Development of High Permeability Core Materials for Embeddable Inductors in Flexible Organic Substrates

AbstractCapacitors, resistors and inductors are surface mounted components on circuit boards, which occupy up to 70% of the circuit board area. For selected applications, these passives are packaged inside green ceramic tape substrates and sintered at temperatures over 700°C in a co-fired process. These high temperature processes are incompatible with organic substrates, and low temperature processes are needed if passives are to be embedded into organic substrates. A new high permeability dual-phase Nickel Zinc Ferrite (DP NZF) core fabricated using a low temperature sol-gel route was developed for use in embedded inductors in organic substrates. Crystalline NZF powder was added to the sol-gel precursor of NZF. The solution was deposited onto the substrates as thin films and heat-treated at different temperatures. The changes in the microstructures were characterized using XRD and SEM. Results showed that addition of NZF powder induced low temperature transformation of the sol-gel NZF phase to high permeability phase at 250°C, which is approximately 350°C lower than transformation temperature for pure NZF sol gel films. Electrical measurements of DP NZF cored two-layered spiral inductors indicated that the inductance increased by three times compared to inductors without the DP NZF cores. From microstructural observations, the increase is correlated with the changes in microstructural connectivity of the powder phase.

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Natural Convection and Passive Heat Rejection from Two Heat Sources Maintained at Different Temperatures on a Printed Circuit Board

Journal of Electronic Packaging ◽

10.1115/1.1635393 ◽

2004 ◽

Vol 126 (1) ◽

pp. 14-21 ◽

Cited By ~ 3

Author(s):

Randy D. Weinstein ◽

Amy S. Fleischer ◽

Kimberly A. Krug

Keyword(s):

Natural Convection ◽

Power Dissipation ◽

Printed Circuit Board ◽

Circuit Board ◽

Heat Sources ◽

Circuit Boards ◽

Vertical Orientation ◽

Heat Rejection ◽

Different Temperatures ◽

Independent Heat

Natural convection and passive heat rejection from two independent heat sources maintained at different temperatures (60°C and 100°C above ambient) on single circuit boards (FR4 and copper clad FR4) are experimentally studied. The effect of heat source location on maximum power dissipation is presented for both horizontal and vertical orientations. Heat losses due to radiation, natural convection and board conduction are quantified. As long as the heat sources are more than 2 cm apart, they do not influence each other on the FR4 board. Vertical orientation increases the power dissipation in the components by up to 30% for the FR4 board and 15% for the copper clad board. Two ounces of copper cladding increases the overall power dissipation by 150–190%.

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CBED study of low-temperature InP grown by gas source MBE

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010014988x ◽

1993 ◽

Vol 51 ◽

pp. 810-811

Author(s):

R. Rajesh ◽

M.J. Kim ◽

J.S. Bow ◽

R.W. Carpenter ◽

G.N. Maracas

Keyword(s):

Low Temperature ◽

Second Phase ◽

Material System ◽

Ion Milling ◽

Electrical Measurements ◽

Gas Source ◽

Structural And Electrical Properties ◽

The One ◽

Lt Inp ◽

Gas Source Mbe

In our previous work on MBE grown low temperature (LT) InP, attempts had been made to understand the relationships between the structural and electrical properties of this material system. Electrical measurements had established an enhancement of the resistivity of the phosphorus-rich LT InP layers with annealing under a P2 flux, which was directly correlated with the presence of second-phase particles. Further investigations, however, have revealed the presence of two fundamentally different types of precipitates. The first type are the surface particles, essentially an artefact of argon ion milling and containing mostly pure indium. The second type and the one more important to the study are the dense precipitates in the bulk of the annealed layers. These are phosphorus-rich and are believed to contribute to the improvement in the resistivity of the material.The observation of metallic indium islands solely in the annealed LT layers warranted further study in order to better understand the exact reasons for their formation.

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Effect of MCl (M = Na, K) addition on microstructure and electrical conductivity of forsterite

The European Physical Journal Applied Physics ◽

10.1051/epjap/2020200161 ◽

2020 ◽

Vol 92 (1) ◽

pp. 10901

Author(s):

Saloua El Asri ◽

Hamid Ahamdane ◽

Lahoucine Hajji ◽

Mohamed El Hadri ◽

Moulay Ahmed El Idrissi Raghni ◽

...

Keyword(s):

Heat Treatment ◽

Electrical Conductivity ◽

Single Phase ◽

Sol Gel ◽

Complex Impedance ◽

Transmission Spectra ◽

Electrical Measurements ◽

Cation Type ◽

Edx Analyses ◽

The Fourier Transform

Forsterite single phase powder Mg2SiO4 was synthesized by sol–gel method alongside with heat treatment, using two different cation alkaline salts MCl as mineralizers (M = Na, K) with various mass percentages (2.5, 5, 7.5, and 10 wt.%). In this work, we report on the effect of the cation type and the added amount of used mineralizer on microstructure and electrical conductivity of Mg2SiO4. The formation of forsterite started at 680–740 °C and at 630–700 °C with KCl and NaCl respectively, as shown by TG-DTA and confirmed by XRD. Furthermore, the Fourier transform infrared (FTIR) transmission spectra indicated bands corresponding to vibrations of forsterite structure. The morphology and elemental composition of sintered ceramics were examined by SEM-EDX analyses, while their densities, which were measured by Archimedes method, increased with addition of both alkaline salts. The electrical measurements were performed by Complex Impedance Spectroscopy. The results showed that electrical conductivity increased with the addition of both mineralizers, which was higher for samples prepared with NaCl than those prepared with KCl.

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Degradation Analysis of Thick Film Chip Resistors

ISTFA 2009: Conference Proceedings from the 35th International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2009p0293 ◽

2009 ◽

Author(s):

Bhanu Sood ◽

Diganta Das ◽

Michael H. Azarian ◽

Michael Pecht

Keyword(s):

Thick Film ◽

Printed Circuit Board ◽

Negative Resistance ◽

Circuit Board ◽

High Humidity ◽

Circuit Boards ◽

Chemical Modifications ◽

Current Leakage ◽

Printed Circuit ◽

Degradation Analysis

Abstract Negative resistance drift in thick film chip resistors in high temperature and high humidity application conditions was investigated. This paper reports on the investigation of possible causes including formation of current leakage paths on the printed circuit board, delamination between the resistor protective coating and laser trim, and the possibility of silver migration or copper dendrite formation. Analysis was performed on a set of circuit boards exhibiting failures due to this phenomenon. Electrical tests after mechanical and chemical modifications showed that the drift was most likely caused by moisture ingress that created a conductive path across the laser trim.

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Dielectric Breakdown in Printed Circuit Boards at Elevated Temperatures

ISTFA 1996: Conference Proceedings from the 22nd International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa1996p0357 ◽

1996 ◽

Author(s):

P. Singh ◽

G.T. Galyon ◽

J. Obrzut ◽

W.A. Alpaugh

Keyword(s):

Experimental Data ◽

Thermal Degradation ◽

Printed Circuit Boards ◽

Printed Circuit Board ◽

Elevated Temperatures ◽

Dielectric Breakdown ◽

Circuit Board ◽

Circuit Boards ◽

Printed Circuit ◽

Data Matching

Abstract A time delayed dielectric breakdown in printed circuit boards, operating at temperatures below the epoxy resin insulation thermo-electrical limits, is reported. The safe temperature-voltage operating regime was estimated and related to the glass-rubber transition (To) of printed circuit board dielectric. The TG was measured using DSC and compared with that determined from electrical conductivity of the laminate in the glassy and rubbery state. A failure model was developed and fitted to the experimental data matching a localized thermal degradation of the dielectric and time dependency. The model is based on localized heating of an insulation resistance defect that under certain voltage bias can exceed the TG, thus, initiating thermal degradation of the resin. The model agrees well with the experimental data and indicates that the failure rate and truncation time beyond which the probability of failure becomes insignificant, decreases with increasing glass-rubber transition temperature.

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GERMINATION AND VIGOUR IN SEEDS OF THE COWPEA IN RESPONSE TO SALT AND HEAT STRESS

Revista Caatinga ◽

10.1590/1983-21252019v32n115rc ◽

2019 ◽

Vol 32 (1) ◽

pp. 143-151 ◽

Cited By ~ 1

Author(s):

Luma Rayane de Lima Nunes ◽

Paloma Rayane Pinheiro ◽

Charles Lobo Pinheiro ◽

Kelly Andressa Peres Lima ◽

Alek Sandro Dutra

Keyword(s):

Salt Stress ◽

Heat Stress ◽

High Temperature ◽

Low Temperature ◽

Vigna Unguiculata ◽

Salt Concentration ◽

Dry Weight ◽

Germination Percentage ◽

Different Types ◽

Different Temperatures

ABSTRACT Salinity is prejudicial to plant development, causing different types of damage to species, or even between genotypes of the same species, with the effects being aggravated when combined with other types of stress, such as heat stress. The aim of this study was to evaluate the tolerance of cowpea genotypes (Vigna unguiculata L. Walp.) to salt stress at different temperatures. Seeds of the Pujante, Epace 10 and Marataoã genotypes were placed on paper rolls (Germitest®) moistened with different salt concentrations of 0.0 (control), 1.5, 3.0, 4.5 and 6.0 dS m-1, and placed in a germination chamber (BOD) at temperatures of 20, 25, 30 and 35°C. The experiment was conducted in a completely randomised design, in a 3 × 4 × 5 scheme of subdivided plots, with four replications per treatment. The variables under analysis were germination percentage, first germination count, shoot and root length, and total seedling dry weight. At temperatures of 30 and 35°C, increases in the salt concentration were more damaging to germination in the Epace 10 and Pujante genotypes, while for the Marataoã genotype, damage occurred at the temperature of 20°C. At 25°C, germination and vigour in the genotypes were higher, with the Pujante genotype proving to be more tolerant to salt stress, whereas Epace 10 and Marataoã were more tolerant to high temperatures. Germination in the cowpea genotypes was more sensitive to salt stress when subjected to heat stress caused by the low temperature of 20°C or high temperature of 35°C.

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Reversal of triboelectric charges on sol–gel oxide films annealed at different temperatures

Applied Physics Letters ◽

10.1063/5.0055312 ◽

2021 ◽

Vol 118 (24) ◽

pp. 243902

Author(s):

Yongqiao Zhu ◽

Shiquan Lin ◽

Wenchao Gao ◽

Miao Zhang ◽

Dawei Li ◽

...

Keyword(s):

Sol Gel ◽

Oxide Films ◽

Different Temperatures

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Elucidation of the Crystal Growth Characteristics of SnO2 Nanoaggregates Formed by Sequential Low-Temperature Sol-Gel Reaction and Freeze Drying

Nanomaterials ◽

10.3390/nano11071738 ◽

2021 ◽

Vol 11 (7) ◽

pp. 1738

Author(s):

Saeid Vafaei ◽

Alexander Wolosz ◽

Catlin Ethridge ◽

Udo Schnupf ◽

Nagisa Hattori ◽

...

Keyword(s):

Crystal Growth ◽

Low Temperature ◽

Photoelectron Spectroscopy ◽

High Performance ◽

Freeze Drying ◽

Sno2 Nanoparticles ◽

Sol Gel ◽

Functional Materials ◽

Cost Effective ◽

High Concentration

SnO2 nanoparticles are regarded as attractive, functional materials because of their versatile applications. SnO2 nanoaggregates with single-nanometer-scale lumpy surfaces provide opportunities to enhance hetero-material interfacial areas, leading to the performance improvement of materials and devices. For the first time, we demonstrate that SnO2 nanoaggregates with oxygen vacancies can be produced by a simple, low-temperature sol-gel approach combined with freeze-drying. We characterize the initiation of the low-temperature crystal growth of the obtained SnO2 nanoaggregates using high-resolution transmission electron microscopy (HRTEM). The results indicate that Sn (II) hydroxide precursors are converted into submicrometer-scale nanoaggregates consisting of uniform SnO2 spherical nanocrystals (2~5 nm in size). As the sol-gel reaction time increases, further crystallization is observed through the neighboring particles in a confined part of the aggregates, while the specific surface areas of the SnO2 samples increase concomitantly. In addition, X-ray photoelectron spectroscopy (XPS) measurements suggest that Sn (II) ions exist in the SnO2 samples when the reactions are stopped after a short time or when a relatively high concentration of Sn (II) is involved in the corresponding sol-gel reactions. Understanding this low-temperature growth of 3D SnO2 will provide new avenues for developing and producing high-performance, photofunctional nanomaterials via a cost-effective and scalable method.

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