MG60生瓷带为研究对象,研究了不同烧结升温速率对LTCC基板介电性能、翘曲度、膜层附着力、抗折强度等性能指标的影响,分析了基板性能变化的原因。结果表明,当升温速率为8 ℃/min时,基板介电常数为5.788,介电损耗为8.21×10^-4,基本无翘曲,烧结致密,附着力强,抗折强度达到175 MPa。     

Oxyfluoride glass-silica ceramic composite for low temperature co-fired ceramics

Glass/ceramic composite materials based on CaF₂–AlF₃–SiO₂ oxyfluoride glass and silica ceramic filler were prepared. The sintering behavior, phase composition and dielectric property of oxyfluoride glass/silica ceramic composites, as well as its compatibility with Ag electrode, were investigated. The results show that the glass/ceramic composite system can be sintered at 825 °C. When the amount of SiO₂ increased from 0 to 20 wt.%, the shrinkage decreased from 17.0 to 14.5%, and the dielectric constant decreased from 5.9 to 5.4, while the thermal expansion coefficient (20–200 °C) increased from 6.0 to 10.1 ppm/°C. The sintered samples had low dielectric losses less than 0.002 and high flexural strengths. This novel glass/ceramic composite system exhibits good sintering compatibility with silver paste, which makes it a promising candidate for low temperature co-fired ceramic application.     

分散剂对低温共烧陶瓷流延浆料流变性能的影响

本文探究了蓖麻油、BYK-22552、聚乙烯吡咯烷酮(PVP)、TEGO-700四种分散剂对CaO-B₂O₃-La₂O₃玻璃/氧化铝低温共烧陶瓷(LTCC)流延浆料分散性的影响,并进一步对该体系浆料流变性能、触变性能、固相体积分数以及沉降性能方面进行了研究,通过红外光谱分析研究了四种分散剂的分散机理并给出了解释。结果表明,当分散剂TEGO-700用量为粉体质量的2%时,流延浆料具有最小黏度(1 650 mPa·s)与最佳触变恢复性。在流延成型最佳黏度2 000 mPa·s下,浆料具有最大固相体积分数(37.2%)与优异的沉降性能。该浆料流延成型得到的柔性生瓷带表面平整且厚度均一,表面粗糙度为144 nm。烧结得到的基板材料表面无气孔、裂纹等明显缺陷,烧结致密化程度高,表面粗糙度为210 nm,40 GHz下测得介电常数与介电损耗分别为6.257和1.431×10^-3。     

Improvement of gold electrode conductivity after cofiring with CaO–B2O3–SiO2 green tapes for LTCC application

The cofiring process of Au paste containing various amount of glass additive with different properties and CaO–B₂O₃–SiO₂ (CBS) green tapes was investigated. The initial shrinkage temperature of Au paste was strongly associated with the softening point and the content of glass additive. The swell of sample and its mechanism during cofiring process was reported. The sheet resistivity of Au electrode was greatly depended on the content of CBS glass additive. When the content of CBS glass additive with the softening point of 704 °C was 3 wt %, the Au electrode exhibited the highest conductivity with the sheet resistivity of 2.4 mΩ/sq. The results obtained in this paper revealed the relationship between the glass additive and cofiring defects of Au electrode in the metal/ceramic multilayer structure, which gave an avenue to manufacture Low temperature co-fired ceramics (LTCC) modules with good quality.