铜/石墨烯柱复合结构的导热特性

近年来,散热已经成为电子器件的一个重要课题,其中热界面材料受到人们的广泛重视。为了进一步改进热界面材料的性能,采用分子动力学方法计算了碳纳米管与石墨烯复合结构——石墨烯柱的热学特性。结果表明,结构的热学性能可以通过石墨烯层间的纳米管数目加以调节,随着纳米管数目的增多,结构的热导增加并逐渐达到一个饱和值,该值比石墨烯结构的热导大了约50%。这个结果为热界面材料的进一步优化提供了重要的参考。     

金刚石/铜复合散热材料的制备和检测

金刚石/铜复合材料具有高的热导率和可调的热膨胀系数,是一种极具竞争力的新型电子封装材料,可作为散热材料广泛应用于高功率、高封装密度的器件中。文中从工程化的角度出发,对应用中的瓶颈因素进行了研究。为改善其钎焊性能,采用磁控溅射、电镀等方法在金刚石/铜表面获得了附着力、可焊性良好的Ti-Cu-Ni-Au复合膜层。在此基础上进行了钎焊试验,金锡焊料在复合膜层上铺展良好、无虚焊。对金刚石/铜的散热效果与钼铜片做了对比试验,结果表明,在相同条件下,与钼铜热沉片相比,降温幅度超过20℃,具有更优异的散热效果。     

金刚石/硅复合膜的导热特性研究

用金刚石粉,用不同时间在两片镜面抛光的(111)硅基片上分别打磨.两片硅基片打磨后都仍保持镜面特征.采用微波等离子体化学气相沉积系统,利用氢气、甲烷和氧气为前驱气体,在同样参数条件下,在基片上制备了直径5 cm的金刚石薄膜.用扫描电镜和X射线衍射分析两片薄膜结构.分析结果表明其表面形貌基本相同都为(111)择优取向的金刚石薄膜;但X射线衍射分析表明打磨时间较长的薄膜中含有一定量在非晶成分.用热导测试仪测试两薄膜和硅基片的热导率约为:241.7 W/mK,192.9 W/mK和169.3 W/mK.结合扫描电镜和X射线衍射分析结果我们讨论了基底处理对金刚石/硅复合膜的导热特性的影响.     

电子封装材料用金刚石/铜复合材料的研究进展

电子技术的快速发展对封装材料的性能提出了更严格的要求.针对封装材料的发展趋势,金刚石/铜复合材料作为新一代的电子封装材料受到了广泛的重视.概述了金刚石/铜复合材料作为封装材料的优良性能及其制备工艺进展,并对其发展方向进行了展望.     

超高导热金刚石铜复合材料在GaN器件中的应用

金刚石铜具有高导热率和低膨胀系数,可用于大功率芯片的散热热沉.未做处理的金刚石表面非常光滑,不易附着其他金属,由于金刚石性质非常稳定,不容易被强酸和强碱进行表面处理.采用JG-01金刚石铜粗化处理液对金刚石进行粗化处理,而对铜无损伤,提升了金刚石表面结合力.金刚石铜镀层对金锡(AuSn)和锡铅(PbSn)焊料的润湿性满足GJB548B-2005要求.GaN功率放大器芯片采用金刚石铜热沉比铜钼铜热沉结温可以降低12℃.金刚石铜载板镀层润湿性良好,焊接后芯片底部的空洞率不大于3％,热沉焊接后空洞率不大于5％,满足高功率芯片散热要求.按照产品环境适应要求,对GaN功率放大器做了高低温冲击和机械振动两种环境筛选实验,最终满足可靠性考核要求.     

高导热金刚石/玻璃复合材料的制备和性能研究

首先对金刚石颗粒进行化学镀Cu,并控制氧化,从而在金刚石颗粒表面获得Cu-Cu2O复合结构。然后,在800℃无压烧结制备了金刚石/玻璃复合材料,观察了其表面和界面形貌,并测定了其相对密度和热导率。结果表明,通过对镀Cu金刚石的控制氧化,明显改善了玻璃对金刚石颗粒表面的润湿性,避免了玻璃对金刚石颗粒表面的侵蚀,提高了复合材料的热导率;复合材料的热导率随金刚石含量的增加而增加,当金刚石质量分数为70%时,热导率最高达到了14.420W/(m·K)。     

电子封装中高散热铜/金刚石热沉材料的电镀技术研究

随着半导体封装载板集成度的提升,其持续增加的功率密度导致设备的散热问题日益严重。金刚石-铜复合材料因其具有高导热、低膨胀等优异性能,成为满足功率半导体、超算芯片等电子封装器件散热需求的重要候选材料。文章采用复合电镀法成功制备了铜/金刚石复合材料,考察了不同复合电镀的工艺方法、金刚石含量、粒径大小对复合材料微观结构、界面结合以及导热性能的影响。并通过优化复合电镀方式,金刚石添加量等工艺参数,制备了无空洞、界面结合紧密的高导热复合材料;仅添加8.8 vol%的金刚石,使复合材料的导热率从393 W/(m.K)增加到462 W/(m.K)。本技术可以应用于半导体封装领域,并进一步增强芯片的散热性能。     

金刚石-铜复合薄膜热沉基底

本文介绍用ＣＶＤ法在铜的基底上合成金刚石薄膜,并获得金刚石－铜复合材料的方法,测量了金钢石－铜复合薄膜电阻与温度的关系．得到了类金刚石薄膜的能隙宽度为０．７～２．５ｅＶ,多晶金刚石薄膜的禁带宽度为２．６～３．１ｅＶ,金刚石－铜复合薄膜的热导率约为铜的２倍     

基于ZnO/AlN/金刚石温补结构的研究

使用COMSOL软件对ZnO/AlN/金刚石温度补偿结构进行建模分析,计算了该结构Love波模式0和模式1的频率温度系数(TCF)、声速(v)和机电耦合系数(k~2),且讨论了ZnO薄膜厚度h_(ZnO)和AlN薄膜厚度h_(AlN)对这些参数的影响。结果表明,当h_(ZnO)=1μm,h_(AlN)=1.88μm时,温度补偿结构Love波模式1的TCF=0,v=9 208 m/s,k~( 2)=3.84%,说明这种温度补偿结构能应用在高频和温度补偿声表面波器件中。     

Pb对SiCp/Al-1.2Mg-O.6Si-0.1Ti复合材料界面结构的影响

采用搅拌复合方法制备了SiCp/Al-1.2Mg-0.6Si-0.1Ti-1.0Pb复合材料,通过透射电镜研究了复合材料的界面结构.复合材料中增强体SiC与基体合金的界面主要为SiC/Al、SiC/Pb、SiC/Mg2Si,Pb在复合材料中主要以面心立方Pb相形式存在于SiC颗粒的界面上,部分SiC颗粒的界面存在Al4C3.界面Pb相中存在着Ti元素,由于合金元素之间的相互作用使基体合金中的Pb、Ti元素集中存在于SiC的界面上.     

Highly transparent conductive films of thermally evaporated In2O3

Highly transparent (over 90% transmission in the visible range) and highly conductive (resistivity ≈2 × 10^-4 ohm-cm) indium oxide (undoped) films have been produced by thermal evaporation from In₂O₃ + In source in a vacuum chamber con-taining low pressures of O₂, . Film properties are comparable or superior to the best tin-doped indium oxide films that have ever been reported, and excellent reproducibility has been achieved. Hall effect measurements have revealed that the observed low resistivity is primarily a result of the excellent electron mobility (? 70 cm²/V-sec), although the electron concentration is also rather high (≥4 × l0²⁰/cm³). X-ray diffraction measurements show distinctly polycrystal-line In₂O₃ structure with a lattice constant ranging from 10.07Å to 10.11Å. Electrolytic electroreflectance spectra exhibit at least four critical transitions, from which we have determined the direct and indirect optical band gaps (3.56eV and 2.69eV, respectively). Burstein shifts due to the population of electrons in the condition band are also observed. From an internal photoemission study, the work function of the In₂O₃ film has been determined to be 5.0eV. These and other results, along with a discussion of the processing details are reported.     

The xerogel structure of thermally evaporated tungsten oxide layers

Based on ion exchange and chemisorption experiments the structure of thermally evaporated tungsten oxide (THETOX) layers is described as a xerogel of hydrated tungsten hydroxy-oxides. The large internal surface covered with Bronsted acid sites determines the electrochromic properties of the layer. The problems of display-application are discussed in the light of the xerogel structure. Xerogel: dry gel or sintered colloid with dispersion medium air or vacuum The major part of this work was presented at 21st EMC, Boulder, Co., June 27, 1979 and 22nd EMC, Ithaca, N.Y., June 24, 1980     

Preparation and characterization of conductive polypyrrole/kaolinite composites

Conductive polypyrrole (PPy)/kaolinite clay composites were prepared by in situ chemical polymerization of pyrrole in the presence of kaolinite using FeCl₃ as oxidant. The PPy content and conductivity of the composites reached 32.8% and 8.3×10^?2 S/cm at HCl concentrations of 1.5 M and 0.5 M, respectively. The microhardness of the composites containing different amounts of PPy was higher than that of the PPy and kaolinite components. The highest microhardness observed was 30.17 kg/mm² for the composite containing 9.6% PPy. The electrical resistance of the composites was monitored during heating–cooling cycles over the range 5–120 °C. The change in resistance with temperature was more repeatable for the composite than for PPy. The composites were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The humidity-sensing properties were also examined.     

Comparative study of thermally conductive fillers for use in liquidencapsulants for electronic packaging

Thermal management plays a very vital role in the packaging of high performance electronic devices. Effective heat dissipation is crucial to enhance the performance and reliability of the packaged devices. Liquid encapsulants used for glob top, potting, and underfilling applications can strongly influence the package heat dissipation. Unlike molding compounds, the filler loading in these encapsulants is restrained. This paper deals with the development and characterization of thermally conductive encapsulants with relatively low filler loading. A comparative study on the effect of different ceramic fillers on the thermal conductivity and other critical properties of an epoxy based liquid encapsulant is presented     

碳纳米材料在导热聚合物复合材料中的应用

介绍了三种具有较高热导率的碳纳米材料:碳纳米管、纳米石墨片及纳米碳纤维的结构与导热性能,概述了三种碳纳米材料在改善聚合物复合材料导热性能方面的应用,重点分析了碳纳米材料的种类、用量、表面改性方法及复合材料的制备方法对聚合物复合材料热导率的影响,并对含碳纳米材料的导热聚合物复合材料未来的发展方向进行了分析与展望。     

时分复用设备动态帧结构技术研究

针对目前时分复用设备在承载可变速率业务及可变速率传输领域内存在的缺陷,提出了能很好的支持可变速率业务复用和不对称传输的动态帧结构技术。该技术是一种多路复用技术,它可根据支路业务速率的变化来动态改变复接设备的帧结构。给出了动态帧结构的理论基础及实现方法,并简要列出了该技术的性能指标。     

ACF互联可靠性影响因素的研究进展

总结了材料、芯片结构和环境因素等对异向导电胶膜(Anisotropic Conductive Film;ACF)互联可靠性的影响。文献表明,ACF基体树脂的吸湿膨胀系数、粘结强度及玻璃转化温度严重影响组装产品的互联可靠性,而导电粒子的导电性、芯片的结构和焊盘的表面处理方式等对可靠性也有较大影响。文献中的可靠性试验表明,在上面提到的因素中,湿气是影响器件中ACF可靠性的主要因素。     

Effect of thermal aging on the interfacial structure of SnAgCu solder joints on Cu

Interfacial structure plays a great role in solder joint reliability. In solder joints on Cu, not only is Kirkendall voiding at the solder/Cu interface a concern, but also the growth of interfacial Cu–Sn intermetallic compounds (IMCs). In this work, evolution of microstructure in the interfacial region was studied after thermal aging at 100–150 °C for up to 1000 h. Special effort was made during sample preparation to reveal details of the interfacial structure. Thickness of the interfacial phases was digitally measured and the activation energy was deduced for the growth of Cu₃Sn. Kirkendall voids formed at the Cu/Cu₃Sn interface as well as within the Cu₃Sn layer. The thickness of Cu₃Sn significantly increased with aging time, but that of Cu₆Sn₅ changed a little. The interfacial Cu₃Sn layer was found growing at the expense of Cu₆Sn₅. Evolution of the interfacial structure during thermal aging is discussed.