Dielectric Breakdown Performance Research Articles

Linking traps to dielectric breakdown through charge dynamics for polymer nanocomposites

Polymer nanocomposites can change the density and/or energy of traps, suppress the accumulation of space charges, and enhance dielectric breakdown strength. It is of interest to reveal the influencing mechanism of trap properties on the dielectric breakdown of polymer nanocomposites. Results of thermally stimulated depolarization current and surface potential decay were reviewed, showing that incorporating a small amount of nanoparticles into a polymer can increase the density and/or energy of deep traps. Then, the relation between traps and dc breakdown field of several polymer nanocomposites were analyzed. It was found that the increase in the density and energy of deep traps contributes to the improved dielectric breakdown performance. The modifications of traps by nanoparticles and surface treatments affect the charge dynamics in the bulk of polymer nanocomposites. Then, the accumulation of space charges, the distortion of electric field, and the energy gain of free carriers are regulated to improve the performance of dielectric breakdown.

Experimental investigations into the enhanced dielectric breakdown performances of propylene carbonate modified by TiO2nano-particles

Water is frequently used as energy storage medium in the compact pulsed power system because of its great dielectric constant and high breakdown strength. As an alternative to water, propylene carbonate (PC) has relatively low freezing temperature and large resistivity. In this study, TiO2 nano-particles with different volume concentrations have been suspended into PC to enhance the dielectric strength. Breakdown voltage and the time lag to breakdown with several tens microseconds’ duration have been investigated for PC and PC-based nano-fluids. The waveforms of breakdown voltages were measured by a calibrated voltage divider. Experimental results show that, with increasing the value of high-voltage electrode potential increasing rate, the breakdown strength increases and the time lag to breakdown decreases. Experimental results also show that, the dielectric properties of nano-fluids are strongly influenced by the volume percents of the nano-particles. In general, the addition of nano-particles is favorable for the overall dielectric performance of PC. For a large high-voltage electrode potential increasing rate, the mean breakdown voltage of nano-fluids is largely increased compared with that of PC; for a low high-voltage electrode potential increasing rate, the breakdown voltage increases and the scatter of breakdown data decreases, which shows a great potential to increase the reliability of the pulsed power system.

Enhanced dielectric breakdown performances of propylene carbonate modified by nano-particles under microsecond pulses

Propylene carbonate shows appealing prospects as an energy storage medium in the compact pulsed power sources because of its large permittivity, high dielectric strength, and broad operating temperature range. In this paper, TiO2 nano-particles coated with γ-aminopropyltriethoxylsilane coupling agent are homogeneously dispersed into propylene carbonate and these nano-fluids (NFs) exhibit substantially larger breakdown voltages than those of pure propylene carbonate. It is proposed that interfaces between nano-fillers and propylene carbonate matrix may provide myriad trap sites for charge carriers. The charge carriers can be easily captured at the interfaces between NFs and the electrode, resulting in an increased barrier height and suppressed charge carriers injection, and in the bulk of NFs, the charge carriers' mean free path can be greatly shortened by the scattering effect. As a result, in order for charge carriers acquiring enough energy to generate a region of low density (the bubble) and initiate breakdown in NFs, much higher applied field is needed.

Large-area dielectric breakdown performance of polymer films – Part II: Interdependence of filler content, processing and breakdown performance in polypropylene-silica nanocomposites

In this study, large-area dielectric breakdown performances of various bi-axially oriented polypropylene (BOPP)-silica nanocomposite films are studied by utilizing the self-healing multi-breakdown method presented in the Part I of this publication. In particular, the effects of silica filler content, pre-mixing method, co-stabilizer content and film processing on the large-area breakdown performance are analyzed. Nanostructural and film cross-sectional analyses are correlated to the breakdown responses. The optimum silica filler content is found to reside at the low fill fraction level (~1 wt-%) and automatic pre-mixing of the raw materials and the optimization of the orientation temperature are found to be preferable. The co-stabilizer Irgafos 168 is found to have a significant effect on the breakdown distribution homogeneity of the reference BOPP films. The breakdown response of the silica nanocomposites is found to be not only dependent on the active measurement area but also on the voltage ramp rate, indicating that the silica nanocomposites exhibit altered internal charge behavior under DC electric field. The area- and ramp-rate-dependence results exemplify the importance of careful breakdown strength evaluation of dielectric polymer nanocomposites. Above all, the results emphasize the fact that a thorough understanding and the optimization of the film processing parameters are crucial for achieving improved breakdown response in dielectric polymer nanocomposite films.

Highly Robust Advanced Single Precursor Based k 2.4 ILD for Beol Cu Interconnects

Continuous shrinking of the interconnect dimensions with each technology node requires reduction in RC (resistance-capacitance) delays. Reduction in capacitance requirement at 45nm node was met by introducing a k 2.4 inter-layer dielectric (ILD) at 2X metallization level [1]. However, the material was not readily extendable to next technology node because of the need for even higher modulus at the advanced nodes. Thus, there was a need to develop a new pSiCOH k 2.4 ILD with improved mechanical properties and damage susceptibility for back end of the line (BEOL) capacitance reduction. IBM/Alliance team has developed a number of pSiCOH films using a variety of precursors. Generally, the porous ultra-low k films are prepared by using a subtractive approach [2] in which the film is deposited using a mixture of skeleton and porogen precursor and then cured to remove the labile organic fraction [2]. An alternative to the above approach is to use a single precursor molecule consisting of skeleton with embedded porogen [3]. Developing a robust pSiCOH film with k < 2.55 has always been a challenge with this approach. This paper reports the development of a pSiCOH k 2.4 film deposited using a single precursor showing superior time dependent dielectric breakdown (TDDB) performance with lower integrated k (lower capacitance) as compared to the k 2.55 ILD pSiCOH film at 80 nm, 56 nm and 48 nm pitch. Octamethylcyclotetrasiloxane (OMCTS) precursor used for fabricating dense SiCOH dielectrics (k= 3.0-2.7) was used to form low k=2.4 film. The modified PECVD deposition conditions along with optimized UV cure resulted in k 2.4 ILD film deposited using a single precursor henceforth referred to as OMCTS Ex k 2.4. The new OMCTS Ex k 2.4 film has only slightly lower modulus as compared to the k 2.7 film deposited using OMCTS and O2 while showing comparable plasma induced damage (PID). PID was measured by thickness change after HF wet etch removed the damaged layer caused by standard plasma. In general, good TDDB performance is obtained by lowering porosity, increasing %C and reducing PID [4]. Each of these properties has been carefully optimized for new OMCTS Ex k 2.4 film by tuning the deposition and the UV cure conditions. Fig. 1 compares the RC performance for ULK k 2.55, ULK A k 2.4 (another PECVD k2.4 ILD) and OMCTS Ex k 2.4 film at 10 nm node. ULK A k 2.4 shows higher PID as compared to k 2.55 resulting in higher capacitance. In contrast, the OMCTS Ex k 2.4 retains the capacitance benefit because of the lower PID for this film. Table 1 compares the extracted k value for k 2.55 and the k 2.4 ILD’s at 80, 56 and 48 nm pitch. OMCTS Ex continues to show lower extracted k number with no significant increase in value with technology node scaling. Fig. 2 shows the TDDB performance of these ILD’s at 10 nm node. The higher carbon content with low plasma induced damage resulted in dramatically better TDDB for OMCTS Ex than other films. Important to note that the TDDB performance of this film is almost 15X better than the TDDB performance of k 2.55 and ULK A k 2.4 ILD. Conclusion A new advanced single precursor OMCTS Ex k 2.4 pSiCOH ILD film has been developed to meet the integration scaling and reliability requirements. The new OMCTS Ex k 2.4 film shows better film properties than the reference k 2.55 and other 2.4 films and retains capacitance benefit by demonstrating an overall lower integrated k value as compared to the k 2.55 ILD. Acknowledgement This work was performed by the Research and Development Alliance Teams at various IBM Research and Development Facilities.

Large-area dielectric breakdown performance of polymer films - part i: measurement method evaluation and statistical considerations on area-dependence

A multi-breakdown measurement method for large-area dielectric breakdown characterization of polymer films is presented and evaluated. Based on the self-healing breakdown capability of metalized film, large amount of breakdown data can be obtained from a relatively large total film area, thus enabling the execution of detailed breakdown performance analysis. The studied films include non-metalized laboratoryscale, pilot-scale and commercial capacitor-grade bi-axially oriented polypropylene films in the thickness range of 14-25 μm. With the active measurement area of 81 cm2 per sample, breakdown distributions covering total film areas of 486-972 cm2 are presented. Various aspects encompassing the sample film preparation, measurement procedure, breakdown progression, discharge event characterization, breakdown field determination, data validation and statistical analysis are discussed. Comparative small-area breakdown measurements were performed in order to study the relationship between the large-area multi-breakdown measurement method and a conventional small-area (1 cm2) manual breakdown measurement method. Implications of the areadependence and the applicability of the Weibull area-scaling are also discussed.

Dielectric breakdown properties of hot SF6 gas contaminated by copper at temperatures of 300–3500 K

The dielectric breakdown properties of hot SF6 gas during the dielectric recovery phase play an important role in understanding gas breakdown occurring in high-voltage circuit breakers. This paper is devoted to the theoretical investigation of dielectric breakdown properties of hot SF6 gas contaminated by copper at temperatures of 300–3500 K and pressures of 0.01–1.6 MPa. The equilibrium compositions of SF6–Cu mixtures are obtained with the consideration of condensed species. The unknown ionization cross sections for CuS, CuF and CuF2 are calculated using a Deutsch–Märk (DM) formalism based on quantum chemistry. The two-term Boltzmann equation is adopted to numerically calculate the electron energy distribution function, collision ionization coefficient and electron attachment coefficient. Then the reduced critical electric field strength is determined when the effective ionization coefficient equals to zero. The influences of the Cu proportion and gas pressure on the dielectric breakdown properties are investigated. It is shown that the existence of copper compounds increases the concentration of high-energy electrons significantly, even for the case with a very low percentage (e.g. 1% Cu). With the increase of copper content, the value of (E/N)cr is reduced remarkably at temperatures below 3000 K, but enhanced slightly above 3000 K. It is also found that the increase of pressure can improve the dielectric breakdown performance of hot SF6–Cu mixtures.

Effect of crystallization temperature on the dielectric property and energy density of SrO–BaO–Nb2O6–B2O3 glass–ceramics

A SrO–BaO–Nb2O6–B2O3 glass–ceramic was prepared by controlled-crystallization method, and the phase evolution and dielectric properties were investigated. The correlation between the dielectric breakdown performance and the activation energy was studied by the measurements of the dielectric breakdown strength and impedance spectroscopy as a function of crystallization temperature in a SrO–BaO–Nb2O6–B2O3 glass–ceramics. It was found that dielectric breakdown strength strongly depended on the interface polarization. The crystallization temperature dependence of breakdown strength was attributed to the variation in interfacial polarization based on the results of impedance analysis. The prepared glass–ceramic crystallized at 800°C exhibited a breakdown strength of 1050kV/cm, a dielectric constant of 117 and a high energy storage density of 5.71J/cm3.

Dielectric properties and charge–discharge behaviors in niobate glass ceramics for energy-storage applications

A series of niobate glass ceramics with varying glass content have been prepared via controlled-crystallization route, and the dielectric properties, the breakdown characteristics and charge–discharge behaviors have been investigated. The correlation between the dielectric breakdown performance and the activation energy was studied by the measurements of the dielectric breakdown strength and impedance spectroscopy. The charge–discharge efficiency was investigated using a charge–discharge system with high-speed capacitor discharge circuit device. It was found that the dielectric breakdown strength and the discharge efficiency strongly depend on the interface polarization based on the results of complex impedance analysis. With the increase of the glass content, the breakdown strength (BDS) and the charge–discharge efficiency show a clear increasing trend, when the content of glass was 60%, the typical G60 sample shows a high BDS of 1300kV/cm and a high charge–discharge efficiency of 92.5%.

Dielectric breakdown properties of hot SF6-CO2 mixtures at temperatures of 300–3500 K and pressures of 0.01–1.0 MPa

Recently, much attention has been paid to SF6-CO2 mixtures as one of substitutes for pure SF6 gas. In this paper, the dielectric breakdown properties of hot SF6-CO2 mixtures are investigated at temperatures of 300–3500 K and pressures of 0.01–1.0 MPa. Under the assumptions of local thermodynamic equilibrium and local chemical equilibrium, the equilibrium compositions of hot SF6-CO2 mixtures with different CO2 proportions are obtained based on Gibbs free energy minimization. The cross sections for interactions between electrons and neutral species are presented. Some unknown ionization cross sections are determined theoretically using Deutsch–Märk (DM) formalism based on quantum chemistry. Two-term Boltzmann equation is adopted to calculate the electron energy distribution function, reduced ionization coefficient, reduced attachment coefficient, and reduced effective ionization coefficient. Then the reduced critical electric field strength of mixtures, corresponding to dielectric breakdown performances, is determined when the generation and loss of electrons are balanced. Finally, the influences of temperature, pressure, and CO2 proportion on the reduced critical electric field strength are studied. It is found that a large percentage of CO2 can obviously reduce concentrations of high-energy electrons. At temperatures above 1750 K, an addition of CO2 to SF6 gas can enhance dielectric breakdown performances. However, at low temperatures, too much CO2 added into mixtures can reduce dielectric breakdown abilities. In addition, increasing gas pressure can improve dielectric breakdown performances. But the influence will be no more significant if pressure is over 0.8 MPa.

Effect of the Ba/Na ratio on the microstructure and dielectric properties of (BaO, Na2O)–Nb2O5–SiO2 glass–ceramics

A series of (BaO, Na2O)–Nb2O5–SiO2 glass–ceramics with a varying ratio of Ba/Na have been prepared via controlled-crystallization route, and the phase evolution, and dielectric properties have been investigated. The correlation between the dielectric breakdown performance and the activation energy was studied by the measurements of the dielectric breakdown strength and impedance spectroscopy. It was found that the change in the Ba/Na ratio in the glass notably modified the dielectric properties. The increase of Ba/Na ratio promoted the crystallization of Ba2NaNb5O15 from the glass matrix that has a high dielectric constant. When the ratio of Ba/Na was 2, the optimization of dielectric breakdown performance and dielectric constant was obtained. The as-devitrified (4BaO, Na2O)–Nb2O5–SiO2 glass–ceramic exhibits a large dielectric breakdown strength of 864kV/cm with a stable dielectric constant of about 150 over the temperature range of −50°C to 100°C.

Dielectric relaxation behavior and energy storage properties in Ba 0.4 Sr 0.6 Zr 0.15 Ti 0.85 O 3 ceramics with glass additives

Abstract Ba 0.4 Sr 0.6 Zr 0.15 Ti 0.85 O 3 ceramics with SrO–B 2 O 3 –SiO 2 glass additives were prepared via the solid state reaction route. The effects of glass contents on the sintering behavior, dielectric properties, microstructures, and energy storage properties of BSZT ceramics were investigated. Dielectric breakdown strength of 22.4 kV/mm was achieved for BSZT ceramics with 20 wt% glass addition. Dielectric relaxation behavior was observed in dielectric loss versus temperature plots. In order to investigate the mechanism of dielectric breakdown performance, the relationship between dielectric breakdown strength and grain boundary barrier was studied by the measurements of breakdown strength and activation energy. A discharged energy density of 0.45 J/cm 3 with an energy efficiency of 88.2% was achieved for BSZT ceramics with 5 wt% glass addition.

Effect of thermal conductivity on tracking failure of Epoxy/BN composite under pulse strength

Epoxy (EX) is widely used as insulating materials in electric devices with its excellent insulating properties in spite of its weak ability of thermal conduction. One possible way to obtain high thermal conductivity for Epoxy is the use of an inorganic filling material. Tracking failure is a typical dielectric breakdown performance on polymer surface. Thermal conductivity is associated with the tracking failure performance. In this paper, it is attempted to clarify whether the addition of Boron Nitride (BN) particles can achieve the aim of improving resistance to tracking failure of Epoxy by the way of increasing its thermal conductivity. Prior to test, samples were prepared by dispersing BN particles into EX with shear force. Tracking failure tests were performed at room temperature. The thermal conductivity effects on the time to tracking failure, the discharge quantity of discharge current and the thermal photographs were discussed. Obtained results show that with increasing the concentration of BN particles, the maximum temperature and the discharge quantity decrease, but the time to tracking failure increases. The experimental results suggest that the concentration of BN particles plays a main role in the result of the tracking failure. The resistance to tracking is improved by the filler of BN particles, which is due to the improvement of thermal conductivity.

Dielectric breakdown performance of alumina/epoxy resin nanocomposites under high voltage application

Epoxy/alumina nanocomposites were prepared by reducing micron size alumina into nanosize during the casting process. In our current investigation it was found that, at low concentration alumina nanoparticles exhibit uniform dispersion of alumina nanoparticles in epoxy nanocomposite while at higher concentration they depict aggregation of alumina particle. Since uniform dispersion of alumina nanoparticles results in improved thermal stability and viscoelastic behavior. It leads to remarkable improvement in breakdown voltage, and breakdown time of epoxy/alumina nanocomposites as compared to neat epoxy. Epoxy nanocomposites containing 2wt.% of alumina particles results in increase of breakdown voltage by 91% and breakdown time by 155% as compared to neat epoxy. Hence, the nanocomposites developed can be used as insulating material in electrical instruments which require high breakdown voltage as well as improved viscoelastic behavior and thermal stability.

Characterization of Electron Traps in Si-Capped Ge MOSFETs With $\hbox{HfO}_{2}/\hbox{SiO}_{2}$ Gate Stack

Si-capped Ge MOSFETs have good compatibility with existing processes, and promising results have been reported. The process is becoming sufficiently mature to warrant assessment of device reliability. Good time-dependent dielectric breakdown performance has been observed, and negative-bias-temperature-instability susceptibility is better than Si counterparts. Electron trapping is shown to be problematic and affects devices through positive bias temperature instability and hot carrier injection. This letter characterizes electron trapping in HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> stacks on Si-capped Ge. Trapping is substantial, increasing with <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">VG</i> and reaching ~ 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> in 100 μs under <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">VG</i> = 2.0 V. We report, for the first time, two distinctive capture cross sections (CCS) by measuring the transient gate current. The large CCS can be ~ 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-12</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and reduces for a higher oxide field, which is a signature of coulombic attractive centers. The small CCS is on the order of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-14</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , which is a typical value found for electron traps in SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> stacks on Si.

The increased dielectric breakdown voltage of transformer oil-based nanofluids by an external magnetic field

In this study, we have measured the dielectric breakdown voltage of transformer oil-based nanofluids in accordance with IEC 156 standard and have investigated the dielectric breakdown performance with the application of an external magnetic field and different volume concentrations of magnetic nanoparticles. It was confirmed that the dielectric breakdown voltage of pure transformer oil is about 10 kV with a gap distance of 1 mm between electrodes. In the case of our transformer oil-based nanofluids with 0.08% < Φ < 0.39% (Φ means the volume concentration of magnetic nanoparticles in the fluid), the dielectric breakdown voltage was three times higher than that of pure transformer oil. Furthermore, when the external magnetic field was applied under the experimental vessel, the dielectric breakdown voltage of the nanofluids was above 40 kV, which was 30% higher than that without the external magnetic field.

Experimental Study on the Dielectric Breakdown Voltage of the Insulating Oil Mixed with Magnetic Nanoparticles

Abstract In this study, we have measured the dielectric breakdown voltage of transformer oil-based nanofluids in accordance with IEC 156 standard and have investigated the dielectric breakdown performance with the application of an external magnetic field and different volume concentrations of magnetic nanoparticles. It is confirmed that the dielectric breakdown voltage of pure transformer oil is about 10 kV with a gap distance of 1 mm between electrodes. In the case of our transformer oil-based nanofluids with 0.08%

Development of epoxy/BN composites with high thermal conductivity and sufficient dielectric breakdown strength part II-breakdown strength

The aim of this research is to find a way to achieve the epoxy composites with high thermal conductivity and acceptable dielectric breakdown (BD) strength. A value 12.3 W/m·K is the highest thermal conductivity obtained for epoxy composite in Part I. Dielectric breakdown performances such as short-time dielectric breakdown strength (BD strength), partial discharge (PD) resistance and BD time for composites were investigated in the Part II. In general, micro filler inclusion will increase thermal conductivity and decrease dielectric breakdown performance. Influencing factors are considered to be the orientation of filler, the content of void space, the content ratio in the case of co-mixing, the addition of nano filler, and filler surface modification. Twenty six kinds of composites were prepared in consideration of the above influencing factors. There are two options for most appropriate ones among the composites evaluated in the research. One is an epoxy/ conglomerated h-BN composite with co-loaded nano SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and micro AIN filler. It has 12.3 W/m·K in thermal conductivity, 75.1 kV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">peak</sub> /mm in BD strength and 260 % of BD time for neat epoxy. It is most suitable when low BD strength and high thermal conductivity is needed. The other one is an epoxy/ h-BN composite with co-loaded nano silica and AIN filler for requirement of very high BD strength but lower thermal conductivity. Optimum thermal conductivity is obtained if flaky h-BN filler is oriented in parallel to heat flow. Since it is difficult to realize full orientation, the use of conglomerated h-BN filler is a suitable option. Optimum BD performance is obtained if void space is reduced by certain methods such as co-dispersion of different size fillers and addition of nano filler.

Design of the corona current measurement sensor with wide bandwidth under dc ultra-high-voltage environment

The research in the field of corona discharge, which is one of the key technologies, can help us to realize ultra-high-voltage (UHV) power transmission. This paper proposes a new sampling resistance sensor to measure the dc UHV corona current in a wide band. By designing the structural and distributed parameters of the sensor, the UHV dielectric breakdown performance and the wide-band measuring characteristics of the sensor are satisfied. A high-voltage discharge test shows that the designed sensor can work under a 1200 kV dc environment without the occurrence of corona discharge. A frequency characteristic test shows that the measuring bandwidth of the sensor can be improved from the current 4.5 to 20 MHz. The test results in an actual dc UHV transmission line demonstrate that the sensor can accurately measure the corona current under the dc UHV environment.

Improved polymer nanocomposite dielectric breakdown performance through barium titanate to epoxy interface control

Abstract A composite approach to dielectric design has the potential to provide improved permittivity as well as high breakdown strength and thus afford greater electrical energy storage density. Interfacial coupling is an effective approach to improve the polymer-particle composite dielectric film resistance to charge flow and dielectric breakdown. A bi-functional interfacial coupling agent added to the inorganic oxide particles’ surface assists dispersion into the thermosetting epoxy polymer matrix and upon composite cure reacts covalently with the polymer matrix. The composite then retains the glass transition temperature of pure polymer, provides a reduced Maxwell–Wagner relaxation of the polymer-particle composite, and attains a reduced sensitivity to dielectric breakdown compared to particle epoxy composites that lack interfacial coupling between the composite filler and polymer matrix. Besides an improved permittivity, the breakdown strength and thus energy density of a covalent interface nanoparticle barium titanate in epoxy composite dielectric film, at a 5 vol.% particle concentration, was significantly improved compared to a pure polymer dielectric film. The interfacially bonded, dielectric composite film had a permittivity ∼6.3 and at a 30 μm thickness achieved a calculated energy density of 4.6 J/cm3.