低温共烧陶瓷射频无源集成基础技术研究进展

低温共烧陶瓷(LTCC)技术是当今世界射频无源集成的关键技术,嵌入式无源元件设计与模型化是LTCC重要基础技术。本文介绍了LTCC射频无源集成的关键技术,并着重介绍了射频无源元件(如电感、电容)的等效电路模型的发展过程。     

低温共烧陶瓷(LTCC)技术应用进展

作为一种新兴的集成封装技术,低温共烧陶瓷(LTCC)技术以其优良的高频和高速传输特性、小型化、高可靠而备受关注.介绍了低温共烧陶瓷技术的工艺、材料特性、应用及发展趋势,分析其在功能模块领域应用的可行性.     

LTCC/LTCF多层片式器件自动建模技术

针对LTCC/LTCF多层片式器件设计效率低下的问题，提出采用IronPython脚本语言实现自动化的版图检查和仿真建模的技术。介绍了多层片式器件的设计流程，采用VS2013+PTVS编程平台，开发了基于IronPython的脚本程序控制ANSYS EM软件，实现自动导入版图文件和自动建模，重点介绍脚本流程和处理图层信息的关键算法。应用于LTCF微磁变压器、LTCC电感器、片式共模滤波器等多层片式结构器件的设计，可显著提升设计效率。     

不同基板的GaN器件集成模块传热分析及热优化

分别对基于3种基板,即印刷电路板(PCB)、覆铜陶瓷板(DBC)及低温共烧陶瓷板(LTCC)的氮化镓(GaN)器件集成模块的传热性能进行对比分析。结果表明,DBC模块的结-空气热阻最低,较高的是LTCC模块,最高是PCB模块。在自然对流情况下,DBC模块的结-空气热阻比PCB模块低约20%,强制对流情况下低约50%。LTCC基板相对于常用PCB基板及DBC陶瓷基板优势不显著。设计制造了基于PCB基板的GaN器件降压转换器集成模块,并对其传热性能进行热仿真及实验研究。根据热仿真模型,分析了热通孔对传热的强化作用及平行布置时器件之间的间距对其传热性能的影响。结果显示通过在PCB基板上打热通孔可显著提高模块的传热性能,从无通孔变为有通孔(通孔面积为10%芯片面积),即可使模块的结-空气热阻降低12%。     

LTCF/LTCC 异质材料共烧EMI滤波器设计与制作

采用低温共烧陶瓷(LTCC)/低温共烧铁氧体(LTCF)相结合异质材料共烧工艺制作 EMI 滤波器,介绍了器件的设计、仿真方法、制作工艺与性能测试结果.通过介质材料掺杂改性和优化流延工艺,解决了异质材料低温共烧匹配技术难点,实现了LTCC/LTCF异质材料良好的共烧兼容特性.EMI滤波器性能分析和测试结果表明,器件具有高的插入损耗,可在宽频率范围内防止EMI噪声.     

FPGA的结构原理及在交流伺服电机中的应用

现场可编程门阵列(FPGA—Field Programmable Gate Array)是新型的大规模集成逻辑器件。它采用高级计算机辅助设计技术进行器件的开发与设计，其优越性大大超过普通TTL集成门。重点介绍了FPGA的基本组成原理及在交流伺服电机中的应用。     

集成光栅器件与微细加工技术

集成光栅器件是光集成电路(OIC)和光电子集成电路(OEIC)中的重要功能器件,真有波导材料中光波长量级的微细周期结构,其制作技术要求极为苛刻,本文侧重介绍在集成光栅器件制备中的全息光刻、电子束和离子束等微细加工技术。     

现场可编程门阵列的结构与设计

现场可编程门阵列(FPGA——Field Programmable Gate Array)是上世纪80年代末发展起来的新型大规模集成逻辑器件。它采用高级计算机辅助设计技术进行器件的开发与设计，其优越性大大超过普通TTL集成门。重点介绍了FPGA的基本组成原理及设计方法。     

FPGA的结构原理及在交流伺服电机中的应用

现场可编程门阵列 (FPGA—FieldProgrammableGateArray)是新型的大规模集成逻辑器件。它采用高级计算机辅助设计技术进行器件的开发与设计 ,其优越性大大超过普通TTL集成门。重点介绍了FPGA的基本组成原理及在交流伺服电机中的应用。     

电源设备保护电路的优化设计

介绍了3种新型保护器件的原理与应用,包括有源电磁干扰(EMI)滤波器、集成过电压保护器件和集成过电流保护器件。上述器件可广泛应用于电源设备保护电路中。     

基于LTCC技术的耦合电感

耦合电感已被广泛应用于负载点电源(Point of Load,POL),以提高其稳态和动态性能。为了进一步提高系统的集成度和功率密度,耦合电感的封装集成技术近年来引起了广泛的关注。在这样的研究背景下,本文对基于低温共烧陶瓷工艺(Low Temperature Co-fired Ceramic,LTCC)的耦合电感的封装集成技术进行了研究。首先,针对低温高烧陶瓷工艺的特点,本文提出了四种不同的耦合电感结构并对它们进行了分析、仿真;其次推导出估算电感值的简单有效的数学模型,并通过仿真表明模型的准确性;然后,为了更好的测试低温共烧陶瓷耦合电感的特性,本文制作了一个超薄的易于三维集成的耦合电感样品,并给出了其电感值特性的测量结果;最后,耦合电感样品被应用于一台1MHz、12V输入、1.2V/45A输出的两相交错并联降压斩波电路中,测试其在功率电路中的性能。     

The application of thick-film technology in C-MEMS

Laminated 3D structures made using low-temperature co-fired ceramic (LTCC) technology are practical for ceramic micro-electro-mechanical systems (C-MEMS). The sensors for mechanical quantities, and/or actuators, are fundamental parts of MEMS. Thick-film resistors can be used to sense the mechanical deformations, and thick-film piezoelectric materials can be used as electro-mechanical transducers in a C-MEMS structure. The integration of these thick-film materials on LTCC substrates is in some cases difficult to realise due to interactions with the rather glassy LTCC substrates. The subject of our work is an investigation of thick-film materials for electro-mechanical transducers (sensors and actuators) and their compatibility with LTCC substrates. Resistors made with commercial thick-film resistor materials for use as sensors on LTCC substrates have been investigated and evaluated. Ferroelectric ceramic materials based on solid solutions of lead zirconate titanate (PZT) with low firing temperatures around 850°C were developed for thick-film technology and evaluated on LTCC substrates.     

Thermal and dielectric properties of glass-ceramics sintered based on diopside and anorthite composition

To develop a low dielectric constant of LTCC substrate, we studied the effect of the sintering and crystallization behavior on the dielectric properties of a sintered body by mixing a CaO–Al₂O₃–SiO₂ frit and a CaO–MgO–SiO₂ frit for a low dielectric constant of LTCC substrates. In this work, the two glass frits were mixed at different proportions and sintered at 860~920°C. After sintering at 900^oC for 1h, the glass frits crystallized into diopside and anorthite. The sintered bodies exhibited dielectric properties, ? _r?=?6~8.6 at 1 GHz, which is an essential condition for a substrate in microwave devices. The results suggest that the glass-ceramic can be applied to low dielectric LTCC materials in the electronics packaging industry.     

Low temperature cofirable MnZn ferrite for power electronic applications

A new MnZn ferrite tape material for sintering at 900 °C and its performance in power electronic embedded multilayer inductors of several μH inductance are described. The low sintering temperature is achieved by optimizing powder processing and sintering additives. The material is suited for processing within the low temperature cofired ceramics (LTCC) technology and it is particularly compatible with low loss Ag metallization. Although reduced by a factor of two compared to high-temperature sintered material, its relative amplitude permeability of 700 allows for numerous device applications below the Curie temperature of 260 °C. Volumetric losses are not affected by the new material formulation since increased hysteresis losses are compensated by reduced eddy current losses. Power line filters with ceramic integrated inductors and surface mounted capacitors exhibit a current capacity of up to 10 A and a shift in cutoff frequency compatible with the measured B–H curve of the material. By integration of these inductors with conventional dielectric LTCC tapes a strain-induced permeability quenching is revealed and attributed to magnetostriction. Therefore good thermal matching between tape materials is needed, but the effect also permits construction of variometers and pressure sensors without moving mechanical parts.     

An investigation of thick PZT films for sensor applications: A case study with different electrode materials

Lead zirconate titanate (PZT) is a piezoelectric material that can sense or respond to mechanical deformations and can be used in ceramic micro-electro-mechanical systems (C-MEMS). A thick-film paste was prepared from a pre-reacted PZT powder (PbZr_0.53Ti_0.47O₃) and thick-film technology (screen-printing and firing) was used to deposit the PZT layers on LTCC tapes and on alumina substrates. The microstructural, electrical and piezoelectric characteristics of the thick PZT films on relatively inert alumina substrates and on LTCC tapes were studied. Preliminary experiments indicated that due to the interaction between the printed PZT layers and the LTCC substrates during firing the electrical characteristics deteriorate significantly. To minimise the influence of substrate-film interactions different electrode materials and the use of additional intermediate layers as a barrier were evaluated. The dielectric permittivities, dielectric losses, and piezoelectric coefficients (d ₃₃) were measured. The dielectric permittivities of the thick films fired on LTCC substrates were lower (210 with gold electrodes and 430 with silver electrodes) than those measured on alumina substrates (500). The piezoelectric coefficients d₃₃ were measured with a Berlincourt piezometer. The d ₃₃ values measured on the LTCC substrates were relatively low (60–80 pC/N) compared with the values obtained for the alumina substrates (around 140 pC/N). The lower dielectric constants and piezoelectric coefficients d ₃₃ of the films on LTCC substrates are attributed to the formation of phases with a lower permittivity. This was a result of the diffusion of SiO₂ from the LTCC into the active PZT layer. The diffusion of silica was confirmed by the SEM and EDS analyses.     

微波铁氧体器件现状及新一代集成化微波铁氧体器件展望

阐述了微波铁氧体器件发展现状,指出了微波铁氧体器件当前应该发展的技术方向和亟需突破的关键技术,强调微波铁氧体器件小型化和便于IC集成要求迫在眉睫。为实现微波铁氧体器件的小型化,从微波铁氧体器件基本原理入手,论述了圆极化概念在微波铁氧体器件功能实现和性能优化方面的重要作用,提出了采用绝缘多导体磁性结构实现可满足小型化和便于集成化要求的新一代微波铁氧体器件的基本思路。绝缘多导体磁性器件结构可实现多个TEM波模式的混合传输,利用此构造关于磁化偏置方向的正负圆极化波,从而产生显著的非互易传输和电控特性。TEM模式没有低频截止问题,器件尺寸可大体不受波长比拟规则的限制,通过目前日趋成熟的磁性集成化工艺,可实现小型化和便于IC集成化的新一代微波铁氧体器件。     

Engineering strained silicon-looking back and into the future

The purpose of this article is to explain the basics behind straining and report on the current process technologies available to strain CMOS devices. Strained Si enhances the performance of CMOS devices by increasing carrier mobility without having to make them smaller. As the benefits to be gained from scaling transistors continue to decrease, the commercial interest in using strained Si for CMOS devices has spiked. Additionally, strained Si still retains its integratability in CMOS manufacturing processes, unlike any other semiconductor material. Thus the real test for engineers lies in the ability to cost-effectively develop and apply strained Si technology into current CMOS process. Thus new methods for straining Si is integrated into IC manufacturing as industry interest in this technology continues to grow and also increases the speed, performance and functions of the circuits.     

PZT thick films on different ceramic substrates; piezoelectric measurements

The piezoelectric, microstructural and electrical characteristics of thick PZT films on relatively inert alumina substrates and on two LTCC tapes, i.e., Du Pont 951 and Electro Science Labs 41020 were studied. A thick-film paste was prepared from the pre-reacted PZT powder (PbZr_0.53Ti_0.47O₃) and printed and fired on LTCC tapes and on alumina substrates, respectively. Dielectric permittivities, dielectric losses, remnant polarizations and coercive fields were measured. The dielectric constants (100–150) of thick films fired on LTCC substrates are low. The piezoelectric coefficients d ₃₃ were measured by different methods, i.e. Berlincourt piezometer, interferometry and piezoresponse force microscope (PFM). The d ₃₃ values on LTCC substrates are low (30–70 pm/V) as compared with values obtained on alumina substrates (around 120 pm/V). Lower dielectric constants and piezoelectric coefficients d ₃₃ of films on LTCC substrates are attributed to the formation of phases with a low permittivity due to the diffusion of silica from LTCC substrates into PZT films. The d ₃₃ constants of samples with different thicknesses of PZT layers (from 20 to 160 μm) at first increase with the increasing thickness of PZT layers and then decrease for thicker films. As the cracks in the structure were not observed the reason for the decreasing d ₃₃ values for thicker films is still unclear.