Recent developments in the pressure wave propagation method

HoIe, S.

doi:10.1109/mei.2009.4976898

Cited by 25 publications

(12 citation statements)

References 39 publications

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“…Research on space charge behavior using nondestructive methods was first proposed by Collins, [ 44 ] and a number of measurement methods were developed afterward, [ 45–49 ] among which the pulsed electroacoustic (PEA) method [ 50 ] became one of the most commonly used space charge measuring methods till now. Thanks to these methods, encouraging progress has been made in understanding the space charge behavior in the past decades.…”

Section: Introductionmentioning

confidence: 99%

Space Charge Behavior in Epoxy‐Based Dielectrics: Progress and Perspective

Liu

Xie

et al. 2022

Adv Elect Materials

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temperature and complex electric field conditions. [1][2][3] Epoxy resin (EP) is a class of polymer oligomers containing two or more epoxide groups based on organic compounds (e.g., aliphatic, alicyclic, and aromatic). As a prepolymer, EP shows excellent performance after its reaction with a curing agent to form an insoluble polymer with a 3D network structure. EP has desirable insulating characteristics, [4][5][6][7] heat resistance, [8] high mechanical strength, [9] low shrinkage, [10] chemical stability, and adhesive properties, which originate from its compact structure and tunable functional groups. The above mentioned outstanding performances, along with characteristics of easy processing and formula design flexibility, enable the extensive use of EP-based materials in power equipment and electronic devices [11] (Figure 1), including bar insulation and impregnating varnish in transformers, main insulation in dry-type bushings and wall bushings, insulator in gas-insulated switchgear (GIS) and gas-insulated transmission line (GIL), epoxy molding compound for integrated circuit (IC) packaging. It is noteworthy that EPs typically possess lower glass transition temperature (T g ) compared to other high-T g dielectric polymer substitutes used in microelectronic systems such as benzocyclobutene, [12] polyimide (PI), [13] and maleimide. [14] Besides high T g , high thermal conductivity and low coefficient of thermal expansion of EPs are always desired for their industrial applications, especially from an electronic packaging perspective. To date, considerable efforts have been made to improve the heat endurance and heat dissipation capabilities of EP-based dielectric materials by inorganic particle doping [15][16][17][18][19][20][21][22][23][24] and chemical modification. [25][26][27] Furthermore, EP is also an indispensable adhesive that is extensively used in power equipment. [28][29][30][31][32] Yet, potential reliability hazards may exist during the operation of power equipment and electronic devices, especially at high temperatures and under high voltage direct current (HVDC) application, one of which is the space charge accumulation in EP-based dielectric materials. [29,30,33,34] The accumulated space charge may cause deterioration/aging and even partial discharge or dielectric breakdown of dielectric materials. [35][36][37][38][39][40] Specifically, the extensive application of EP-based dielectric materials in HVDC transmission projects eagerly calls for relevant studies on the space charge behavior Epoxy-based dielectrics are extensively used in grid-connected energy systems and modern microelectronics as electrical insulation, adhesive, and packaging components. However, space charge accumulation in epoxy-based dielectrics is a foremost factor threatening device stability and lifespan, especially under conditions of high voltage direct current and high temperatures during long-term operation, and thus are investigated systematically. This article reviews the state-of-the-art progress in understanding and r...

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Section: Introductionmentioning

confidence: 99%

Space Charge Behavior in Epoxy‐Based Dielectrics: Progress and Perspective

Liu

Xie

et al. 2022

Adv Elect Materials

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“…Its resolution can reach 100 nm when using the femtosecond laser. However, due to the limitation of the target electrode generating pressure wave excitations, the resolution is difficult to further improve [18]. The resolutions of thermal methods are not illustrated here due to its slow measurement process and thermal excitation attenuation.…”

Section: Key Evaluation Indicators Of Space Chargementioning

confidence: 99%

“…When a force is applied to the sensor, the phase difference ϕ of the two components can be approximately characterized by (11). The light intensities of the two emitted lights from the Wollaston prism can then be expressed by (18).…”

Section: B Transformation and Detection Of Polarized Light In Ellipsometry Detection Systemmentioning

confidence: 99%

“…In contrast, based on the laser induced pressure pulse method, the spatial resolution can reach 100 nm when using the femtosecond laser. However, it is difficult to further improve due to the limitation of target electrode [18]. The research in [19] also shows that the femtosecond laser can cause nanometer-scale displacements of sample surface.…”

Section: Introductionmentioning

confidence: 99%

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Explorative Study on a Novel Ellipsometry Detection Method for Space Charge Inside Solid Insulation: Towards High Temporal and Spatial Resolutions

Ren

Gao

et al. 2021

IEEE Sensors J.

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The resolution performance of space charge measurement method determines its application environment and measured information, which has put forward higher temporal and spatial resolution requirements for the charge evaluation of electronic equipment insulation. Based on the ellipsometry detection principle and the photoelastic effect of the sensor, a novel optical method for space charge measurement is proposed. The potentials of the method in terms of single measurement with high signal-to-noise ratio, terahertz bandwidth and nanometer spatial resolution are analyzed. By deriving the mathematical relationship of the signal transmission, it is indicated that the light intensity difference measured by the system can linearly present the elastic force generated from space charge. Based on the built ellipsometry detection system, it is found that the detected signal from the sensor can quickly track the imposed elastic waves with different amplitudes and frequencies, which verifies the feasibility of the crucial detection part and the fast measurement speed of the proposed method. Further simulation results indicate that the refractivity performance of the sensor under the effect of elastic waves can present the deformation variation with a spatial resolution of 2 nm. Therefore, the given explorative research can provide the key theoretical basis and experimental verification for the proposed method.

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“…However, an overarching interpretation of these physical phenomenon calls for the use of an additional characterization method for calculating the material charge profile. Various apparatus such as thermal [9], pressure wave [10] and pulsed electro-acoustic (PEA) system [11] have been developed for these purposes over the past 15 years. Some of the above methods were used to estimate in open air the electric charge inside insulators after irradiation, which means that the specimen should be detached from the irradiation facility [12].…”

Section: Introductionmentioning

confidence: 99%