采用金锡合金的气密性封装工艺研究

根据功率器件的气密性封装要求,设计了完整的金锡封焊工艺方法和流程,研究了工艺中的技术难点,提出了确保封装工艺稳定性和可靠性的技术要点.实验选甩Au80Sn20预成型焊环作为封接材料对器件进行气密性封装.通过大量试验得出了最佳工艺曲线(包括温度、时间、气氛和压力等).密封后的产品在经受各项环境试验和机械试验后,其结构完整性、电学特性、机械牢固性和封装气密性均能很好地满足要求,证明了采用倒置型装配的金锡封焊工艺的可行性及优越性.     

Au/Sn共晶键合技术在MEMS封装中的应用

研究了Au/Sn共晶圆片键合技术在MEMS气密性封装中的应用。设计了共晶键合多层材料的结构和密封环图形,盖帽层采用Ti/Ni/Au/Sn/Au结构,器件层采用Ti/Ni/Au结构,盖帽层腔体尺寸为4.5 mm×4.5 mm×20μm,Au/Sn环的宽度为700μm,优化了键合工艺,对影响气密性的因素(如组分配比、键合前处理和键合温度等)进行了分析。两层硅片在氮气气氛中靠静态的压力实现紧密接触。在峰值温度为300℃、持续时间为2 min的条件下实现了良好的键合效果,其剪切力平均值达到16.663 kg,漏率小于2×10-3 Pa·cm3/s,满足检验标准(GJB548A)的要求,验证了Au/Sn共晶键合技术在MEMS气密封装中的适用性。     

大腔体器件气密性焊接技术研究

阐述了大腔体器件的储能焊焊接技术，讨论了焊接基本要素，建立了焊接能量模型。分析了影响气密性的主要因素，通过改进焊接技术和优化工艺参数，解决了大腔体器件的气密性焊接技术问题。目前，大腔体器件(150—200mm周长，对角线≤70mm)气密性焊接的成品率已达到93％。     

微波器件钎焊气密封装工艺设计

研究了一种可应用于微波器件气密封装的钎焊工艺设计.采用有限元仿真软件计算了搭接型微波器件钎焊封装模型,以Sn63Pb37焊料钎焊外引线和盖板为基础,探索出钎焊密封的边界条件和适当的工艺参数并延伸拓展.试验证明,能够实现盒体与盖板的气密性钎焊封装且不影响后续喷涂工艺.使用扫描电镜对焊缝进行检查,焊缝致密无空洞,金属化层厚...     

微波LNA高可靠组装工艺

讨论了微波低噪声放大器(LNA)气密性封装、水气含量控制、高可靠性组装等集成工艺技术.分析了腔体、盖板的尺寸配合以及质量因素对气密性封装的影响;讨论了材料控制、元器件选择、氮气系统对水气含量的影响;阐述了在组装工艺中,如共晶、小焊盘键合等关键工艺技术.通过此方法研制的低噪声放大器满足性能指标及环境试验要求.     

微波腔体选区镀金工艺技术应用研究

随着微电子技术的飞速发展,微波组件集成度越来越高,整体镀镍的微波腔体容易氧化,致使电阻增大,难以满足混合集成电路组件中对接地敏感元器件的装配要求,整体镀金的微波腔体难以满足大量绝缘子连接器一次性锡铅焊接的气密性,同时,焊料流布难以受控,该文通过微波腔体选区镀金工艺的应用验证,包括镀层外观、镀层厚度、镀层结合力、接地电阻以及焊接气密性等,表明微波腔体选区镀金工艺能够有效地提高微波组件集成质量和效率。     

应用BCB材料进行硅-玻璃气密性封装的实验与理论研究

应用苯并环丁烯(BCB)材料对硅片和玻璃片进行了250℃下的圆片级低温键合实验,同时进行了300℃下的硅片与玻璃片阳极键合实验,并对其气密性和剪切力特性进行了对比研究.测试结果表明:在250℃的低温键合条件下,经过500kPa He气保压2h,BCB封装后样品的气密性达到(5.5±0.5)×10-4Pa cc/s He;剪切力在9.0～13.4 MPa之间,达到了封装工艺要求;封装成品率达到100%.这表明应用BCB材料键合是一种有效的圆片级低温气密性封装方法.还根据渗流模型理论,讨论了简易模型下气密性(即渗流率)和器件腔体边缘到划片边缘的间距的关系.     

应用BCB材料进行硅-玻璃气密性封装的实验与理论研究

应用苯并环丁烯(BCB)材料对硅片和玻璃片进行了250℃下的圆片级低温键合实验,同时进行了300℃下的硅片与玻璃片阳极键合实验,并对其气密性和剪切力特性进行了对比研究.测试结果表明:在250℃的低温键合条件下,经过500kPa He气保压2h,BCB封装后样品的气密性达到(5.5±0.5)×10-4Pa cc/s He;剪切力在9.0～13.4 MPa之间,达到了封装工艺要求;封装成品率达到100%.这表明应用BCB材料键合是一种有效的圆片级低温气密性封装方法.还根据渗流模型理论,讨论了简易模型下气密性(即渗流率)和器件腔体边缘到划片边缘的间距的关系.     

应用BCB材料进行硅-玻璃气密性封装的实验与理论研究

应用苯并环丁烯(BCB)材料对硅片和玻璃片进行了250℃下的圆片级低温键合实验，同时进行了300℃下的硅片与玻璃片阳极键合实验，并对其气密性和剪切力特性进行了对比研究. 测试结果表明：在250℃的低温键合条件下，经过500kPa He气保压2h, BCB封装后样品的气密性达到(5.5±0.5)E-4Pacc/s He；剪切力在9.0~13.4MPa之间，达到了封装工艺要求；封装成品率达到100%. 这表明应用BCB材料键合是一种有效的圆片级低温气密性封装方法. 还根据渗流模型理论，讨论了简易模型下气密性（即渗流率）和器件腔体边缘到划片边缘的间距的关系.     

倒装焊器件的密封技术

倒装焊的底部填充属非气密性封装,并且受倒装焊凸点焊料熔点、底部填充有机材料耐温限制,使得倒装焊器件的密封结构设计和工艺设计受限。文章结合气密性器件使用要求,设计了两种不改变现行倒装焊器件制造工艺、器件总体结构[3]的密封技术,经过分析论证以及工艺实验,确认其是可行的。密封的器件能够满足MIL-883G中有关气密性、内部水汽含量、耐腐蚀(盐雾)、耐湿以及机械试验等[6~7],密封结构、密封工艺均是在现有封装工艺条件基础上进行,具有非常强的可行性。     

金属化花粉红外、微波特性测试与分析

针对当前包覆型复合功能材料的需求,利用化学镀铜方法制备了表面镀铜的金属化花粉,对金属化花粉的形态、红外与微波特性进行了测试与分析。SEM图显示花粉金属化后形态保持良好,不发生破裂或变形,镀层厚度较均匀、致密。外层包覆的金属镀层使颗粒显示出特殊的红外与微波特性,而轻质花粉内核保证了颗粒具有较低的质量密度。研究结果表明:金属化花粉具有作为红外与微波波段材料的潜力。     

陶瓷绝缘子的测试与改进

金属墙镶嵌氧化铝陶瓷绝缘子是微波毫米波芯片广泛运用的一种封装外壳形式,而绝缘子则是封装外壳的关键组成部分,它连接了封装外壳内的器件和外部的模块,所以它的特性直接影响所封装器件或模块的微波性能。文章通过对一种现有的镶嵌类封装外壳的陶瓷绝缘子利用电磁场仿真软件HFSS进行微波S参数仿真设计、用普通高温共烧陶瓷（HTCC）工艺加工后,进行测试及改进,减小了陶瓷绝缘子的微波传输损耗和驻波比,从而提高了外壳使用截止频率。     

Quasi hermetic packaging for new generation of spaceborn microwave equipment

This paper presents the introduction of the quasi hermetic encapsulation of microwave hybrids for space application through different approaches evaluated at Thales Alenia Space – France. Thanks to the improvement for many years of microwave organic materials, it is now realistic to propose advanced packaging solutions like the chip on board approach with glob top encapsulation of active devices directly bonded on printed circuit boards for space applications. To validate this packaging approach, very significant reliability test-plans have been proposed and performed on the different technological processes and materials in agreement with standard space quality requirements. Results will be presented and a discussion on the nature of the stresses applied during the tests will be proposed.     

Microstrip ring resonator technique for measuring microwaveattenuation in high-Tc superconducting thin films

Microwave attenuation of high-T_c superconducting (HTS) films sputtered on MgO and ZrO₂ were measured using a microstrip ring resonator circuit. The results of Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O resonators were compared to those for gold-plated resonators of identical design. The losses of superconducting and gold-plated films were determined from unloaded Q-factor measurements. The attenuation of Y-Ba-Cu-O film on an MgO substrate is approximately 31% lower than that of gold films at 6.6 GHz and 33% lower at 19.2 GHz for temperatures below 50 K. The approach of using microstrips to characterize microwave losses shows the usefulness of HTS films in integrated circuit technology     

Room-temperature continuous-wave operation of long wavelength (l ?9.5 lm) MOVPE-grown quantum cascade lasers

High-power continuous-wave operation of long wavelength quantum cascade lasers grown by metal organic vapour phase epitaxy is reported. The lasers have been processed as buried heterostructures with thick gold-plated contacts. The devices emit at a wavelength of 9.5 mum with output powers of several hundreds of milliwatts at room temperature.     

High-power C band Read IMPATT diodes

A GaAs multimesa Read IMPATT-diode structure has been developed for operation in C band. Such devices give reproducible oscillator power output levels in excess of 10 W c.w. at 5 GHz. Junction temperature rises less than1 80 deg C are observed during high-power operation. The diodes are constructed with an integral gold-plated heatsink and bonded with Au : Sn eutectic solder in a small package.     

High-speed low-voltage modulation with a nonsymmetric Mach-Zehnderinterferometer

The authors demonstrate broadband optical modulation with a Ti:LiNbO₃ nonsymmetric interferometer at microwave frequencies up to 16 GHz. The 3-dB bandwidth of 8.7 GHz is only slightly less than the theoretical limit of 9.6 GHz for a 1-cm-long device. The device uses a 2-μm-thick gold-plated asymmetric stripline electrode, with a characteristic impedance of 40 Ω and ohmic loss of 3 dB/cm at 10 GHz. The DC switching voltage is 6.5 V, and the on/off ratio is -16 dB. Fabrication tolerances in the nonsymmetric interferometer are much less strict than for directional coupler modulators with comparable performance, making this device a better candidate for use in communications systems     

GaAs Schottky—Read diodes for x-band operation

High-efficiency performance of GaAs Schottky-Read IMPATT diodes has been observed at X-band frequencies. The highest efficiency measured was 26.1 percent with 2.5-W continuous-wave (CW) output power at 8.8 GHz for a single-mesa diode while multiple-mesa diodes have delivered more than 7 W at X band. The diodes were fabricated from multiple-layer epitaxial material with gold-plated heat sinks. Details of materials preparation and diode fabrication are presented. Theoretical calculations of diode breakdown voltage and efficiencies have been made as a function of the structural properties of the diodes. Good agreement has been obtained between the experimental microwave oscillator performance and the theoretical calculations.     

Human Cell Encapsulation in Gel Microbeads with Cosynthesized Concentric Nanoporous Solid Shells

Encapsulation of therapeutic cells in core–shell microparticles has great promise for the treatment of a range of health conditions. Unresolved challenges related to control of the particle morphology, mechanical stability, and immunogenicity hinder dissemination of this promising approach. Here, a novel polymer material for cell encapsulation and a combined novel, easy to control, synthesis method are introduced. Core–shell cell encapsulation is demonstrated with a concentric core–shell morphology formed during a single UV exposure, resulting in particles that consist of a synthetic hydrogel core of polyethylene glycol diacrylate and a solid, but porous, shell of off‐stoichiometric thiol‐ene. The encapsulated human cells in 100 µm diameter particles have >90% viability. The average shell thickness is controlled between 7 and 13 µm by varying the UV exposure, and the shell is measured to be permeable to low molecular weight species (<180 Da) but impermeable to higher molecular weight species (>480 Da). The unique material properties and the orthogonal control of the microparticle core size, shell thickness, shell permeability, and shell surface properties address the key unresolved challenges in the field, and are expected to enable faster translation of novel cell therapy concepts from research to clinical practice.