Effect of High Electric Field on Lifetime Performance of Metalized Film Capacitor in Pulsed-power Applications

High energy density capacitor is a key device to power supply source for electromagnetic gun (EMG) system, and extending its lifetime is important for increasing the reliability of the power source. Working in high electric field could affect the capacitor lifetime, and this effect on metallized polypropylene film capacitors (MPPFCs) in pulsed-power applications is studied and presented. Experimental re- sults show that the lifetime of MPPFCs decreases with the increasing peak value of charged electric field, and this decrease could be described by function (L/L0) ∝ (E/E0)–m, where, m=7.32. The lifetime of MPPFCs also decreases with the increase of the reversal coeffi- cients in underdamped circuits, which could be described by (L/L0) ∝ (ln(1/K0)/(ln(1/K))–b, where, b=0.7. These results provide a basis for the lifetime prediction of MPPFCs in pulsed-power applications.

Chlorine Gas Sensors with HPS Film on Interdigitated Capacitors

The Cl2-sensitive heteropolysiloxanes(HPS) film was formed on the interdigital capacitor based on silicon dioxide by means of sol-gel process and spin-on technique.Measurements of interdigital capacitance were performed at room temperature for frequencies 100 Hz,1 kHz and 10 kHz.It is shown that there is a linear relationship between the capacitance and the concentration of chlorine gas.Influences of the measurement frequency and film thickness of silicate on the sensitivity of the sensor to C12 gas were discussed.And organically modified N,N-diethylaminopropyl-trimethoxysilane (APMS) had a much higher sensitivity.

A Bilayer High-Temperature Dielectric Film with Superior Breakdown Strength and Energy Storage Density

The further electrification of various fields in production and daily life makes it a topic worthy of exploration to improve the performance of capacitors for a long time,including thin-film capacitors.The discharge energy density of thin-film capacitors that serves as one of the important types directly depends on electric field strength and the dielectric constant of the insulation material.However,it has long been a great challenge to improve the breakdown strength and dielectric constant simultaneously.Considering that boron nitride nanosheets(BNNS)possess superior insulation and thermal conductivity owing to wide band gap and 2-dimensional structure,a bilayer polymer film is prepared via coating BNNS by solution casting on surface of polyethylene terephthalate(PET)films.By revealing the bandgap and insulating behavior with UV absorption spectrum,leakage current,and finite element calculation,it is manifested that nanocoating contributes to enhance the bandgap of polymer films,thereby suppressing the charge injection by redirecting their transport from electrodes.Worthy to note that an ultrahigh breakdown field strength(~736 MV m^(−1)),an excellent discharge energy density(~8.77 J cm^(−3))and a prominent charge-discharge efficiency(~96.51%)are achieved concurrently,which is ascribed to the contribution of BNNS ultrathin layer.In addition,the modified PET films also have superior comprehensive performance at high temperatures(~120°C).The materials and methods here selected are easily accessible and facile,which are suitable for large-scale roll-to-roll process production,and are of certain significance to explore the methods about film modification suitable for commercial promotion.

Experimental Characterization of ALD Grown Al<SUB>2</SUB>O<SUB>3</SUB>Film for Microelectronic Applications

The study of high dielectric materials has received great attention lately as a key passive component for the application of metal-insulator-metal (MIM) capacitors. In this paper, 50 nm thick Al2O3 thin films have been prepared by atomic layer deposition technique on indium tin oxide (ITO) pre-coated glass substrates and titanium nitride (TiN) coated Si substrates with typical MIM capacitor structure. Photolithography and metal lift-off technique were used for processing of the MIM capacitors. Semiconductor Analyzer with probe station was used to perform capacitance-voltage (C-V) characterization with low-medium frequency range. Current-voltage (I-V) characteristics of MIM capacitors were measured on precision source/measurement system. The performance of Al2O3 films of MIM capacitors on glass was examined in the voltage range from −5 to 5 V with a frequency range from 10 kHz to 5 MHz. Au/Al2O3/ITO/Glass MIM capacitors demonstrate a capacitance density of 1.6 fF/μm2at 100 kHz, a loss tangent ~0.005 at 100 kHz and a leakage current of 1.79 × 10−8 A/cm2 at 1 MV/cm (5 V) at room temperature. Au/Al2O3/TiN/Si MIM capacitors demonstrate a capacitance density of 1.5 fF/μm2 at 100 kHz, a loss tangent ~0.007 at 100 kHz and a lower leakage current of 2.93 × 10−10 A/cm2 at 1 MV/cm (5 V) at room temperature. The obtained electrical properties could indicate a promising application of MIM Capacitors.

Electrical Properties of Compositional Al2O3 Supplemented HfO2 Thin Films by Atomic Layer Deposition

With advanced research for dielectrics including capacitors in DRAMs, decoupling filters in microcircuits and insulating gates in transistors, a lot of demand for the new challenging of high-k materials in semiconductor industries has been emerged. This study explores and addresses the experimental approach for composite materials with one of the major concerns of high capacitance, and low leakage, as well as ease of integration technology. The characteristics of Al2O3 supported HfO2 (AHO) thin films for a series of different Hf ratios with Al2O3 dielectrics by atomic layer deposition demonstrated as a candidate material. A composite AHO films with the homogeneous compositions of Al and Hf atoms into the Al-Hf-O mixed oxide system could stabilize the polycrystalline structure with increasing of dielectric constant (k) and decreasing of leakage current density, as well as a higher breakdown voltage than HfO2 film on its own. 70 nm thick AHO thin films with different composition of Al and Hf contents were prepared by atomic layer deposition technique on titanium nitride (TiN) and silicon dioxide (SiO2) coated Si substrates. Photolithography and metal lift-off technique were used for the device fabrication of the metal-insulator-metal (MIM) capacitor structures. AHO films on TiN/SiO2/Si were measured by semiconductor analyzer and source/ measure system with probe station in the voltage range from -5 to 5 V with a frequency range from 10 kHz to 1 MHz were used to conduct capacitance-voltage (C-V) measurements with low/medium frequency range and current-voltage (I-V) measurements. It was found that Au/AHO/TiN/SiO2/Si MIM capacitors demonstrate a capacitance density of 1.5 - 4.5 fF/μm2 at 10 kHz, a loss tangent of 0.02 - 0.04 at 10 kHz, dielectric constant of 11.7 - 35.5 depending on the composition and a low leakage current of 1.7 × 10-9 A/cm2 at 0.5 MV/cm at room temperature. The acquired experimental results could show the possibility of compositional alloy thin films that could potentially replace or open new market for high-k challenges in semiconductor technology.

Composition change and capacitance properties of ruthenium oxide thin film

Ru O2·n H2O film was deposited on tantalum foils by electrodeposition and heat treatment using Ru Cl3·3H2O as precursor.Surface morphology, composition change and cyclic voltammetry from precursor to amorphous and crystalline RuO2·n H2O films were studied by X-ray diffractometer, Fourier transformation infrared spectrometer, differential thermal analyzer, scanning electron microscope and electrochemical analyzer, respectively. The results show that the precursor was transformed gradually from amorphous to crystalline phase with temperature. When heat treated at 300 °C for 2h, RuO2·n H2O electrode surface gains mass of2.5 mg/cm2 with specific capacitance of 782 F/g. Besides, it is found that the specific capacitance of the film decreased by roughly20% with voltage scan rate increasing from 5 to 250 m V/s.

Fabrication Process of Sol-Gel Spin Coating for SrBi2Ta2O9 Films Applied to FeRAM

We investigate SrBi2 Ta2 O9 （SBT） films prepared by the sol-gel spin method with different spin rates or different anneal conditions for the first layer of SBT, as promising ferroelectric layer materials applied to ferroelectric random access memory （FeRAM）. All the specimens in this experiment have similar SBT crystal orientations of （115）, （020）, （220）, and （135）. The Pt/SBT/Pt capacitor with coating of 3000rpm spin rate has a perfect rectangle shape of hysteresis loops, remanent polarization of 7.571μC/cm^2 and coercive voltage of 0.816 V at 5 V voltage amplitude. These characteristics are better than those with coating of 3500rpm spin rate, which is attributed to the influence for thickness and grain size of the film from depressed spin rate. Slow-rate anneal in the furnace for the first layer of SBT can improve the crystallization processes and properties for SBT layers slightly, compared with rapid thermal annealing. The ion damage from etching for the top electrode can influence leakage current characteristics of the Pt/SBT/Pt capacitor at positive voltage bias.

Fabrication and Characterization of Semi-Crystalline and Amorphous Dielectric Polymer Films for Energy Storage

Dielectric polymer films are energy storage materials that are used in pulse power operations, power electronics and sustainable energy applications. This paper reviews energy storage devices with focus on dielectric film capacitors. Two prominent examples of polymer dielectrics Polyetherimide (PEI) and Poly (tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride) (THV) have been discussed. Polyetherimide (PEI) is an amorphous polymer recognized for its high-temperature capability, low dielectric loss and high dielectric strength. THV is a semi-crystalline polymer with high dielectric constant, high-temperature capability and charge-discharge efficiency. The primary focus of this paper is to introduce the reader to the fabrication procedures and characterization techniques used in research labs for processing of dielectric polymers. The fabrication and characterization process of both polymers has been discussed in detail to shed the light on experimental process in this area of research.

基于电介质薄膜的器件自愈性能的研究现状

随着能源与电力技术的不断发展,对电容器的需求越来越大,而各种资源的稀缺强调了利用各种能源的必要性,对于各种储能器件如金属化薄膜电容器以及基于电活性聚合物(electroactive polymers,EAP)的能量转换装置提出了更高的要求。然而这两类装置却极易发生电击穿,在工作循环中有着极高的故障率,因此器件的自愈性具有十分重要的意义。文中综述了金属化薄膜电容器和EAP能量转换装置自愈性能的国内外研究现状,首先重点关注了金属化薄膜电容器中自愈理论发展以及各种关键参数对自愈的影响,其自愈最为稳定且研究相对完善。随着介电弹性体的兴起,想要其拥有自愈性能,参考金属化薄膜电容器的结构是一个可行的思路。但如何使得金属电极满足大应力大形变的需求成为一种柔性电极是一个很大的挑战。碳电极是弹性体中应用最为广泛的电极材料,它拥有极好的形变能力,但对于其自愈性能的深入研究较少且缺乏成熟的理论支撑,使得其在工业领域中难以应用和改善。最后总结对比了金属电极以及碳电极在自愈性能上的差异,并预测了可自愈柔性电极新的发展方向,进一步拓展自愈性的器件在工业领域中的应用。

电容器用双向拉伸聚4-甲基-1-戊烯(BOPMP)薄膜开发与应用

聚4-甲基-1-戊烯(PMP)是一种具有等规结构的新型热塑性塑料,PMP为结晶性树脂,熔点在235℃~240℃之间,耐热性好,可在高温下使用,并具有卓越的电气绝缘和介电性能。与聚丙烯树脂相比,熔点高60℃,介电常数、介电损耗相近。随着我国电子工业的发展,PMP的用量在近年来有大幅的增长。目前世界上只有日本三井化学株式会社生产,由于产量有限、售价较高,限制了PMP在国内的应用。为此本文尝试采用双向拉伸的方法,试制聚4-甲基-1-戊烯(BOPMP)薄膜,并加工成金属化膜,试制电容器,最后对电容器的性能进行相应测试评价。采用不同牌号原料生产BOPMP薄膜,其电压击穿强度差别较大,不同频率下的BOPMP薄膜电容器损耗角正切值、介电常数均与BOPP薄膜电容器接近,但其高温下的性能有待进一步验证。如何提升BOPMP薄膜电压击穿强度及其耐热性,开发出适宜于双向拉伸的PMP粒子原料,生产出高质量的BOPMP电容薄膜,将是未来重点研究的方向。

薄膜电容器数据挖掘与分析

作为电力系统的重要元件之一,薄膜电容器因长使用寿命、高可靠性等优点而受到广泛应用,然而却极少有研究从数据角度挖掘电容器的自身属性。为了填补这一空白,本文选取收集自网络的40793条薄膜电容器数据作为分析基础,首先利用散点图和箱线图从横向角度分析了不同材料制备而成的电容器的容值、最高最低温度、交直流运行电压等差异,然后利用饼图从纵向角度对比了电容器的运行温度和应用场合,最后计算出这些性能指标的皮尔逊系数并进行了相关性分析。结果表明金属化聚丙烯材料作为目前的主流材料在容值和交直流运行电压方面比其他材料均具有显著的优势,而金属化聚苯硫醚在运行温度上占优,电容器除温度和运行电压外的各项参数之间的相关性并不显著。未来可以进一步对数据进行处理和学习,达到性能预测的效果。

干式直流电容器全链条国产化关键技术探讨

高性能薄膜电容器广泛应用于新能源交通工具、输变电工程、医疗救治器械和电磁脉冲武器等领域,其中干式直流电容器更是柔性直流输电的重要装备。目前薄膜电容器生产过程中从原料到重要装备完全依靠国外技术,高端薄膜电容器超净聚丙烯(PP)原料完全依赖从国外进口,加工双向拉伸BOPP薄膜和电极蒸镀等大型生产设备都是从发达国家购买,严重制约了我国薄膜电容器技术研发和工程应用,特别是在当前的复杂国际环境下带来诸多隐患,一旦国外禁止向我国出售相关原料和设备,将严重影响我国高科技领域的发展。由此,在当前复杂的国际环境和我国政府提出的“双碳”目标背景下,必须下大力气着力解决影响薄膜电容器领域发展的诸多关键因素,依靠自主技术服务于新能源系统建设。在国家重点研发计划“干式直流电容器用电介质薄膜材料”重点专项支持下,本文从薄膜电容器用电工级超净PP原料入手,探讨通过相关领域科研院所与相关企业深度合作,进行电工级超净PP原料技术攻关,解决研发验证过程中存在的问题,从全局观出发力图解决我国干式直流电容器工程应用面临的重大问题,形成我国干式直流电容器全链条国产化关键技术。

接枝聚丙烯电容薄膜的高温储能特性

随着海上风电、电动汽车和油气勘探的迅速发展,对薄膜电容器的工作温度提出更高的要求。然而,当环境温度达到120℃时,目前使用最为广泛的双向拉伸聚丙烯电容薄膜充放电效率急剧下降,不能满足应用需求。该文制备了苯乙烯接枝聚丙烯(PP-g-St)双向拉伸电介质薄膜,在120℃下,PP-g-St可以将能量密度从0.23 J/cm^(3)提高到1.67 J/cm^(3)(储能效率在90%以上),同时接枝后击穿场强大幅提升,高温泄漏电流得到有效抑制,这源自于接枝后引入的深陷阱限制了载流子的输运。接枝样品中的自聚相经拉伸后与基体具有良好的相容性。该文研究为适用于高温高场条件的聚丙烯基电容器薄膜材料的大规模制备提供可能。

电容器用超净聚丙烯薄膜综合性能比较

研究了不同聚丙烯粒料、不同薄膜生产厂家制备的一系列电容器用超净聚丙烯薄膜的主要性能指标;对比了不同聚丙烯粒子制备电容器膜的结晶特性、热性能、介电性能和绝缘性能等各项性能差异。测试结果表明,部分国产电容器用聚丙烯薄膜性能已达到进口薄膜标准,但仍存在国产膜结晶度偏低、薄型膜质量较差的问题。国产电容器用聚丙烯薄膜距离世界领先水平仍有差距,需要进一步提高国产粒料性能,优化薄膜制备工艺。

金属化薄膜电容器介电薄膜材料的研究现状

近年来,随着新能源汽车和柔性直流输电工程等领域的迅速发展,对高容积比、耐高温金属化薄膜电容器的需求日益增加,尤其对高温高电场等极端条件下电容器中介电薄膜的电气性能提出了更高要求。本文总结了近年来金属化薄膜电容器介电薄膜材料的研究现状和发展趋势。首先,介绍影响介质薄膜储能性能的关键因素,并分析金属化薄膜电容器在运行工况下的失效原因;其次,归纳基于分子链结构、聚集态结构、功能填料掺杂和表面改性等4个方面设计的介电薄膜储能性能改性方法;最后,对提升金属化薄膜电容器介电薄膜的储能性能的策略进行总结并做出展望。

基于金属化薄膜电容器状态在线监测的剩余寿命评估方法

模块化多电平变流器(MMC)是柔性直流输电系统的核心装备,其中子模块(SM)金属化薄膜电容器是MMC中的薄弱环节之一,故研究金属化薄膜电容器的状态监测和寿命评估对于提高MMC运行可靠性和制定系统维护计划具有重要意义。目前,现有金属化薄膜电容器的寿命评估方法未考虑电容器老化进程对电容值和等效串联电阻(ESR)的影响,难以准确实现不同服役状态下的电容器剩余寿命评估问题。因此,该文提出考虑当前电容值状态在线监测的金属化薄膜电容器的剩余寿命评估方法。首先,在考虑电容器老化速率与温度耦合关系的基础上建立了电容器ESR和电容值的老化模型。其次,在进行寿命计算时考虑到电容器的老化效应,根据提出的容值在线监测方法得到当前的电容值,推断出电容器已使用年限及电容器目前的ESR值,并代入建立的场路协同仿真电热耦合模型中计算得到电容器温度。最后,根据提出的剩余寿命模型对电容器当前剩余寿命进行预测。该文研究成果将为设备选型、系统设计和MMC系统子模块电容器的可靠性评估提供参考。

全膜脉冲电容器电热老化分析

全膜脉冲电容器是脉冲功率系统的重要储能单元,其寿命影响着整个系统的可靠性。在脉冲工况下,全膜脉冲电容器的失效多为突发失效,且寿命的分散性较大。为探究全膜脉冲电容器老化失效机理,开展了其寿命试验及电场与温度场的仿真。利用LTD基本放电单元(Brick)实验腔体对电容器进行寿命测试并获得失效电容器,分析了失效电容在不同故障形式下的失效原因,并利用有限元分析软件对电容器局部“电场易畸变”区域进行了电场仿真,说明上述区域存在的畸变电场是发生绝缘介质击穿的主要原因;对电容器进行温度场分析,发现电容器温度与充放电频率成正相关,温度最高点位于电容器几何中心处附近,在充放电频率较低时,电容器温升不明显,说明在较低充放电频率下,电容器绝缘介质老化以电老化为主,而非热老化。

金属化聚丙烯膜电容器自愈产气特性与保护技术

金属化膜电容器由于其自愈特性具有较高的工作场强和可靠性,但电容器在自愈过程中会产生大量气体,严重影响电容器运行的可靠性。文中以金属化聚丙烯膜电容器元件为研究对象,分析了自愈产气量与电容量损失的关系,计算了压力保护的动作阈值,采用气相色谱法测量了电容器自愈产生的气体成分,并基于氢敏传感器对电容器在密闭环境中的产气特性进行了研究。研究结果表明,自愈过程的产气体积与其电容量损失近似成线性关系;金属化聚丙烯膜电容器自愈所产生的气体主要包含H_(2)、C_(2)H_(2)、CH_(4)和CO,并且自愈还会产生无定型碳单质;电容器持续自愈过程中密闭环境中的氢气体积分数与加压时间成正比,当电容器发生短路故障时,氢气体积分数会迅速增大,使用氢敏传感装置可以准确的检测到这种现象。

谐波环境下模块化多电平换流器子模块电容器的多场耦合分析及优化研究

金属化薄膜电容器作为柔性直流输电用换流阀的核心设备,在大谐波分量与高环境温度的复杂多物理场作用下存在异常温升、鼓包形变等问题,严重影响着电容器的使用寿命。该文建立了金属化薄膜、电容器单体与电容器整机的电-热-力多场耦合模型,分析了模块化多电平换流器子模块常见谐波环境下,电容器内部多物理场特性。发现谐波电流增强了电容器层间电场畸变与金属化层的欧姆损耗,谐波电场的叠加增大了基膜的介质损耗,综合导致了电容热点温度与内部应力值在谐波分量的增大下呈指数形式上升。为改善电容器在谐波环境下的运行稳定性,采用多目标粒子群算法对单体电容的结构参数进行了优化,得到了单体结构最优解:膜厚4.7mm,膜宽41.8mm,电容直径40.6mm。优化后电容器内部电场畸变系数、热点温度与最大应力值分别降低了23%、22%与31%。提高了电容器在谐波环境下的工作性能,对提升其运行可靠性有一定的指导意义。

电容器薄膜用聚丙烯原料微量元素分析方法

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