High Insulation Resistance Research Articles

Comparative study on the effect of electron beam irradiation on the physical properties of ethylene-vinyl acetate copolymer composites

Ethylene-vinyl acetate copolymer (EVA) flame retarded by a combination of cellulose acetate butyrate (CAB) microencapsulated ammonium polyphosphate (MCAPP) and polyamide-6 (PA-6) have been crosslinked by high energy electron beam irradiation. The effect of high energy electron beam irradiation on the crosslinking degree, mechanical, electrical and thermal properties of EVA/MCAPP/PA-6 cable material was studied by gel content, heat extention test, mechanical test, dynamic mechanical analysis, high-insulation resistance meter and thermogravimetric analysis. The gel content and heat extention test results showed that the EVA/MCAPP/PA-6 composites can be easily crosslinked by electron beam irradiation. The tensile strength of EVA composites was drastically increased from 16.2 to maximum 26.2MPa as the electron beam irradiation dose increases from 0 to 160kGy. The volatilized products of EVA/MCAPP/PA-6 composites were analyzed and compared by thermogravimetric analysis/infrared spectrometry (TG-FTIR).

Enhanced thermal and electrical properties of poly (D,L-lactide)/multi-walled carbon nanotubes composites by in-situ polymerization

Biodegradable poly (D,L-lactide) (PLA)/carboxyl-functionalized multi-walled carbon nanotubes (c-MWCNTs) composites were achieved via in-situ polymerization. These as-prepared composite materials were characterized with FT-IR, XRD, TG, DSC, SEM, and high insulation resistance meter. The results demonstrate that the multi-walled carbon nanotube was carboxyl functionalized, which improved the collection between c-MWCNTs and PLA, and further realized the graft copolymerization of c-MWCNTs and PLA. There is a higher glass transition temperature and a lower pyrolysis temperature of PLA/c-MWCNTs composites than pure PLA. The c-MWCNTs gave a better dispersion than unmodified MWCNTs in the PLA matrix, and an even coating of PLA on the surface of c-MWCNTs was obtained, which increased the interfacial interaction. High insulation resistance analysis showed that the addition of c-MWCNTs increased the electric conductivity, and c-MWCNTs performed against the large dielectric coefficient and electrostatic state of PLA. These results demonstrated that c-MWCNTs modified PLA composites were beneficial for potential application in the development of heat-resisting and conductivity plastic engineering.

KEMET SMD Film Capacitors for High Temperature Applications

Trends of several applications like down-hole drilling, commercial aviation (e.g. jet engines), heavy industrial and automotive are challenging the capabilities of capacitors and other electronic components. The growing harsh-environment conditions for these applications are: high temperature, high voltage and high current. At the capacitor component level, required features are: very high reliability under mechanical shock, rapid changes in temperature, low leakage current (high insulation resistance), small dimensions, good stability with time and humidity, and high peak withstanding voltage. Capacitors for power-conversion circuitry must maintain a low AC loss and DC leakage at high temperatures. KEMET has recently designed film capacitor series using PEN to address the needs of the above mentioned circuits, in particular regarding the working temperature, voltage and current. This paper will cover technological advances in film capacitor technology to address harsh environment conditions needs, providing test results on temperature, voltage and thermal shock acceleration factor.

Silicon Capacitors with extremely high stability and reliability ideal for high temperature applications

With the wide range of existing capacitors, the end user's requirements are roughly met but most of the capacitors see their performances largely impacted when they are submitted to high temperature. In this paper we present the Silicon Capacitors highly recommended for applications in the geothermal, oil well logging, automotive and military. They can operate in a wide operating temperature range and they withstand temperature up to 250°C, with extremely high insulation resistance and very good stability. These capacitors, already extensively used for years in miniaturized equipment and computers, feature high miniaturization with a large capacitance to volume ratio, thanks to the IPDiA 3D Silicon technology, extremely stable and reliable even at 100μm thickness. Available in hundreds or thousands of nanofarads, in various sizes and custom configurations, these capacitors are usable at low frequencies but they are also appropriate for RF applications. The recent progress in the 3D Silicon Capacitor IPDIA technology, which moves the world wide record from 250nF/mm2 up to 550nF/mm2, will give even more room to higher integration. This is an ultra key driver to growth for High reliability applications.

BIPM direct on-site Josephson voltage standard comparisons: 20 years of results

The discovery of the Josephson effect has for the first time given national metrology institutes (NMIs) the possibility of maintaining voltage references which are stable in time. In addition, the introduction in 1990 of a conventional value for the Josephson constant, KJ-90, has greatly improved world-wide consistency among representations of the volt. For 20 years, the Bureau International des Poids et Mesures (BIPM) has conducted an ongoing, direct, on-site key comparison of Josephson voltage standards among NMIs under the denominations BIPM.EM-K10.a (1 V) and BIPM.EM-K10.b (10 V) in the framework of the mutual recognition arrangement (CIPM MRA). The results of 41 comparisons illustrate the consistency among primary voltage standards and have demonstrated that a relative total uncertainty of a few parts in 1010 is achievable if a few precautions are taken with regard to the measurement set-up. Of particular importance are the grounding, efficient filters and high insulation resistance of the measurement leads, and clean microwave distribution along the propagation line to the Josephson array. This paper reviews the comparison scheme and technical issues that need to be taken into account to achieve a relative uncertainty at the level of a few parts in 1010 or even a few parts in 1011 in the best cases.

Phase evolution of solid-state BaTiO3 powder prepared with the ultrafine BaCO3 and TiO2

Abstract

Dielectric Properties of (Ba,Ca)(Ti,Zr)O3 Based MLCC Novel Cofired with Ni by Free and Constrained Sintering

In this paper, the (Ba,Ca)(Ti,Zr)-MLCCs with nickel electrodes by free sintering and constrained sintering as different heating rate have been investigated as different heating rate with 200°C/hr, 1500°C/hr and 3000°C/hr, respectively. The BaTiO3 was adopted as constraining layer due to the tensile stress of generation resulted from the different onset temperature. The electrical characteristics were closely related to the microstructure change including electrode overlap areas and grain size by free and constrained sintering with different heating rate. The variation of dielectric constant and insulation resistance can be explained by grain size change. The variation of dielectric loss can be explained by the curve of the temperature coefficient of capacitance. To compare with the free sintering, the capacitance value of constrained sintering of MLCCs has increased regardless of the heating rates. The high capacitance, high electrode continuity (>98%) and high insulation resistance (>1010Ω) of BCTZ-based MLCC with nickel electrode can be attained by using a rapid constrained sintering technique.

Silicon Capacitors with extremely high stability and reliability ideal for high temperature applications

With the wide range of existing capacitors, the end user's requirements are roughly met but most of the capacitors see their performances largely impacted when they are submitted to high temperature. In this paper we present the Silicon Capacitors highly recommended for applications in the geothermal, oil well logging, automotive and military. They can operate in a wide operating temperature range and they withstand temperature up to 250°C, with extremely high insulation resistance and very good stability. These capacitors, already extensively used for years in miniaturized equipment and computers, feature high miniaturization with a large capacitance to volume ratio, thanks to the IPDiA 3D Silicon technology, extremely stable and reliable even at 100μm thickness. Available in hundreds or thousands of nanofarads, in various sizes and custom configurations, these capacitors are usable at low frequencies but they are also appropriate for RF applications. The recent progress in the 3D Silicon Capacitor IPDIA technology, which moves the world wide record from 250nF/mm2 up to 550nF/mm2, will give even more room to higher integration. This is an ultra key driver to growth for High reliability applications.

Study on Occupation Behavior of Y2O3 in X8R Nonreducible BaTiO3-Based Dielectric Ceramics

The effects of Y2O3 on BaTiO3–MgO–MnO2–CaZrO3 nonreducible ceramics were investigated. Specimens with Y2O3 contents ranging from 1.0 to 2.5 mol % were prepared via the solid state method. The Curie temperature (Tc) and the electrical properties were closely related to the occupation behavior of yttrium, which is known as an amphoteric element. Tc increased almost linearly as a function of Y2O3 content when the doping content was low. Transmission electron microscopy (TEM) indicated a typical “core–shell” structure. The lattice parameters corresponding to the grain cores and the shells were determined by X-ray diffractometry (XRD) separately. The relief of the internal stresses arising from the lattice mismatch was responsible for the Tc shift. The specimens doped by a high level of Y2O3 can fulfill the EIA X8R specification with a high dielectric constant (εRT > 2400) and a low dielectric loss (tan δ< 1.1%). A high insulation resistivity and a slow degradation rate were obtained when a sufficient amount of Y2O3 was incorporated, which were attributed to the substitution of Ti4+ and the formation of a donor–acceptor complex.

Effects of Sericite Modified by Macromolecular Dispersant on the Thermal, Mechanical and Electrical Properties of the NR/SBR Composites

A new hydrosoluble macromolecular dispersant and modifier, poly(ethylene glycol)-maleic anhydride-acrylic acid (PEG-MA-AA) terpolymer was synthesized via ring-opening reaction and free radical polymerization. The chemical structure of the PEG-MA-AA terpolymer was confirmed by Fourier transform infrared (FTIR) spectra and nuclear magnetic resonance spectroscopy (NMR), and its average molecular weight was determined by gel permeation chromatography (GPC). Modified sericite (MSE) was synthesized from sericite (SE) by the surface modification with PEG-MA-AA. The NR/SBR/MSE composites were prepared via the blending of the modified sericite and NR/SBR rubber. The thermal, mechanical and electrical properties of the composites were investigated by TGA, tensile test machine and high-insulation resistance meter. The results showed that the thermal stability and the mechanical and electrical insulation properties of NR/SBR/MSE composites were improved significantly. SEM also revealed that modified sericite possessed good dispersibility.

Preparation of Water-Based No-Clean Flux for High Temperature Lead-Free Solder

A series of water-based no-clean fluxes composed of an anion/nonion binary surfactant were investigated. The wetting behavior of Sn0.7Cu and Sn3.0Ag0.5Cu on copper with different content of binary surfactant, and the performance of the flux were tested according to the Chinese industry standard of SJ/T 11273-2002 (No-clean liquid Flux). The results showed that the wettability of binary complex was better than that of single surfactant. Two promising fluxes for Sn0.7Cu and Sn3.0Ag0.5Cu solder were selected, respectively. The fluxes showed excellent performance such as halogen-free, less corrosivity, low content of volatile organic compound (less than 5%), high spread rate (over 80%), and high surface insulation resistance (beyond 108Ω). The prepared fluxes meet the requirement of lead-free solder.

Preparation of BME MLCC Powders by Aqueous Chemical Coating Method

High and large capacitance base–metal–electrode multilayer ceramic capacitors (BME MLCCs) for future application require much thinner dielectric layers (&lt;l μm) than ever before, which means that grain size uniformity of BME MLCC powder should be effectively controlled. In this paper, high‐performance nanosized BME MLCC powder was developed by a novel and convenient aqueous chemical coating method. Various kinds of dispersants were used to disperse BaTiO3 particles in aqueous solutions. Poly(acrylic acid–comaleic acid) was found to be the best for dispersing. BaTiO3 particles were well coated by adding the doping elements into the uniform BaTiO3 slurry in the form of inorganic solutions and organic solutions under an appropriate pH value. Thermogravimetric analysis, transmission electron microscopy, and energy‐dispersive spectroscopy were utilized in the study of calcining, microstructures, and element analysis. The dielectric constants of the ceramics at room temperature could reach 2100, with low dielectric loss &lt;1.0% and high insulation resistivity ∼1012 Ω·cm. The average grain size is as low as about 130 nm.

Preparation of Epoxy Resin Thin Film by Electroless Deposition Method

The electrodeposition coating process, which is a polymer film deposition method using water electrolysis, is widely used for automobile body primers. Recently this process is being used in the insulating polymer films deposition for the microelectromechanical system (MEMS) or micro electric components. However, this process has difficulty in depositing polymer film on complex shapes and non-conductive surfaces. In this paper, we demonstrate that epoxy resin thin films used extensively as insulating polymer films were successfully deposited using the electroless chemical reaction in aqueous solution on a non-conductive surface and high aspect glass tube. The substrates catalyzed using a commercialized three-step Sn/Ag/Pd activation process were immersed in the reaction solution containing water-soluble resin and NO3- ion, reducing agent (DMAB). The pH near the substrate rose when NO3- was reduced by released electrons from DMAB. Water-soluble resin combined with OH-; hence, polymer thin film was deposited by the electroless deposition reaction. By FE-SEM and FT-IR measurement, it was clear that the conformal and dense epoxy resin films were deposited. Using the present method, epoxy films could be deposited on the surface of a high aspect ratio glass tube 50 mm in length and φ3 in inner diameter. These films had high insulation resistivity of 108∼1011Ωm with applied voltage of 250 V.

High-temperature stable dielectrics in Mn-modified (1-x) Bi0.5Na0.5TiO3-xCaTiO3 ceramics

In the current work, the bulk (1-x) Bi0.5Na0.5TiO3-xCaTiO3 [BNCT100x] system was synthesized via solid-state route. CaTiO3 in solid solution with Bi0.5Na0.5TiO3 was observed to decrease the dielectric constant at higher temperature and raise the dielectric constant at lower temperature. Polarization hysteresis measurements indicated that the ferroelectricity of Bi0.5Na0.5TiO3 was weakened with an increase of CaTiO3, resulted in the shift of the depolarization temperature (T d) toward lower temperatures. X-ray diffraction analysis revealed that TiO2 was produced as a secondary phase due to the losses of Bi and Na during milling and sintering processes. Moreover, the addition of Ca promoted the segregation of Ti out of BNT grains. Dielectric properties of BNCT12 ceramics with different dopant levels of Mn were characterized as a function of temperature for potential use of high-temperature capacitors. Modification of BNCT12 materials with Mn improved the temperature characteristic of capacitance (−55°C to 250°C, △C/C25°C ≤ ±15%). Finally, by doping 1.5 wt% Mn, the dielectric constant at room temperature could reach over 900, with a low dielectric loss below 1% and a high insulation resistivity about 1012 Ω•cm. Furthermore, a small amount of Mn influenced the microstructure in the way to inhibit the long grains and grain growth of BNCT solution ceramics. However, excess Mn caused abnormal grain growth, and therefore, rectangle grains appeared again.

Studies on the Morphological, Rheological, Electrical, Mechanical and Thermal Properties of the PTT/SCF Composites

Short carbon fiber reinforced poly(trimethylene terephthalate) composites (PTT/SCF) were investigated in their rheology behaviors, phase morphology, electrical, mechanical, and thermal properties by capillary rheometer, scanning electron microscope, universal tester, high insulation resistance meter, Q meter, and thermal gravimetric analyzer. PTT/SCF melt is the dilating fluid at a shear rate below 130 s-1, while it becomes pseudo-plastic fluid at a shear rate higher than 130 s- 1. Melt apparent viscosity and viscous flow activation energy increase initially, and then decrease as SCF content increases, which have maximum values with 2 wt% SCF. The interaction between SCF and PTT matrix is strong based on the observation from the fracture surface of composites. The tensile strength and rupture strength are all increased obviously with increasing SCF; while the impact strength reaches a maximum value as SCF contents is 5%. With increasing SCF content in matrix, the electrical resistivity is decreased, while the dielectric constant, and the dielectric loss tangent were increased.

Effects of Ca and Zr additions and stoichiometry on the electrical properties of barium titanate-based ceramics

(Ba1−xCax)m(Ti1−yZry)O3 (BCTZ-x-y-m) ceramics were studied to clarify the effects of Ca and/or Zr addition and the non-stoichiometry of BCTZ ceramics. The range of each element was 0.00 ≦ x, y ≦ 0.25 and 0.995 ≦ m ≦ 1.02. All powders were prepared by a solid state reaction method. Green bodies with disc shapes were sintered at 1500°C for 2 h in air and then reheated at 950°C for 5 h in various reducing conditions. The dielectrics with the substitution of Ca ion in BCTZ-x-0.0-1.01 (x ≦ 0.10) showed an increase in Tc and the insulation resistivity improved with increasing x. The increase of Zr content (y) in BCTZ-0.1-y-1.01 and m in BCTZ-0.1-0.1-m led to the phase transition of dielectrics to relaxors, accompanying the decrease of Tc. In BCTZ-0.1-0.1-m, Ca and Zr co-doped dielectrics showed a high insulation resistivity (IR), even though m = 1.00. There are two possible origins of the higher resistivity observed in BCTZ with m = 1.0. The first is the acceptor action of Ca ions that moved from Ba sites to Ti sites in BaTiO3; the second is the higher charge stability of the Zr ion than that of the Ti ion in a reducing atmosphere.

Formation of Core‐Shell Structure in Ultrafine‐Grained BaTiO3‐Based Ceramics Through Nanodopant Method

The formation of core‐shell structure is the key issue of temperature stable barium titanate‐based dielectric ceramic for multilayer ceramic capacitor application. It is difficult to obtain and observe the core‐shell structure in ceramic grains when the grain size becomes smaller, especially to sizes &lt;200 nm. A nanodopant method has been developed for the preparation of ultrafine‐grained barium titanate‐based ceramics with grain size below 200 nm. The existence of core‐shell structure was proved by transmission electron microscopy observation and energy‐dispersive spectroscopy analysis. High‐performance X7R dielectric ceramics were produced in a reducing atmosphere by normal sintering and two‐step sintering method. The dielectric constant at room temperature could reach over 2000, with a low dielectric loss at about 1.0% and high insulation resistivity ∼1012Ω·cm.

Dielectric Properties of Polymer-ceramic Composites for Embedded Capacitors

Ceramic-polymer composites have been investigated for their suitability as embedded capacitor materials because they combine the processing ability of polymers with the desired dielectric properties of ceramics. This paper discusses the dielectric properties of the ceramic (<TEX>$BaTiO_3$</TEX>)-polymer (Epoxy) composition as a function of ceramic particle size at a ceramic loading of 40 vol%. The dielectric constant of these ceramic-polymer composites increases as the powder size decreases. Results show that ceramic-polymer composites have a high dielectric constant associated with the <TEX>$BaTiO_3$</TEX> powder with a 200 nm particle size, high insulation resistance, high breakdown voltage (> 22 KV/mm), and low dielectric loss (0.018-0.024) at 1 MHz.

Preparation of ZnNb 2O 6–TiO 2 microwave dielectric ceramics for multi-layer cofired component

In this paper, the microwave dielectric behavior of ZnNb 2O 6–TiO 2 ceramics synthesized at different conditions was studied. ZnNb 2O 6–1.75TiO 2 ceramics, sintered at 1050 °C, exhibited a good dielectric behavior. CuO and B 2O 3 were used as sintering aids to decrease the sintering temperature of the above materials. According to XRD analysis, the reaction between columbite ZnNb 2O 6 and rutile occurred, resulted in new phase ZnTiNb 2O 8 and Zn 0.17Nb 0.33Ti 0.5O 2. The change of crystal grain and densification was also observed with SEM. Results indicated that the dielectric behavior of samples strongly depended on structural transitions and microstructure of materials. We found that 2.0 wt.% CuO doped ZnNb 2O 6–1.75TiO 2 ceramics with 2.0 wt.% B 2O 3 additive sintered at 975 °C exhibited good dielectric properties: ɛ r = 40, Q × f = 17,000 GHz (at 5.6 GHz) and τ f = −12 ppm °C −1. The high specific insulation resistance and excellent compatibility with Ag 90Pd 10 electrode suggested that ZnNb 2O 6–1.75TiO 2 ceramics was suitable for manufacturing multilayer ceramic capacitors with a high reliability.

임베디드 커패시터용 세라믹(BaTiO3)-고분자(에폭시) 필름의 세라믹 분말 형상 및 함량에 따른 전기적 특성

The ceramic()-polymer(epoxy) composites have been widely investigated as dielectric materials for embedded capacitors in printed circuit boards (PCBs). The dielectric properties of /epoxy composites prepared using the agglomerated particles were investigated in the present study. The dielectric constants of the composites prepared using the agglomerated particles were about 2 times higher than those of the composites with the dispersed particles. The insulation resistance of the composites prepared using the agglomerated particles were lower than those of the composites with dispersed particles. As a result, there is tradeoff between high dielectric constant and insulation resistance in the /epoxy composites. So it is important to select proper agglomerated or dispersed particles in accordance with needs.